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SNOMED CT® User Guide - Information Standards Board for Health

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1. PROCEDURE CONTEXT Planned qualifier value Context values for actions 288532009 lt lt Q 4 9 9 TEMPORAL CONTEXT This attribute indicates the time of occurrence of the situation indicating whether the procedure or finding that it represents is actual and therefore occurred in the present in the past or at a specified time or that it is planned or expected that is temporally located in the future The most general value is simply Current or past actual meaning that the concept was actual not planned or expected but not specifying anything further about its time The word specified in the TEMPORAL CONTEXT values means that there is a date time stamp associated with the code in the record that gives a date and or time as a point and or interval that applies to the concept Table 68 Permissible values for TEMPORAL CONTEXT Attribute Values Temporal context value 410510008 lt lt Q ister af remerunia siiatani e ASSOCIATED FINDING Blood in urine finding TEMPORAL CONTEXT In the past qualifier value O 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 59 4 9 10 SUBJECT RELATIONSHIP CONTEXT This attribute is used to specify the subject of the Clinical finding or Procedure being recorded in relation to the subject of the record In the example below the subject of the record is the patient
2. 2002 2011 The International Health Terminology Standards Development Organisation 18 SNOMED CT User Guide January 2011 3 1 Concepts In the context of this document a concept is a clinical meaning identified by a unique numeric identifier Conceptld that never changes Concepts are represented by a unique human readable Fully Specified Name FSN The concepts are formally defined in terms of their relationships with other concepts These logical definitions give explicit meaning which a computer can process and query on Every concept also has a set of terms that name the concept in a human readable way 3 1 1 Concept granularity The meaning represented by a Concept can be general for example procedure specific for example excisional biopsy of lymph node or somewhere in between for example biopsy of lymph node e More specific Concepts Have finer granularity more granular e Represent clinical detail e More general Concepts e Have coarser granularity less granular e Represent less clinical detail e Aggregate similar Concepts Support for multiple levels of granularity allows SNOMED CT to be used to represent clinical data at a level of detail that is appropriate to a range of different uses Concepts with different levels of granularity are linked to one another by is a relationships This enables appropriate aggregation of specific information within less detailed categories O 2002
3. 9 29 Modeler A person who directly edits the logic definitions and other structures of the terminology Also sometimes called Clinical Editor or Terminology Manager SNOMED CT modeler Modeller SNOMED CT author 9 30 Modeling The process of editing logic definitions to reflect the meaning intended by the fully specified name SNOMED CT modeling Modelling SNOMED CT authoring 9 31 Namespaceld A Namespace is a virtual block of identifiers allocated for creating Extensions to SNOMED CT The Namespace Identifier is a seven digit number that identifies the Namespace and is used as part of each Extension SCTID When an organization creates an extension to SNOMED CT the new components in the extension need to be identified as part of that particular organization extension IHTSDO allocates a Namespace Identifier to the organization which then uses it to form its Extension SCTIDs Most SCTID s issued by IHTSDO for the International Release are from the core namespace as determined by the partition identifier portion of the SCT D and do not use a Namespace identifier 2002 2011 The International Health Terminology Standards Development Organisation 100 SNOMED CT User Guide January 2011 Namespace id Namespace identifier Namespace 9 32 Partitionld A pair of digits that indicate whether an SCTID identifies a Concept Description Relationship Subset History or Extension component The partition identifier consists of the
4. S 4 5 5 SCALE TYPE This attribute refers to the scale of the result of an observation of a diagnostic test i e quantitative qualitative semi quantitative Table 50 Permissible values for SCALE TYPE Quantitative 30766002 lt lt Qualitative 26716007 lt lt Ordinal value 117363000 lt lt Ordinal or quantitative value 117365007 lt lt Nominal value 117362005 lt lt Narrative value 117364006 lt lt Text value 117444000 lt lt 4 5 6 MEASUREMENT METHOD This attribute specifies the method by which a procedure is performed 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 51 Table 51 Permissible values for MEASUREMENT METHOD Laboratory procedure categorized by method 127789004 lt For measurement procedures the attribute METHOD is given the value Measurement action qualifier value The attribute MEASUREMENT METHOD can be used to provide additional specificity S 4 6 Attributes used to define Specimen concepts Table 52 Approved Specimen attributes summary Defining Attribute Allowable Values SPECIMEN PROCEDURE Procedure 71388002 lt SPECIMEN SOURCE TOPOGRAPHY Anatomical or acquired body structure 442083009 SPECIMEN SOURCE MORPHOLOGY Morphologically abnormal structure 49755003 lt lt SPECIMEN SUBSTANCE Substance 105590001 lt lt SPECIMEN S
5. TEMPORAL CONTEXT 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 57 4 9 5 ASSOCIATED FINDING This attribute links concepts in the Situation with explicit context hierarchy to their related Clinical finding It specifies the Clinical finding concept whose context is being modified Table 64 Permissible values for ASSOCIATED FINDING Attribute Values Clinical finding 404684003 lt lt Q Family history of stroke situation Event 272379006 lt lt Q ASSOCIATED FINDING Cerebrovascular accident disorder Observable entity 363787002 lt Q only Link assertion 416698001 lt Q only Procedure 71388002 lt Q only a Note When ASSOCIATED FINDING is used in post coordinated expressions its range is broader than when used in distributed content ASSOCIATED FINDING must not reference concepts that already have pre coordinated context themselves For example the following definition uses FH Thyroid disorder incorrectly History of thyroid disease in father SUBJECT RELATIONSHIP CONTEXT father ASSOCIATED FINDING FH Thyroid disorder The following is the correct definition History of thyroid disease in father SUBJECT RELATIONSHIP CONTEXT father ASSOCIATED FINDING thyroid disease S 4 9 6 FINDING CONTEXT The FINDING CONTEXT attribute is used to repre
6. Top level concept code Top level metadata code O 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 93 9 1 Attribute An attribute represents a characteristic of the meaning of a concept or the nature of a refinement ug Note An attribute has a name which is represented by a concept All the concepts that can be used to name attributes are subtypes of the concept concept model attribute An attribute is assigned a value attribute value pair when used in the definition of a concept or in a post coordinated expression The permitted attribute values range for an attribute depend on the attribute name and on the domain of the concept being refined ug Example Finding site Concept Model Attribute Relationship Type Role 9 2 Attribute value pair An attribute value pair is made up of an attribute name and an attribute value Attribute value pairs allow additional types of information to be represented in a generic way without altering the underlying structure or information model SNOMED CT relationships are use attribute value pairs to represent relationships using one concept identifier as an attribute name the relationship type and another concept identifier as the value Similarly each refinement in a post coordinated expression consists of an attribute name and a value each of which is expressed as a concept identifier 9 3 Browser A computer application or
7. E ln E E INTERNATIONAL HEALTH TERMINOLOGY a STANDARDS DEVELOPMENT ORGANISATION H p at E 2 E SNOMED CT User Guide January 2011 International Release US English 2002 2011 International Health Terminology Standards Development Organisation CVR 30363434 2 SNOMED CT User Guide January 2011 Contents Chapter 1 Preface 2 2 2 c2c2c cccececnceccecececennnennceencescesdcasaverectchirttercnenese 7 PUSO dd ere 8 Who should read this guide eee ti 8 Notation Used in this COCUMENL eeeeeceeee scene eee ee eaaeeeeeeeaaeeeeeeeaaaeeeeeeeaaeeeeeeeeaaeeeeeeenaaeeeenenaees 8 SAUS it A ieee aad eel 8 Additional inforMatiON oococnnnnonccinnnnoccccnnnnancnccnnn nn nn cn nn c cnn naar cnn rre 9 IHTSDO Contact Detalls sissano ii a ian nn 10 Inventory Of DOCUMENTATION sics iatea re ee a a e a et ee 10 Additional DoCUMENtATION ssie ranae arii terena tra Na ARRET AAi AASEN AE PAEA PINATA 10 Document HISTO aa nite tn 11 Copyright NOTO eaea ana Se ee ee ee eas te tee 13 Chapter 2 Overview as 15 What is SNOMED CI Russia ia 16 SNOMED CT USES dd e ed la ee 16 Chapter 3 Basic Components of SNOMED CTennoncnccccccccnnccnninnaananoos 17 Concepts tinca tial fae te niall ied 18 Concept granular Maes ate ein GA ee rh ee eds Ate 18 Concept identifierS onooocnnnnnnnnnidcnnnnnnnnccnnoccconnccnnnn nn cnn nnrn nana cnn rca cnn nc arca 19 DESCIPTIONS iii ree aati NAE EN see EA Sayeed dh eee eee eaae den denon NA 20 Types Of C
8. FINDING METHOD Procedure 71388002 lt FINDING INFORMER Performer of method 420158005 lt lt Subject of record or other provider of history 419358007 lt lt oe Note Meaning of Allowable Values Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship 4 3 1 FINDING SITE This attribute specifies the body site affected by a condition Table 5 Permissible values for FINDING SITE Attribute Values Anatomical or acquired body structure 442083009 Kidney disease disorder lt lt FINDING SITE Kidney structure body structure Appendicitis disorder FINDING SITE Appendix structure body structure 4 3 2 ASSOCIATED MORPHOLOGY This attribute specifies the morphologic changes seen at the tissue or cellular level that are characteristic features of a disease 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 31 Table 6 Permissible values for ASSOCIATED MORPHOLOGY Attribute Values Bone marrow hyperplasia disorder ASSOCIATED MORPHOLOGY Hyperplasia morphologic abnormality Morphologically abnormal structure 49755003 lt lt Pancreatiti
9. The AMP represents the single unit dose of a medicinal product that is or has been made or marketed by a specific manufacturer trademarked brand name pharmaceutical products Its description requires product name strength dosage form flavor where applicable and manufacturer but it does not include explicit information about packaging 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 69 Because AMP concepts contain brand and country specific information they are not represented within the International Release of SNOMED CT but may instead exist within an identified domain extension contact your IHTSDO National Release Center Center for further information Actual Medicinal Products in an extension have a direct link to their virtual equivalent in the International Release via the is a relationship Example Sertraline 50mg tablet VMP found in the product International Release Zoloft 50mg tablet product AMP found in the extension All concepts in the Pharmaceutical biologic product hierarchy have a FSN tag of product regardless of their level of granularity 2002 2011 The International Health Terminology Standards Development Organisation 70 SNOMED CT User Guide January 2011 SNOMED CT concept Pharmaceutical Biologic Substance product ISA ISA Multiple Layers Multiple Layers Product Category drug product class Thrombolyt
10. hierarchy contains the sub hierarchy of Disease Concepts that are descendants of Disease or disorders are always and necessarily abnormal clinical states Multi axial subtype hierarchies allow diseases to be subtypes of other disorders as well as subtypes of findings Examples of Disease concepts Tuberculosis disorder non Hodgkin s lymphoma disorder 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 65 5 3 Procedure Procedure concepts represent activities performed in the provision of health care This hierarchy represents a broad variety of activities including but not limited to invasive procedures e g Excision of intracranial artery procedure administration of medicines e g Pertussis vaccination procedure imaging procedures e g Ultrasonography of breast procedure education procedures e g Low salt diet education procedure and administrative procedures e g Medical records transfer procedure Examples of Procedure concepts Removal of urethral catheter procedure Intravenous steroid injection procedure Irrigation of oral wound procedure e Appendectomy procedure 5 4 Situation with explicit context Concepts in the Procedure and Clinical finding hierarchies given the appropriate record structure can be used in a clinical record to represent e Conditio
11. which is the key of the Concepts Table in this case it is less ambiguous to use the term conceptld or concept code The real world referent s of the Conceptla that is the class of entities in reality which the Conceptldrepresents in this case it is less ambiguous to use the term meaning or code meaning SNOMED CT concept 9 7 Concept equivalence Equivalence is the state of two SNOMED CT concept codes or post coordinated expressions having the same meaning Concept equivalence can occur when a post coordinated expression has the same meaning as a pre coordinated concept code or when two different post coordinated expressions have the same meaning 9 8 Conceptld A SNOMED CT Identifier that uniquely identifies a Concept meaning us Example For the meaning named Pneumonia disorder the Conceptid is 233604007 man Note Field name in SNOMED CT Release Format 1 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 95 9 9 Concepts table A table that includes all SNOMED CT concept codes Each concept code is represented by a single row ag Note Component Table name in SNOMED CT Release Format 1 9 10 Core Core has different meanings depending on context A core component is a SNOMED CT Component released by the IHTSDO and the core namespace is the namespace used for SCTIDs released by the HTSDO It is policy that all core components have SCT Ds from t
12. 35 HAS DEFINITIONAL MANIFESTATION ccccccsceeeeeeeeeeeeeeeeeeeeesaeeeseeeeeseaeeeseneeeeaas 35 OCCURRENCE uti nal AL ee ae 36 FINDING METHOD tieccectits anpeant aad aa 36 FINDING INFORMER aa a a a aa rana aaa aA T E TENi 36 Attributes used to define Procedure CONCEptS oocoocccccnnnoccccnnnononcccnnnncanccnnn nro nc cnn rca 37 PROCEDURE SITE 2 a a adn 39 PROCEDURE MORPHOLOGY iiair ia ieia rra 41 METHOD tacto tos dde loe ae e bs nS ate 42 PROCEDURE DEVOE a r rl latina 42 ACCESS AA A ie ee et 44 DIRECT SUBS TANG Ess ati deta 45 PRIORI oe iaa 45 HAS FOCUS a e ae 45 HAS INTENTE camara at 46 RECIPIENT CATEGORY cen ii ate 46 REVISION STATUS stina tiaa aa te a aa a ar iaa 46 ROUTE OF ADMINISTRATION 2c ccceceeeeeeeeeceeeeeeeeeeeeaaeeeeeeeeseaaeeeseaeeseeaeeseeaaeeeeaees 47 SURGICAL APPROAC Hiciste ek eyed 47 USING SUBSTANC Eei aaaea e a a aaraa piar aa a a a 47 USINGSENERG Y Sirisa oaa o a asa a steven E A INE 48 Direct and indirect OBjSCtS iie aeiiae aiii 48 Attributes used to define Evaluation Procedure concepts esssssesssssrisssrerrsssrrrrrssrernnsns 48 HAS SPECIMEN awiinaii denial ate a ane eect 49 COMPONEN Tissot Ae ea ita AG ate ities ees 49 TIMEASRECT aa cece reece cere 50 PROPERTY Mae ee eae ee ne a eee edd 50 SCALE PE aa 50 MEASUREMENT METHO D coonocccnncccccnoncnonnncccnnnnnnnnnccconnnn a cnn nn cnn nan n nr mcr narran cnn 50 Attributes used to define Specimen CONCEPTS cococccccccocccinnoccconncononnan
13. are released using two tables Subsets Table e Each row in this table describes one release of a Subset e This table includes SNOMED CT Subsets that are packaged together in the Subset Members table e Subset Members Table e Each row in this table represents one member of a Subset The member may be a Concept or a Description e One or more Subsets may be packaged together in this table 2002 2011 The International Health Terminology Standards Development Organisation 82 SNOMED CT User Guide January 2011 6 5 Cross Mappings 6 5 1 Introduction Cross Mappings enable SNOMED CT to effectively reference other terminologies and classifications Each cross map matches SNOMED CT concepts with another coding scheme that is called the target scheme The Cross Mapping mechanism enables the distribution of Cross Maps from SNOMED Clinical Terms in a common structure The cross mapping structure enables e Automatic mapping from one SNOMED CT Concept to a single appropriate matching code in the Target Scheme e Automatic mapping from one SNOMED CT Concept to a single collection of codes in a Target Scheme that together represent the same Concept e Manual choice from a set of options for mapping a SNOMED CT Concept to a Target Scheme with several possible ways of representing the same or similar Concepts For Future Use The cross mapping structure does not enable e Mapping from post coordinated collections of SNOMED C
14. differentiate the concept from its immediate supertype s A concept which is not sufficiently defined is primitive For example if the concept Red car is defined as is a car and color red it is sufficiently defined but the same definition applied to the Concept Red sports car is primitive 9 48 Subset A group of components e g Concepts Descriptions or Relationships that share a specified common characteristic or common type of characteristic Subsets represent information that affects the way the components are displayed or otherwise accessible within a particular realm specialty application or context 9 49 Synonym A Term that is an acceptable alternative to the Preferred Term as a way of expressing a Concept Synonyms allow representations of the various ways a concept may be described Synonyms and Preferred Terms unlike FSNs are not necessarily unique More than one concept might share the same Preferred term or Synonym 2002 2011 The International Health Terminology Standards Development Organisation 104 SNOMED CT User Guide January 2011 9 50 Top level concept code A Concept Code that is directly related to the Root Concept Code by a single Relationship of the Relationship Type is a All Concept Codes except for metadata concepts are descended from at least one Top Level Concept Code via at least one series of Relationships of the Relationship Type Is a 9 51 Top level metadata code A Concept Cod
15. does not represent the fact that it is an infection codes starting with A or that it is due to staphylococcus A490 Staphylococcal infection unspecified The use of meaningless identifiers differs from the approach taken by some other coding systems and classifications For example the first character of an ICD10 code indicates the general classification that it falls within 2002 2011 The International Health Terminology Standards Development Organisation 20 SNOMED CT User Guide January 2011 No artificial limitation on concept granularity e Typical approaches to meaningful coding impose limits on both the number of levels of specificity i e the length of the code and the number of options at each level i e the number of different symbols that can be used in each character position 3 2 Descriptions S Concept descriptions are the terms or names assigned to a SNOMED CT concept Term in this context means a phrase used to name a concept A unique Descriptionld identifies a description Multiple descriptions might be associated with a concept identified by a Conceptld Example Some of the descriptions associated with Conceptld 22298006 Fully Specified Name Myocardial infarction disorder Descriptionld 751689013 e Preferred term Myocardial infarction Descriptionld 37436014 e Synonym Cardiac infarction Descriptionld 37442013 e Synonym Heart attack Descriptionld 37443015 e Syno
16. not a kind of measurement Of course several of the routine procedures carried out during a physical examination involve measurements of properties such as height weight vital signs range of motion deep tendon reflexes etc However the interpretation of primary observations as being normal or abnormal is not considered a kind of measurement since normality is not an inherent property quality or attribute that can be measured 2002 2011 The International Health Terminology Standards Development Organisation 90 SNOMED CT User Guide January 2011 but rather a second level interpretation of where the primary value lies relative to a range determined externally to the individual 8 4 Structure of the SNOMED Clinical Terms Identifier SCTID 8 4 1 SCTID Data Type The SCTID data type is a 64 bit integer which is subject to the following constraints e Only positive integer values are permitted The minimum permitted value is 100 000 6 digits The maximum permitted value is 999 999 999 999 999 999 18 digits Asaresult of rules for the partition identifier and check digit many integers within this range are not valid SCTIDs S 8 4 2 SCTIDs and Extensions If the partition identifier indicates that the SCTID is part of an Extension the next seven digits from the right are a namespace identifier see SCTID for an Extension Component Namespace identifiers are allocated to organizations which areauthorized to i
17. of asthma was not intended to represent the first time a patient had asthma but rather the first time a patient presented to their GP with asthma EPISODICITY has been removed from existing concepts and is no longer used in pre coordinated definitions It can still be used in post coordination as a qualifier S 7 2 ONSET and COURSE retired In earlier releases there were two attributes named ONSET and COURSE These were retired because they could not be used reproducibly While ONSET was intended to specify the rapidity of onset or the temporal pattern of presentation for a given condition it was easily confused with the attribute COURSE used to represent the duration of a condition There was not consistent agreement between observers making this distinction 7 3 Dose form values moved The concept 105904009 Type of drug preparation product and its subtypes were moved to the Qualifier value hierarchy as of the July 2007 release 105904009 Type of drug preparation qualifier value better represents these concepts because they are not products 7 4 Renaming the context situation hierarchy The hierarchy named 243796009 situation with explicit context situation was called context dependent category until the July 2006 release The hierarchy was renamed to better describe the meanings in this hierarchy S 7 5 Domain change for measurement evaluation attributes In releases prior to July 200
18. represents the device on which the method directly acts Table 30 Permissible values for DIRECT DEVICE Attribute Values Removal of arterial stent procedure Device 49062001 lt lt METHOD Removal action qualifier value e DIRECT DEVICE Arterial stent physical object 4 4 4 2 INDIRECT DEVICE This attribute models action done on something that is located in or on a device but is not done directly on the device itself Table 31 Permissible values for INDIRECT DEVICE Attribute Values Excision of vegetations from implanted mitral valve Device 49062001 lt lt procedure METHOD Excision action qualifier value DIRECT MORPHOLOGY Vegetation morphologic abnormality INDIRECT DEVICE Mitral valve prosthesis device physical object Procedure site Indirect Mitral valve structure body structure 2002 2011 The International Health Terminology Standards Development Organisation 44 SNOMED CT User Guide January 2011 cc Note In the above example the vegetation is being excised The mitral valve prosthesis is where the excised vegetation is located but the mitral valve prosthesis itself is not excised Thus mitral valve prosthesis is the INDIRECT DEVICE man Note The attribute INDIRECT DEVICE is infrequently needed When using this attribute a second look is advisable to be sure it is needed 4 4 4 3 USING DEVICE This attribute refers to
19. second and third digits from the right of the SCTID Partition id Partition identifier 9 33 Postcoordinated expression Representation of a clinical meaning using a combination of two or more concept identifiers is referred to as a post coordination Some clinical meanings may be represented in several different ways SNOMED CT technical specifications include guidance for transforming logical expressions to a common canonical form Example SNOMED CT includes the following concepts Fracture of bone conceptld 125605004 FINDING SITE conceptld 363698007 Bone structure of femur conceptld 181255000 SNOMED CT also includes a pre coordinated concept for this disorder Fracture of femur conceptld 71620000 Itis possible to represent fracture of femur in different ways 71620000 pre coordinated expression and 125605004 363698007 181255000 post coordinated expression Post coordinated Post coordination Postcoordinated Postcoordination 9 34 Precoordinated expression Representation of a clinical meaning using a single concept identifier is referred to as a pre coordination In constrast expressions that contain two or more references to concepts identifiers are said to be post coordinated O 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 101 Precoordinated Pre coordination Precoordinated Precoordinated expression Precoordination 9 35 Primitiv
20. the Relationships table are commonly referred to as the core tables The association of a set of Descriptions and a set of Relationships to each Concept is implemented using the Conceptld which is the primary or foreign key in the three tables RelationshipID ConceptlD DescriptionID ConceptID1 E sa ConceptStatus DescriptionStatus RelationshipType FullySpecifiedName ConceptID ConceptID2 CTV3ID Term CharacteristicType fe SNOMEDID D DescriptionType Refinability IsPrimitive InitialCapitalStatus RelationshipGroup LanguageCode Figure 12 SNOMED CT table structure 6 2 1 The Concepts Table The Concepts Table contains all the concepts in SNOMED CT Each concept is represented by one row of the table Each row of the Concepts Table contains the following fields 2002 2011 The International Health Terminology Standards Development Organisation Structure and Technology Considerations 79 SNOMED CT concepts are identified by their Conceptlds and all information about a SNOMED CT concept is ultimately linked to the Conceptld Conceptld is the primary key of the Concepts Table The original SNOMED RT identifier and original CTV3 identifier for each concept that originated in those terminologies Any newly created SNOMED CT concept is assigned a SNOMED RT identifier and a CTV3 identifier This allows users of SNOMED CT to work with legacy data coded with SNOMED RT or CTV3 codes The FullySpecifiedName fi
21. the inactive hierarchy This also means that the former confusing distinction between active and current no longer is required Active and current now mean the same thing and inactive and non current also now mean the same thing S 5 18 3 Namespace concept These codes have integer valued names that are the Extension namespace identifiers that have been assigned S 5 19 Record artifact A Record artifact is an entity that is created by a person or persons for the purpose of providing other people with information about events or states of affairs In general a record is virtual that is it is independent of its particular physical instantiation s and consists of its information elements usually words phrases and sentences but also numbers graphs and other information elements Record artifact need not be complete reports or complete records They can be parts of larger Record artifact For example a complete health record is a Record artifact that also may contain other Record artifact in the form of individual documents or reports which in turn may contain more finely granular Record artifact such as sections and even section headers 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 75 5 20 Core metadata concept Subtypes of Core metadata concept provide structural information for the core release data including concepts des
22. the instrument or equipment utilized to execute an action USING DEVICE is used when the device is actually used to carry out the action that is the focus of the procedure If the device is simply the means to access the site of the procedure then USING ACCESS DEVICE is used instead of USING DEVICE Table 32 Permissible values for USING DEVICE Attribute Values Core needle biopsy of larynx procedure Device 49062001 lt lt METHOD Biopsy action qualifier value USING DEVICE Core biopsy needle device physical object Procedure site Direct Laryngeal structure body structure 4 4 4 4 USING ACCESS DEVICE This attribute specifies the instrument or equipment used to access the site of a procedure Table 33 Permissible values for USING ACCESS DEVICE Attribute Values Device 49062001 lt lt Arthroscopic synovial biopsy procedure METHOD Biopsy action qualifier value USING ACCESS DEVICE Arthroscope device physical object Procedure site Direct Structure of synovial tissue of joint body structure 4 4 5 ACCESS This attribute describes the route used to access the site of a procedure It is used to distinguish open closed and percutaneous procedures 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 45 Table 34 Permissible values for ACCESS Attribute Values Surgical access valu
23. to complement the core content of the SNOMED CT International Release One example of the Extension mechanism is for extensibility of SNOMED CT for the specialized terminology needs of an organization Goals of Extensions are to 2002 2011 The International Health Terminology Standards Development Organisation Structure and Technology Considerations 83 Provide a structure where these Extensions maintain unique identification across organizations for data transmission and sharing but share a common structure for ease in application development and so that subsets can be constructed over a combination of International Release and extension content e Define a structure so that it is easy to submit include use and migrate terminology developed as part of an extension into the International Release content When content overlaps the scope of SNOMED CT it should be submitted to your IHTSDO National Release Center for consideration so that other SNOMED CT users can also take advantage of this work Using the extension structure can also helporganizations transfer responsibility for terminology to the IHTSDO or to another organization subject to the terms of the Affiliate License 6 7 SNOMED CT applications and services SNOMED Clinical Terms is a terminological resource that can serve many roles in healthcare software applications The IHTSDO supplies content that can be loaded into these applications but it does NOT supply any of t
24. 000 lt lt MEASUREMENT METHOD Laboratory procedure categorized by method 127789004 lt og Note Meaning of Allowable Values Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship S 4 5 1 HAS SPECIMEN This attribute specifies the type of specimen on which a measurement or observation is performed Table 46 Permissible values for HAS SPECIMEN 4 5 2 COMPONENT This attribute refers to what is being observed or measured by a procedure Table 47 Permissible values for COMPONENT Attribute Values Substance 105590001 lt lt Q Protein measurement procedure Observable entity 363787002 lt lt Q COMPONENT Protein substance Cell structure 4421005 lt lt Q Organism 410607006 lt lt Q 2002 2011 The International Health Terminology Standards Development Organisation 50 SNOMED CT User Guide January 2011 4 5 3 TIME ASPECT This attribute specifies temporal relationships for a measurement procedure Table 48 Permissible values for TIME ASPECT 4 5 4 PROPERTY This attribute specifies the kind of property being measured e g concentration Table 49 Permissible values for PROPERTY
25. 002 lt lt Event 272379006 lt lt Organism 410607006 lt lt Substance 105590001 lt lt Physical object 260787004 lt lt Physical force 78621006 lt lt Pharmaceutical biologic product 373873005 lt lt Q only SNOMED CT Concept 138875005 CAUSATIVE Organism 410607006 lt lt AGENT Substance 105590001 lt lt Physical object 260787004 lt lt Physical force 78621006 lt lt Pharmaceutical biologic product 373873005 lt lt Q only SNOMED CT Concept 138875005 DUE TO Clinical Finding 404684003 lt Event 272379006 lt AFTER Clinical Finding 404684003 lt lt Procedure 71388002 lt lt SEVERITY Severities 272141005 lt lt Q CLINICAL COURSE Courses 288524001 lt lt Q EPISODICITY Episodicities 288526004 lt lt Q INTERPRETS Observable entity 363787002 lt lt Laboratory procedure 108252007 Evaluation procedure 386053000 lt HAS INTERPRETATION Findings values 260245000 lt lt PATHOLOGICAL PROCESS Autoimmune 263680009 Infectious process 441862004 ES HAS DEFINITIONAL MANIFESTATION Clinical finding 404684003 lt lt O 2002 2011 The International Health Terminology Standards Development Organisation 30 SNOMED CT User Guide January 2011 Defining Attribute Subsumed Allowable Values Attribute OCCURRENCE Periods of life 282032007 lt
26. 004 lt lt SPECIMEN SOURCE IDENTITY Blood donor Community 133928008 lt lt person Device 49062001 lt lt Catheter tip specimen specimen Environment 276339004 lt lt SPECIMEN SOURCE IDENTITY Catheter tip device physical object 4 7 Attributes used to define Body structure concepts Just one attribute is used in Anatomy namely Laterality This attribute is detailed below Table 58 Attributes for Body structure concepts summary table Defining Attribute Permissible Values LATERALITY Side 182353008 lt O 2002 2011 The International Health Terminology Standards Development Organisation 54 SNOMED CT User Guide January 2011 Man Note Permissible values for this attribute include the descendants of the concept listed except for super category grouper concepts S 4 7 1 LATERALITY This attribute provides information on whether a body structure is left right bilateral or unilateral It is applied only to bilaterally symmetrical body structures which exist on opposite sides of the body Table 59 Permissible values for LATERALITY Attribute Values Side 182353008 lt Left kidney structure body structure e LATERALITY Left qualifier value 4 8 Attributes used to define Pharmaceutical Biologic Product concepts Table 60 Approved Pharmaceutical Biologic Product attributes summary Defining Attribute Allowable Values HAS ACTIVE INGREDIEN
27. 2002 2011 The International Health Terminology Standards Development Organisation 46 SNOMED CT User Guide January 2011 4 4 9 HAS INTENT This attribute specifies the intent of a procedure Table 38 Permissible values for HAS INTENT Attribute Values Diagnostic bronchoscopy procedure HAS INTENT Diagnostic intent qualifier value S 4 4 10 RECIPIENT CATEGORY This attribute specifies the type of individual or group upon which the action of the procedure is performed For example it can be used in blood banking procedures to differentiate whether the procedure was performed on the donor or the recipient of a blood product In other words RECIPIENT CATEGORY is Donor for medical or surgical procedure person if the subject of the record is the donor It is not used for a procedure where the subject of the procedure is someone other than the subject of record Table 39 Permissible values for RECIPIENT CATEGORY Attribute Values Person 125676002 lt lt Social service interview of family procedure Family 35359004 lt lt e RECIPIENT CATEGORY Family social concept Community 133928008 lt lt Donor for medical or surgical procedure 105455006 lt lt Group 389109008 lt lt S 4 4 11 REVISION STATUS This attribute specifies whether a procedure is primary or a revision Table 40 Permissible values for REVISION STATUS Attribute Values Primary operation
28. 2011 The International Health Terminology Standards Development Organisation Basic Components of SNOMED CT 19 Procedure Procedure on lymph node Biopsy of lymph node More aggregation lEJSp BSIUI D SJO Surgical biopsy of lymph node Excisional biopsy of lymph node Figure 1 Multiple levels of granularity 3 1 2 Concept identifiers Each SNOMED CT Concept has a permanent unique numeric identifier which is known as the Conceptld The sequence of digits in a Conceptid does not convey any information about the meaning or nature of the Concept The meaning of Conceptis represented in human readable forms by Descriptions and in a computer processable form by Relationships with other Concepts The advantages of meaningless identifiers include e Identifier permanence without undermining interpretation e In contrast to maintain consistency a meaningful code may need to change to reflect revised understanding of the nature of a disorder e Enabling multiple aspects of meaning to be represented in the same way e A meaningful code can only represent part of meaning of a complex concept For example staphylococcal pneumonia is an infection a respiratory disorder and a disorder caused by staphylococcus but only one of these aspects can be represented by a code based hierarchy Thus in the J in the CD10 code J152 Pneumonia due to staphylococcus represents that fact that this is a respiratory disorder but
29. 261424001 lt lt Primary repair of inguinal hernia procedure Revision value 255231005 lt lt aoa STATUS Primary operation qualifier Part of multistage procedure 257958009 lt lt Revision of knee arthroplasty procedure REVISION STATUS Revision value qualifier value 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 47 4 4 12 ROUTE OF ADMINISTRATION This attribute allows representation of the route by which a procedure introduces a given substance into the body The domain for this attribute is the sub hierarchy below Administration of substance via specific route procedure 433590000 Table 41 Permissible values for ROUTE OF ADMINISTRATION Attribute Values Inhaled drug administration procedure Route of administration value 284009009 lt lt ROUTE OF ADMINISTRATION By inhalation route qualifier value 4 4 13 SURGICAL APPROACH This attribute specifies the directional relational or spatial access to the site of a surgical procedure The domain for SURGICAL APPROACH is descendants of Surgical procedure procedure 387713003 Table 42 Permissible values for SURGICAL APPROACH Attribute Values Intranasal ethmoidectomy procedure SURGICAL APPROACH Intranasal approach qualifier value Procedural approach 103379005 lt lt Q Abdominal hysterectomy proced
30. 4 Description A human readable phrase or name Term associated with a particular SNOMED CT concept code Each of the descriptions in SNOMED CT is given a separate row in the Descriptions Table Each Description is assigned a unique Descriptionid and connects a Term and a Concept SNOMED CT description 9 15 Descriptionld A SNOMED CT Identifier that uniquely identifies a Description us Note Field name in SNOMED CT Release Format 1 9 16 Descriptions table A data table consisting of rows each of which represents a Description ag Note Component Table name in SNOMED CT Release Format 1 9 17 Dialect A language modified by the vocabulary and grammatical conventions applied to the anguage of a particular geographical or cultural environment 9 18 Enabled application A software application designed to support the use of SNOMED CT 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 97 SNOMED CT enabled application SCT enabled application SNOMED CT enabled application SNOMED CT enabled application SNOMED enabled application SNOMED CT application SNOMED CT application 9 19 Extension A data table or set of data tables that is created in accordance with the structures and authoring guidelines applicable to SNOMED CT An extension is ordinarily edited maintained and distributed by an organization other than the IHTSDO components in extensions are identified using ext
31. 404684003 lt lt Fostviratdisordar disorder Procedure 71388002 lt lt AFTER Viral disease disorder This example can be paraphrased as every post viral disorder occurs after some viral disease S 4 3 5 DUETO This attribute is used to relate a Clinical finding directly to its cause If a clinical finding merely predisposes to or worsens another disorder rather than causing it directly then the more general attribute ASSOCIATED WITH is used instead Table 9 Permissible values for DUE TO Attribute Values Clinical Finding 404684003 lt Cheilitis due to atopic dermatitis disorder Event 272379006 lt IS A Cheilitis disorder DUE TO Atopic dermatitis disorder 4 3 6 CAUSATIVE AGENT This attribute identifies the direct causative agent of a disease It does not include vectors e g a mosquito that transmits malaria Table 10 Permissible values for CAUSATIVE AGENT Attribute Values Organism 410607006 lt lt Bacterial endocarditis disorder Substance 105590001 lt lt CAUSATIVE AGENT Superkingdom Bacteria organism Physical object 260787004 lt lt Physical force 78621006 lt lt Fentanyl allergy disorder Pharmaceutical biologic product 373873005 lt lt Q CAUSATIVE AGENT Fentanyl substance only I SNOMED CT Concept 138875005 Electrical burn of skin disorder CAUSATIVE AGENT Electricit
32. 590001 lt lt Pharmaceutical biologic product 373873005 lt lt PRIORITY Priorities 272125009 lt lt Q HAS FOCUS Clinical finding 404684003 lt lt Procedure 71388002 lt lt HAS INTENT Intents nature of procedure values 363675004 lt RECIPIENT CATEGORY Person 125676002 lt lt Family 35359004 lt lt Community 133928008 lt lt Donor for medical or surgical procedure 105455006 lt lt Group 389109008 lt lt REVISION STATUS Primary operation 261424001 lt lt Revision value 255231005 lt lt Part of multistage procedure 257958009 lt lt ROUTE OF ADMINISTRATION Route of administration value 284009009 lt lt SURGICAL APPROACH Procedural approach 103379005 lt lt Q USING ENERGY Physical force 78621006 lt lt USING SUBSTANCE Substance 105590001 lt lt 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 39 cc Note Meaning of Allowable Values Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship man Note Attributes should be grouped with the METHOD attribute to w
33. 9 six attributes were approved for use for measurement procedure only For the July 2009 release the domain for these attributes was expanded to evaluation procedure See Measurement procedures and laboratory procedures on page 89 for a definition and full discussion of evaluation procedure and measurement procedure 2002 2011 The International Health Terminology Standards Development Organisation 86 SNOMED CT User Guide January 2011 7 6 Move of findings to events In January 2006 a number of concepts from the Clinical finding hierarchy were moved to the Event hierarchy The attributes used to define those concepts when they were descendants of Clinical finding were retained after the concepts were moved to the Event hierarchy Additional editorial policies for the use of attributes in the Event hierarchy have yet to be established 2002 2011 The International Health Terminology Standards Development Organisation Miscellaneous Topics 87 Chapter 8 Miscellaneous Topics Topics Terms Prefaced with Symbols e Negation Measurement procedures and laboratory procedures e Structure of the SNOMED Clinical Terms Identifier SCTID 2002 2011 The International Health Terminology Standards Development Organisation 88 SNOMED CT User Guide January 2011 8 1 Terms Prefaced with Symbols There are some terms in SNOMED CT that are prefaced with a symbol in square brackets These concept c
34. CE for precoordinated content e Clarification of the range for attributes in the PROCEDURE DEVICE role hierarchy Change to the range for SPECIMEN SOURCE IDENTITY July 2009 Changes to the range of attributes that take an anatomical value Changes to the range for FINDING SITE e Changes to the range for PROCEDURE SITE attributes e Changes to the range for SPECIMEN SOURCE TOPOGRAPHY e Changes to the range for INTERPRETS and HAS INTERPRETATION e Changes to the range for PATHOLOGICAL PROCESS e Changes to the domain for the six attributes previously identified for use with Measurement procedures e Changes to the range for LATERALITY 2002 2011 The International Health Terminology Standards Development Organisation Preface 13 Notes Updated presentation of attribute ranges allowable values to reflect machine readable concept model work Changed method of generating document from MS Word to DITA Overall appearance change and revised order of front matter Revised figures and diagrams so they can be shared SVG images Added appendix Changes and historical notes Changed Role hierarchies to Attribute hierarchies Updated and clarified wording in several sections Added information about the metadata hierarchy and related changes which are part of the January 2010 Technology Previews and will be incorporated into a future International Release Added paragraph on allowable domains in post coordinated expressions Revised seve
35. E thelial tei 79 PBG paa e Seah eA ie de 80 Component History INtrOductiOn cceecccceeeeeeeeeeeeeeeeeeeaeeeseaeeeeeaaeeseeeeeesaaeeneneeess 80 History NIOCHANISIM sticcccscctisiteyeecactariecteduteteevtanettegvecusts reverend ETES EEEN EEA atestado 80 SNOMED GT SUDSOTS soda ii iia 81 Introd cese i a i di 81 Subset table and file StruCtureS 0 cccccceeeseeeeeneeeeeeeeeceaeeeeeeeeeseaeeeeeaaeeseeeeeseaaeeneaeeess 81 Gross Mapp S a r a ies 82 IMTFOGUCTION vitrina ET E T E E O TE E EA EA E RE 82 Cross Mapping tableS cooonccnnninidinonccnnncccnnonccnnnoncnnnnn conan cn nana cc corran nn nc n nn 82 EXTENSIONS iii A Mads eine eee da 82 SNOMED CT applications and services ooonicccnnnncnnncccnnnccnnnnncccnn rra nnn cnn rn 83 Chapter 7 Changes and historical not8S ooooonnnnncicccccnnnnnnnncmmmmmos 84 EPISODICITY no longer modeled in active COnteNt oooooccnincccnnnncconncccccnnccnnnonccnancnnn arc n cnn 85 ONSET and COURSE retired riata te er aaa ii 85 Dose form values MOVED eera e aR AAEE E ARA EAEE iiA 85 Renaming the context situation hierarChY oononcccnnnnnnicinnnnnccocnnnnnncccnnnnonnna nn nan nnnnn cnn nn nnnn nn rana 85 Domain change for measurement evaluation attributes oooonnnidnnininnnnnnnnnnncnnnnnccncnconccnnnnnnns 85 Move of findings to ESVenNtS cooomocccccnnonncccnnnonncccnnnnnnnnncnnnnnncn eE EEA ENEAS REEERE EESE E Ert 86 Chapter 8 Miscellaneous TopiCS ccccccccccccccccccccn
36. ED CT User Guide January 2011 1 1 1 2 1 3 G 1 4 Purpose This document describes the content structure and terminology of SNOMED CT It is intended to provide new as well as experienced users with an overview and illustrations of SNOMED CT s capabilities and uses from a content perspective As such it explains the content and the principles used to model the terminology Who should read this guide The intended audience for the User Guide includes clinical personnel business directors software product managers and project leaders who are involved in the acquisition implementation and use of SNOMED CT and SNOMED CT enabled applications in their organizations While an information technology background may be helpful it is not required to benefit from this User Guide Technical professionals who support the implementation of SNOMED CT or who develop systems that will use SNOMED CT may find this guide helpful in providing a high level overview of the terminology structure and content However for detailed technical guidance technical professionals should consult the SNOMED CT Technical Reference Guide TRG and SNOMED CT Technical Implementation Guide TIG as well as other applicable technical documentation described in the Inventory of Documentation Notation used in this document The following notation is used in this User Guide to represent key types of SNOMED CT information SNOMED CT Concept names are generally repr
37. EMPORAL CONTEXT spaa a a a a a a Ea 58 SUBJECT RELATIONSHIP CONTEXT oooococcccccccconcnconccononnnnnanononnnnnnnnnnnccnnncn nana nnnnccnnns 59 Attributes used to define Event concepts ooccccccnnocccccnononccccnnnnoncnonanano nc cnn nan cnc cnn rn cnn 60 Attributes used to define Physical Object concepts ooooconnccccicccccnnoccnconcconannnnnnncccnnnnc nana cocino 61 Relationship Groups in SNOMED CT inocccnccccnnoncnnnnncononnnnnnnnnononnnn nano nc cnn cn nnnn nn cnn cn anar nn nnnncnns 61 Chapter 5 Hicrarehles ii iaa 63 Summary of Top Level Hierarchi8S ooocconnncninnncnnnononnncccnncccnnnn nc cnn nn cc 64 Top Level COnCe pts cccceecccecececeeeneeeceeeeeeaeeeceaeeeseaaeecaeesseaaaeseaeeeeeaaeesseneeseaaaesseneeess 64 Top Level Metadata er a n e T AAE ERRE EER 64 oale ae llave aare iia ti n 64 A o a anA AAA E A AA AE TAE NAA o ANTAA AE AT AE 65 Situation with explicit context cece ce cececeececeeeeceaeeeeeeeeceaaeeeeeeeecaaeesseaeeseeaeseeeaeeseeeeeeeaeeeeaees 65 Observable Style tos da to 66 Bady SIC ai a pia 66 A a ea Oe ee a 66 SUBSTANCE sais ia teed Cobia ates AA east ds eee dcte aad endo 67 Pharmaceutical Diologic PrOGuct sirenos seniii ekeen nn non nnnn cnn nn AORERE nn 67 Virtual Medicinal Product VWMP ooooonnoccccnnnnocccccconncnnnnncnncnnnnncnnnonnnnn nano nn n rr nnnn rra 67 Virtual Therapeutic Moiety VTM oooonnocccccnnnoccccnnnnconcnnncnnnnncncnnnnancnnn nano nn cnn nan nnnnrnnnnns 67 Product CategO Vicio
38. OSCON iii ec ada 20 PRETATION SIDS 2 5 a aee AENEAS a iD 21 Relationships and concept definitiONS o oococnnnnnniccnnnnnaccccnnnnccnccnnn narco 21 IS A relations APS 22 Attribute relationships reres neon eiiiai te a EN E eE ia e 23 Chapter 4 Attributes Used in SNOMED CT sssssnsssnnnnnnnnnnnnnnnnnnnnnnn 25 INTOQUCION citada 26 DOMAIN iii E E A deel viabedetcevleeestth 26 Allowable domains in post coordinated ExpressiQNS coooonnocccccnonocccccnanoncncncnananccnnnnna 26 E O 26 Attribute Hierarchies in SNOMED CTioonnniccconociconocccnonnnnnnnnnnnnnncn nono n cnn nc cra rra cnn 27 Attribute hierarchies used in modeling Procedures oococoonocccccnonocccccccnnonccncnnnannncnnnnna 27 Attribute hierarchy used in modeling Clinical FINdINQS oooonncccnncnnnnncccnnncconnccccnanccinn 28 Attributes used to define Clinical Finding COnCepts c cccceecceceseeeeeeeeeceaeeeeeneeesseeeteneeeeas 28 PINDING SMED 30 2002 2011 The International Health Terminology Standards Development Organisation Contents 3 ASSOCIATED MORPHOLOG Y erreta aa aaura aana toada ta paaa aA aaea TAS EAEE AEO AE ANa E Ha 30 ASSOCIATED WiT Hound deat analyte 31 ARTES td do etc ad ado da e edo e A 31 DUETO a lr Icod 32 CAUSATIVE AGENTE e ai 32 SEVERA dt 32 C N CAD COURSE cuca lada ion Abs aude coo inna 33 EPISODIO ea 34 INTERPRETO cmd a eke ed ett ee eb aes 34 HAS INTERPRETATION ii eian atl Cece da a adobo 34 PATHOLOGICAL PROCE SS a Traa raa aaa iaa
39. OURCE IDENTITY Person 125676002 lt lt Family 35359004 lt lt Community 133928008 lt lt Device 49062001 lt lt Environment 276339004 lt lt og Note Meaning of Allowable Values Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship 4 6 1 SPECIMEN PROCEDURE This attribute identifies the procedure by which a specimen is obtained 2002 2011 The International Health Terminology Standards Development Organisation 52 SNOMED CT User Guide January 2011 Table 53 Permissible values for SPECIMEN PROCEDURE Attribute Values Procedure 71388002 lt Urine specimen obtained by clean catch procedure specimen SPECIMEN PROCEDURE Urine specimen collection clean catch procedure Specimen from stomach obtained by total gastrectomy specimen SPECIMEN PROCEDURE Total gastrectomy procedure 4 6 2 SPECIMEN SOURCE TOPOGRAPHY This attribute specifies the body site from which a specimen is obtained Table 54 Permissible values for SPECIMEN SOURCE TOPOGRAPHY Attribute Values Anatomical or acquired body structure 442083009 Cervix cytologic material specimen lt lt SPECIMEN SOURCE TOPOGRAPHY Cervix uter
40. Procedure Clinical finding Pharmaceutical biologic product Situation with explicit context Event Specimen and Physical object In addition LATERALITY is a defining attribute applied to Body structure concepts Other hierarchies such as Social context Substance Organism and Observable entity are not assigned attributes and instead are considered supporting hierarchies Concepts from the supporting hierarchies can serve as the attribute values for the concept definitions of the main hierarchies This section describes the approved attributes used in SNOMED CT There are many other attributes in SNOMED CT subtypes of Unapproved attribute attribute which have not yet been evaluated thoroughly and approved for use S 4 2 Attribute Hierarchies in SNOMED CT Selected SNOMED CT attributes have a hierarchical relationship to one another known as attribute hierarchies In an attribute hierarchy one general attribute is the parent of one or more specific subtypes of that attribute Concepts defined using the more general attribute can inherit concepts modeled with the more specific subtypes of that attribute S 4 2 1 Attribute hierarchies used in modeling Procedures Three groups of attributes are organized as a simple two level hierarchy The three top level attributes are PROCEDURE SITE JPROCEDURE DEVICE and PROCEDURE MORPHOLOGY Each has a sub attribute to repres
41. Procedure 71388002 lt Q only Finding context value 410514004 lt lt Q Procedure 71388002 lt lt Q Observable entity 363787002 lt Q only Context values for actions 288532009 lt lt Q Temporal context value 410510008 lt lt Q SUBJECT RELATIONSHIP CONTEXT Person 125676002 lt lt Q o Note Meaning of Allowable Values Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship O 2002 2011 The International Health Terminology Standards Development Organisation 56 SNOMED CT User Guide January 2011 4 9 1 Context The meaning conveyed by a SNOMED CT code in a medical record is affected by the context in which it is recorded For instance the code for breast cancer might be used to indicate a family history of breast cancer a past history of breast cancer or a current diagnosis of breast cancer Each of these three meanings differs in regard to the context in which breast cancer is being described Family history of breast cancer refers to breast cancer occurring in a family member of a patient Past history of breast cancer indicates that the breast cancer occurred in the patient at some time in the past and it is not n
42. RECT Attribute Values Removal of catheter from brachial vein procedure Anatomical or acquired body structure 442083009 lt lt METHOD Removal action qualifier value DIRECT DEVICE Catheter device physical object Procedure site Indirect Structure of brachial vein body structure Removal of calculus of urinary bladder procedure METHOD Removal action qualifier value DIRECT MORPHOLOGY Calculus morphologic abnormality Procedure site Indirect Urinary bladder structure body structure S 4 4 2 PROCEDURE MORPHOLOGY PROCEDURE MORPHOLOGY is the attribute used to specify the morphology or abnormal structure involved in a procedure This attribute subsumes the more specific attributes DIRECT MORPHOLOGY and INDIRECT MORPHOLOGY that should be used if possible see below DIRECT MORPHOLOGY is used when the procedure method acts directly on the morphologic abnormality INDIRECT MORPHOLOGY is used when the procedure method acts directly on something else e g a device substance or anatomical structure that is associated with the morphologic abnormality The more general attribute PROCEDURE MORPHOLOGY is used when defining general concepts that subsume both kinds of sub concepts Table 25 Permissible values for PROCEDURE MORPHOLOGY Morphologically abnormal structure 49755003 lt lt La Hematoma calculus foreign body blood clot embolus and some othe
43. ROCEDURE DEVICE Catheter device physical object 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 43 When the device is the direct object of the action METHOD the attribute DIRECT DEVICE is used If the action is done indirectly to the device that is the action is done to something that is located in or ona device but is not done directly to the device itself then the attribute INDIRECT DEVICE is used If the device is used to carry out the action then the attribute USING DEVICE is used If the device is used to access the site of the action then the attribute USING ACCESS DEVICE is used us Note The permissible values for attributes in the PROCEDURE DEVICE role hierarchy include Device physical object and its descendants However there are a limited number of products in SNOMED CT which are devices that also deliver drugs These concepts descend from Drug device combination product product which is a descendant of both Device physical object and Pharmaceutical biologic product product Therefore although they carry the hierarchy tag of product they are valid values for attributes in the PROCEDURE DEVICE role hierarchy Example Removal of drug coated stent procedure e METHOD Catheter device physical object e DIRECT DEVICE Drug coated stent product 4 4 4 1 DIRECT DEVICE This attribute
44. Range notations lt lt this code and descendants lt descendants only lt descendants only stated except for supercategory groupers this code only lt Q descendants only when in a qualifying relationship lt Q only descendants only and only allowed in a qualifying relationship 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 61 For guidance and examples on the use of these attributes and value ranges to define events see the section on clinical findings 4 11 Attributes used to define Physical Object concepts Table 71 Approved Physical Object attributes summary Defining Attribute Allowable Values HAS ACTIVE INGREDIENT Substance 105590001 lt lt man Note Allowable values for this attribute includes the concept listed and its descendants A limited number of concepts e g drug eluting stents reside in the Pharmaceutical biologic product hierarchy and the Physical object hierarchy These concepts are all under Drug device combination product product This is the domain of HAS ACTIVE INGREDIENT within the Physical Object hierarchy Editorial policies for the use of other attributes in the Physical object hierarchy generally outside this particular domain have yet to be established 4 12 Relationship Groups in SNOMED CT Multiple attributes and their values can be grouped together into Relationship grou
45. T Substance 105590001 lt lt HAS DOSE FORM Type of drug preparation 105904009 lt lt Man Note Permissible values for these attributes include the concepts listed and their descendants S 4 8 1 HAS ACTIVE INGREDIENT This attribute indicates the active ingredient of a drug product linking the Pharmaceutical biologic product hierarchy to the Substance hierarchy Table 61 Permissible values for HAS ACTIVE INGREDIENT Attribute Values ISubstance 105590001 lt lt Naproxen 500mg tablet product HAS ACTIVE INGREDIENT Naproxen substance 2002 2011 The International Health Terminology Standards Development Organisation 4 8 2 HAS DOSE FORM This attribute specifies the dose form of a product Attributes Used in SNOMED CT 55 Table 62 Permissible values for HAS DOSE FORM Attribute Values Type of drug preparation 105904009 lt lt Digoxin 0 1mg capsule product HAS DOSE FORM Oral capsule qualifier value 4 9 Attributes used to define Situation with Explicit Context concepts Table 63 Approved Situation attributes summary Defining Attribute ASSOCIATED FINDING FINDING CONTEXT ASSOCIATED PROCEDURE PROCEDURE CONTEXT TEMPORAL CONTEXT Allowable Values Clinical finding 404684003 lt lt Q Event 272379006 lt lt Q Observable entity 363787002 lt Q only Link assertion 416698001 lt Q only
46. T Concepts to a single Target Code or a specific collection of Target Codes e g mapping a combination of a disorder qualified by severity or a procedure qualified by urgency e Mapping from multiple fields in a patient record to a specific Target Code that represents a combination of characteristics e g mapping a combination of a disorder procedure and the age and sex of the patient to a single group code This structure is based on the practical experience of the Cross Mapping tables of Clinical Terms Version 3 CTV3 one of SNOMED CT s source terminologies 6 5 2 Cross Mapping tables The SNOMED CT structure to support Cross Mapping includes three tables e Cross Map Sets Table Each row in this table represents a Target Scheme for which Cross Maps are available e Cross Maps Table Each row in this table represents one option for mapping a SNOMED CT Concept to a target code or set of codes in the Target Scheme e Cross Map Targets Table Each row in this table represents a code or set of codes in the Target Scheme which provides a mapping for one or more SNOMED CT Concepts 6 6 Extensions SNOMED CT is a deep and detailed clinical terminology with a broad scope However some groups of users will need additional Concepts Descriptions or Subsets to support national local or organizational needs The Extension mechanism is a structure that enables authorized organizations to add Concepts Descriptions Relationships and Subsets
47. Topics iS Summary of Top Level SNOMED CT concepts are organized into hierarchies There are two Hierarchies special Codes referred to as the Root Concept Code and the Root Clinical finding Metadata Code They are at the root of the two hierarchies that contain Procedure all Concept Codes in SNOMED CT The root named SNOMED CT Situation with explicit context Observable entity Body structure Organism Substance Pharmaceutical biologic product Specimen Physical object Physical force Event Environments and geographic locations Social context Staging and scales Qualifier value Special concept Record artifact Core metadata concept Foundation metadata concept Linkage concept Concept subsumes is the supertype of the top level concepts and all the concepts beneath them their subtypes and the root named SNOMED CT Model component subsumes all the metadata components As the hierarchies are descended the concepts within them become increasingly specific or granular A brief description of the content in each hierarchy is given below ag Note The Root Metadata Code and the hierarchy under it have been included in a technology preview release but have been omitted from the official January 2010 nternational Release of SNOMED CT The technology preview provides SNOMED CT ina new release format called Release Format 2 RF2 as a draft for trial use Subtype or child concepts are the desc
48. ackground Clinical knowledge is not a prerequisite The TRG contains reference material related to the current release of SNOMED CT and includes file layouts field sizes required values and their meanings and high level data diagrams It can be used to install and use SNOMED SNOMED CT Technical Implementation Guide TIG The TIG is intended for SNOMED CT implementers such as software designers The TIG assumes information technology and software development experience Clinical knowledge is not required although some background is helpful to understand the application context and needs The TIG contains guidelines and advice about the design of applications using SNOMED CT and covers topics such as terminology services entering and storing information and migration of legacy information SNOMED CT User Guide The User Guide is intended for clinical personnel business directors software product managers and project leaders information technology experience though not necessary can be helpful The User Guide is intended to explain SNOMED CT s capabilities and uses from a content perspective It explains the content and the principles used to model the terminology 1 6 1 Additional Documentation The following supplementary documentation is also included in English only as part of the International Release of SNOMED CT e Technical Reference Guide e User Guide Editorial Guide 2002 2011 The International Health Termi
49. al abnormality and the anatomical structure in which it is located are to be modeled as direct objects for the METHOD Removal action qualifier value Grafts that become attached via in growth of capillaries fibroblasts and or other cells or tissues would also be regarded as biologically connected and therefore modeling their removal would include the anatomical structure as a direct object of the action The anatomical structure is not to be modeled as a direct object of a removal only when the procedure does not necessarily involve removal also of part of the anatomy examples include removals of things such as a foreign body a catheter a renal calculus or a mechanical implant like a pacemaker S 4 4 1 2 PROCEDURE SITE INDIRECT This attribute describes the anatomical site which is acted upon but is not the direct object of the procedure The site is indirectly acted on by the procedure Usually in these procedures there is another value that is the direct object of the action Exceptions concepts that do not specify a direct object but only an indirect object are usually general groupers such as Arm implantation procedure meaning implantation of something into the arm since the thing implanted could be either a device or a substance material 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 41 Table 24 Permissible values for PROCEDURE SITE INDI
50. and needs to be reversed To achieve the correct inferences in queries and reasoning systems Situation with explicit context concept codes with a finding context of known absent or subtypes thereof should have their Is a relationships reinterpreted by reversing the Concept and Concepi2 of the is a relationships This is a temporary fix and will be addressed systematically in a future release so that such ad hoc solutions will not be necessary G 8 3 Measurement procedures and laboratory procedures Measurements are observations that designate the value of a property quality or attribute that is inherent in the individual or population or their specimens by proxy according to specified rules Although measurement is generally considered to be the observation of a quantitative value for a quality or attribute measurements need not necessarily result in a numeric or ordinal result In other words detection detected not detected and identification selection of one or more possibilities from a specified set by detecting their presence or absence are considered types of measurement procedures This is admittedly a broad definition but does require that measurement procedures be done according to pre determined rules and that they specify the property quality or attribute that is being measured Measurement can definitely be done by physical examination techniques as well as by laboratory techniques but physical examination by itself is
51. and other stakeholders It is intended to be complete but has not been formally approved as a final version Draft Indicates that the document or resource is a draft version It may be incomplete and has not been approved in a final version This edition of the document is configured to use US English The PDF version of this draft is formatted to be printed on US Letter paper ug Note This is one of a several large documents that are regularly revised by the IHTSDO Therefore for the sake of the environment please think carefully before deciding to print the entire document 1 5 Additional information Further information about SNOMED CT is available by contacting IHTSDO 2002 2011 The International Health Terminology Standards Development Organisation 10 SNOMED CT User Guide January 2011 1 5 1 IHTSDO Contact Details Web www ihtsdo org Email support ihtsdo org Address IHTSDO Rued Langgaards Vej 7 5te DK 2300 Copenhagen S Denmark Tel 45 3644 8736 Fax 45 4444 8736 1 6 Inventory of Documentation The following essential SNOMED CT documentation is currently available in both English and Spanish versions as part of the International Release of SNOMED CT from the International Health Terminology Standards Development Organization IHTSDO SNOMED CT Technical Reference Guide TRG The TRG is intended for SNOMED CT implementers such as software developers The TRG assumes an information technology b
52. and the subject who smokes is the patient s father Table 69 Permissible values for SUBJECT RELATIONSHIP CONTEXT Concept Values Person 125676002 lt lt Q Father smokes situation ASSOCIATED FINDING Smoker finding SUBJECT RELATIONSHIP CONTEXT Father of subject person 2002 2011 The International Health Terminology Standards Development Organisation 60 SNOMED CT User Guide January 2011 4 10 Attributes used to define Event concepts Table 70 Approved Event attributes summary Defining Attribute Subsumed Allowable Values Attribute ASSOCIATED VTE Clinical Finding 404684003 lt lt Procedure 71388002 lt lt Event 272379006 lt lt Organism 410607006 lt lt Substance 105590001 lt lt Physical object 260787004 lt lt Physical force 78621006 lt lt Pharmaceutical biologic product 373873005 lt lt Q only SNOMED CT Concept 138875005 CAUSATIVE Organism 410607006 lt lt AGENT Substance 105590001 lt lt Physical object 260787004 lt lt Physical force 78621006 lt lt Pharmaceutical biologic product 373873005 lt lt Q only SNOMED CT Concept 138875005 DUE TO Clinical Finding 404684003 lt Event 272379006 lt AFTER Clinical Finding 404684003 lt lt Procedure 71388002 lt lt OCCURRENCE Periods of life 282032007 lt maa Note Meaning of Allowable Values
53. ards Development Organisation Overview 15 Chapter 2 Overview Topics e What is SNOMED CT e SNOMED CT uses 2002 2011 The International Health Terminology Standards Development Organisation 16 SNOMED CT User Guide January 2011 2 1 What is SNOMED CT SNOMED Clinical Terms SNOMED CT is a comprehensive clinical terminology that provides clinical content and expressivity for clinical documentation and reporting It can be used to code retrieve and analyze clinical data SNOMED CT resulted from the merger of SNOMED Reference terminology SNOMED RT developed by the College of American Pathologists CAP and Clinical Terms Version 3 CTV3 developed by the National Health Service NHS of the United Kingdom The terminology is comprised of concepts terms and relationships with the objective of precisely representing clinical information across the scope of health care Content coverage is divided into hierarchies which include Table 3 Top Level Concepts Clinical finding Physical force Procedure Event Observable entity Environment or geographical location Body structure Social context Organism Situation with explicit context Substance Staging and scales Pharmaceutical biologic product Physical object Specimen Qualifier value Special concept Record artifact Linkage concept 2 2 SNOMED CT uses Health care software applicat
54. bute relationships An attribute Relationship is an association between two concepts that specifies a defining characteristic of one of the concepts the source of the Relationship Each Attribute Relationship has a name the type of Relationship and a value the destination of the Relationship For example The combination of the attribute Relationships and is a relationships associated with a concept represent the logical definition of that concept The logical concept definition includes one or more supertypes represented by is a relationships and a set of defining Attributes that differentiate it from the other concept definitions us Example Since pneumonia is a disorder of the lung the logical definition of the concept Pneumonia disorder in SNOMED CT includes the following Relationship The Attribute Finding site is assigned the value Lung structure body structure Finding site Lung structure body structure The full definitions of the concepts Pneumonia disorder Infective pneumonia disorder and Bacterial pneumonia disorder are shown below Each line represents a defining Attribute with a value lisa pneumonitis e isa lung consolidation e associated morphology inflammation e associated morphology consolidation e finding site lung structure Figure 4 Definition of Pneumonia disorder e lisa infectious disease of
55. cc Ad Rd 68 Actual Medicinal Products AMPS oooonoccccnnnnnoccccncnnconcccnnnnoncncnnnnnnnnncnnnnnn cc nc nnnnnnnncnnnns 68 oO O td Mach aaa tease ee Seta 71 Physical Object anii ir a land aed Meee iene 71 Physical o ea 71 o ATE E ee E cerca er renee O TO 71 Environments and geographic lOCAtIONS oonnoocccninnnnicinnnnnccccnnnnnncccnnnnnnnnn cnn nn nnnnn cnn cnn rra 72 Social CONTE reaa A di 72 Stagingyand scal S iii a Aa 73 Qualifier Valles chitin rd ie tie Aa th ee ae Ata 73 2002 2011 The International Health Terminology Standards Development Organisation Contents 5 Special CONCOPL ai A A A 73 NET i aiaa A E N aaa ad 74 INACTIVE Comep a E A See is 74 Namespace concepte rin a E E EA A E EE 74 Record artifact ninio ii e Va Aaa dh eee een eae en N NAN 74 Core metadata CONCEDL cccceececeeeeeeceaeceeeeeeceaaeseeeeecaaaeseaeeecaaesseaeeseeaeseeeeeesseeesseaeeneaees 75 Foundation metadata CONCBPt cocccccnnnncccccnnnnccccccnnnonnncononnn nn cnn nn nnn cnn nan nnn nn rra r nn rra 75 Linkage CONC A A A aA iia 75 LAA do ants 75 AttribUtO ouoidc dd ALE dada dida 75 Chapter 6 Structure and Technology Considerations 77 INTOQUCION ueiian EA E A R 78 SNOMED CT table Sni iaa a iiaia vice ier ean tind aaa EE A EAE een eee 78 The Concepts Table aeaieie oernaam ea Reia e na A eund Aasai maia aot AASIAA Po Aa daia Daa 78 The Descriptions Table iaa REEE EEEN EAEEREN E 79 The Relationships Tables ici
56. ccconecenencnnononnnnnnnos 87 Terms Prefaced with Symbols ccccccesceeceeeeeeeneeeeeeeeeeeaaeeseeeeesesaeeseeeeeesaeeeseneeecsaeeeteaeeesaas 88 Ne Oia S A A S 88 Negation and Contexte iii ei eth eae tee ati 89 Known Problems with NegatiON ooononccccnnnnoccccnonncccccnnnnonnnncnnnnnnnn nn non nnnnn cnn rr nan n rca ranas 89 Measurement procedures and laboratory procedureS coooooccccccnncccccccnanoncnnnnnnnancncn nana n cnn nnnnnons 89 O 2002 2011 The International Health Terminology Standards Development Organisation 6 SNOMED CT User Guide January 2011 Structure of the SNOMED Clinical Terms Identifier SCTID 0 cccceeseeeeeeeeeseeeeeeeeeeeeeeees 90 SCTID Data Type unica A i eee 90 SETIDS and Extensions Ai dad dee ete ahh thes 90 Chapter 9 User Guide GloSSary cccccccccccccccccccccccccncconecconennnnnnnnons 91 Chapter 10 SNOMED CT Background cccccccccccccccccccccccccnccnnncnnnos 105 Acknowledgments of Contributors to SNOMED CTO ccccccceeeeeseeeeeeeenaeeeeeseneeeeeesaaas 106 2002 2011 The International Health Terminology Standards Development Organisation Preface 7 Chapter 1 Preface Topics e Purpose Who should read this guide e Notation used in this document e Status Additional information e Inventory of Documentation e Document History Copyright Notice 2002 2011 The International Health Terminology Standards Development Organisation 8 SNOM
57. criptions and relationships S 5 21 Foundation metadata concept Subtypes ofthe Foundation metadata concept provide supporting metadata and structural information for derivative release structures including Reference Sets 5 22 Linkage concept Linkage concept codes are intended to link two or more other codes to each other to express compositional meanings All concept codes that can be used as a Relationship Type are included under Linkage concept The ones approved for use are the Concept Model Attributes Implementation guidance is as yet quite limited for the other Linkage concept codes Use of them should be regarded as non standard tentative and experimental requiring extra care The Linkage concept hierarchy contains the sub hierarchies Link assertion Attribute Note For the RF2 release format Linkage concept will no longer be a top level hierarchy but will instead become a subclass of SNOMED CT model component 5 22 1 Link assertion The Link assertion sub hierarchy enables the use of SNOMED CT concepts in HL7 statements that assert relationships between statements Currently this content supports the UK NHS Connecting for Health requirements for encoding of Statement relationships for the implementation of HL7 Version 3 messaging in the UK realm Examples of Link assertion concepts e Has reason e Has explanation 5 22 2 Attribute Concepts that descend from thi
58. d circumstances significant to healthcare Content includes such areas as family status economic status ethnic and religious heritage life style and occupations These concepts represent social aspects affecting patient health and treatment Some sub hierarchies of Social context and concepts typical of those sub hierarchies are shown in the following examples Canary islands geographic location California geographic location Rehabilitation department environment Intensive care unit environment S 5 15 Social context Examples Ethnic group ethnic group Afro Caribbean ethnic group Estonians ethnic group Occupation occupation Bank clerk occupation Carpenter general occupation Person person e Employer person Boyfriend person Caregiver person Religion philosophy religion philosophy Hinduism religion philosophy Orthodox Christian religion religion philosophy Economic status social concept Middle class economic status social concept 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 73 5 16 Staging and scales This hierarchy contains such sub hierarchies as Assessment scales assessment scale which names assessment scales and Tumor staging tumor staging which names tumor staging syste
59. dialect The Preferred Term is a common word or phrase used by clinicians to name that concept us Example the concept 54987000 repair of common bile duct procedure has the Preferred Term choledochoplasty to represent a common name clinicians use to describe the procedure 2002 2011 The International Health Terminology Standards Development Organisation 3 3 Basic Components of SNOMED CT 21 ug Note Unlike the Fully Specified Name FSN the Preferred Terms need not be unique Occasionally the Preferred Term for one concept may also be a Synonym or the Preferred Term for a differentconcept oe Example e Cold sensation quality qualifier value has a preferred term of Cold Common cold disorder also has a synonym of Cold In both cases cold represents a common clinical phrase used to capture the meaning of the concept 3 2 1 3 Synonym A synonym represents a term other than the FSN or Preferred Term that can be used to represent a concept in a particular language or dialect og Example Synonyms of the concept 22298006 myocardial infarction disorder in English include e cardiac infarction Description id 37442013 heart attack Description id 37443015 infarction of heart Description id 37441018 The Preferred Term for this concept in English is myocardial infarction Description id 37436014 wg Note Synonyms like Preferred Terms are not requ
60. e An expression which may be just a single concept code is primitive when its logic definition does not sufficiently express its meaning so that its subtypes can be computably recognized A concept code s logic definition is made up of its defining relationships to other concept codes via attributes and is a relationships Primitive concept codes also do not have the defining relationships that would be needed to computably distinguish them from their parent or sibling concepts For example if the Concept Red sports car is defined as is a car color red this is Primitive but the same definition applied to the Concept Red car is sufficiently defined 9 36 Qualifying characteristic An attribute value relationship associated with a concept code to indicate to users that it may be applied to refine the meaning of the code The set of qualifying relationships provide syntactically correct values that can be presented to a user for post coordination Example Revision status First revision is a possible qualifying characteristic of Hip replacement A qualifying characteristic is contrasted with a defining characteristic lt is referred to in CTV3 as a Qualifier Qualifier 9 37 Realm A sphere of authority expertise or preference that influences the range of components required or the frequency with which they are used A Realm may be a nation an organization a professional discipline a specialty or an individual
61. e Changes to range for PROCEDURE SITE and FINDING SITE and SPECIMEN SOURCE TOPOGRAPHY Added section on use of attribute for Physical object hierarchy Updates to Examples O 2002 2011 The International Health Terminology Standards Development Organisation 12 SNOMED CT User Guide January 2011 Version Notes July 2007 Updates to reflect transfer of IP to the International Health Terminology Standards Development Organization e Removal of references to College of American Pathologists CAP derivative products Information provided on anticipated changes to Attributes used to define Procedure concepts e ACCESS e APPROACH e Changes to value for HAS DOSE FORM for Pharmaceutical biologic products January Changes to Attributes used to define Procedure concepts 2008 New attribute SURGICAL APPROACH e Retired APPROACH Changes to description for attribute RECIPIENT CATEGORY e Changes to the range for ASSOCIATED FINDING and additional guidance on the use of ASSOCIATED FINDING and ASSOCIATED PROCEDURE in post coordinated expressions July 2008 Changes to domain for Attribute ROUTE OF ADMINISTRATION e Discussion on the References Table Update on D M X V SO Q and EDTA concepts in an appendix e Discussion of Negation was added to an appendix January Changes to the range for attributes in the ASSOCIATED WITH role hierarchy for precoordinated 2009 content e Changes to the range for DIRECT SUBSTAN
62. e by clinicians In many cases it is a shortened version of the Fully Specified Name e Synonyms Other terms that can be used to name a concept The large numbers of synonyms in SNOMED CT provide flexibility of expression e LanguageCode This field in the Descriptions Table associates each description with a particular language or dialect such as UK English Spanish etc 6 2 3 The Relationships Table This table contains the relationships between SNOMED CT concepts A Relationship in the table is stored as a combination of three concepts in the order Conceptld1 RelationshipType Conceptld2 This is represented in the table by the following fields e Relationshipld The Relationshipld uniquely identifies each set of three concepts in a relationship and serves as the primary key of this table e Conceptld1 The first concept in the relationship e Relationship Type This is the type of relationship either the IS A relationship or an attribute or a Historical or Additional relationship that exists between two concepts e Conceptld2 The target concept in the relationship Either the Parent concept in an IS A relationship or the concept that represents the value assigned in an attribute relationship The most common Relationship Type used in SNOMED is the IS A relationship a k a subsumption relationship hierarchical relationship supertype subtype relationship or parent child relationship When an IS A relationship is listed in the Relat
63. e e References Table The Component History Table includes any changes to SNOMED CT Components Concepts Descriptions Subsets Cross Maps Significant changes generally require retirement of the component and addition of O 2002 2011 The International Health Terminology Standards Development Organisation Structure and Technology Considerations 81 replacement component s The retirement and addition are recorded in the history records Changes designated as minor require only a history record to record the change The References Table provides a reference from an inactive SNOMED CT component Concept moved to an Extension Description Subset or Cross Map Set to a component that is current for the Release in which the first component is made inactive The type of reference indicates the nature of the relationship between the two components This is similar to the information that historical relationships provide for inactive Concepts 6 4 SNOMED CT Subsets 6 4 1 Introduction A Subset refers to a set of Concepts Descriptions or Relationships that are appropriate to a particular language dialect country specialty organization user or context In its simplest form the Subset Mechanism is a list of SNOMED identifiers SCTIDs Each SCTID refers to one component of SNOMED CT that is a member of the Subset called a Subset Member As an analogy think of SNOMED CT as a book A Subset is like an index entry pointing to a se
64. e Domain is the hierarchy to which a specific attribute can be applied The Domain of the attribute ASSOCIATED MORPHOLOGY is the Clinical finding hierarchy A Procedure cannot have an ASSOCIATED MORPHOLOGY A Procedure has a PROCEDURE MORPHOLOGY S 4 1 2 Allowable domains in post coordinated expressions The concept model provides constraints for attributes that are used as defining relationships both in distributed SNOMED CT content so called pre coordinated definitions and in post coordinated expressions as described in the document Abstract Logical Models and Representational Forms available at www ihtsdo org our standards technical documents The domain or starting concept to which qualifying relationships are applied in post coordinated expressions may be more general than the domain of defining relationships defined in the concept model as long as the resulting post coordinated concept expression as a whole satisfies the concept model constraints For example the concept model constraint for SURGICAL APPROACH requires that its domain be Surgical procedure procedure 387713003 When SURGICAL APPROACH is used in a qualifying relationship in post coordinated expressions the starting domain may be a general procedure if the resulting expression satisfies the concept mode constraint In other words when SURGICAL APPROACH is added to a general procedure as a qualifying relationship the pos
65. e that is directly related to the Root Metadata Code by a single Relationship of the Relationship Type is a All Metadata Concept Codes are descended from at least one Top Level Metadata Concept Code via at least one series of Relationships of the Relationship Type ls a ag Note Most of the data in the metadata hierarchy is only relevant to Release Format 2 Therefore this concept may not be present in Release Format 1 files 2002 2011 The International Health Terminology Standards Development Organisation SNOMED CT Background 105 Chapter 10 SNOMED CT Background Topics G e Acknowledgments of Contributors to SNOMED CT 2002 2011 The International Health Terminology Standards Development Organisation 106 SNOMED CT User Guide January 2011 10 1 Acknowledgments of Contributors to SNOMED CTO SNOMED CT was originally created by the College of American Pathologists SNOMED CT has been created by combining SNOMED RT and a computer based nomenclature and classification known as Clinical Terms Version 3 formerly known as the Read Codes Version 3 which was created on behalf of the U K Department of Health and is Crown copyright The HTSDO also acknowledges the contributions of The American Academy of Ophthalmology for the ophthalmology related portions of this work SNODENTS the Systematized Nomenclature of Dentistry copyright 1998 American Dental Association Used with permission SNOVET the Sys
66. ecessarily present now Current diagnosis of breast cancer indicates that the breast cancer is present now and in this patient These differences are important for data retrieval because it would be incorrect when searching for patients with breast cancer to retrieve those who merely have a family history of breast cancer S 4 9 2 Default Context When a SNOMED CT code appears in a record without any explicitly stated context that code is considered to have a default context The default is soft in that it can be over ridden by information carried in the structure of the record or its information model The default context for a clinical finding code implies that the finding has actually occurred vs being absent that it applies to the subject of the record the patient and that it is occurring currently or occurred at a past time that is given by a date time record linked to the code The default context for a procedure code implies that the procedure was completed that it was performed on the subject of the record the patient and that it was done at the present time or in the past at a time that is given by a date time record linked to the code 4 9 3 Axis Modifiers The six attributes used to define situation codes permit explicit rather than default representation of various contexts These attributes can change the meaning of a clinical finding or procedure code in a way that changes the hierarchy or axis of the c
67. ed in the International Release but it can still be used in post coordination as a qualifier Table 13 Permissible values for EPISODICITY 4 3 10 INTERPRETS This attribute refers to the entity being evaluated or interpreted when an evaluation interpretation or judgment is intrinsic to the meaning of a concept This attribute is usually grouped with the HAS INTERPRETATION attribute Table 14 Permissible values for INTERPRETS Attribute Values Observable entity 363787002 lt lt LPecisa sent Muscle tone imamg Laboratory procedure 108252007 lt lt INTERPRETS muscle tone observable entity Evaluation procedure 386053000 lt lt HAS INTERPRETATION Decreased qualifier value Abnormal glucose level finding INTERPRETS Glucose measurement procedure HAS INTERPRETATION Outside reference range qualifier value ug Note For concepts in the Measurement finding subhierarchy the value for INTERPRETS should be an Evaluation procedure or a Laboratory procedure rather than an Observable entity 4 3 11 HAS INTERPRETATION This attribute is grouped with the attribute INTERPRETS and designates the judgment aspect being evaluated or interpreted for a concept e g presence absence degree normality abnormality etc 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 35 Table 15 P
68. eld appears in both the Concepts Table and the Descriptions Table In the Concepts Table it serves to provide a human readable name for each concept e The ConceptStatusfield indicates whether a concept is in active use or retired This field flags concepts that have been retired so that data encoded with these concepts can be properly accessed and retrieved long after it has been coded e The sPrimitivefield indicates whether or not a concept has been flagged as primitive during the modeling process This flag can be useful in advanced applications that take advantage of the description logic features of SNOMED CT A more detailed description of fully defined and primitive concepts can be found inUser Guide Glossary on page 91 6 2 2 The Descriptions Table This table relates the various terms used to name a single SNOMED CT concept The Descriptions Table includes the following fields Descriptionld Each description has a unique Descriptionld which serves as the primary key of this table e DescriptionType This field indicates if the description is one of three types e The Fully Specified Name FSN A term that uniquely and unambiguously identifies each concept in a human readable way just as the Conceptld uniquely identifies each term in a machine readable way There is only one Fully Specified Name for each concept in each edition The Preferred Term Intended to represent the common way a concept is expressed in natural languag
69. endant concepts of Supertype or parent concepts ag Example Streptococcal arthritis disorder is a subtype of Bacterial arthritis disorder Supertype concepts are the ancestor concepts of Subtype concepts gg Example Bacterial arthritis disorder is a supertype of Streptococcal arthritis disorder 2002 2011 The International Health Terminology Standards Development Organisation 64 SNOMED CT User Guide January 2011 S 51 Summary of Top Level Hierarchies Si 5 1 1 Top Level Concepts Table 72 Top Level Concepts Clinical finding Physical force Procedure Event Observable entity Environment or geographical location Body structure Social context Organism Situation with explicit context Substance Staging and scales Pharmaceutical biologic product Physical object Specimen Qualifier value Special concept Record artifact Linkage concept 5 1 2 Top Level Metadata Table 73 Top Level Metadata Core metadata concept Foundation metadata concept S 5 2 Clinical finding Concepts in this hierarchy represent the result of a clinical observation assessment or judgment and include both normal and abnormal clinical states Examples of Clinical finding concepts e Clear sputum finding Normal breath sounds finding Poor posture finding The Clinical finding
70. ension SCTIDs which are structured to ensure that they do not collide with other SCT Ds and can be traced to an authorized originator SNOMED CT extension 9 20 Fully defined See Sufficiently defined 9 21 Fully specified name A term unique among active Descriptions in SNOMED CT that names the meaning of a Concept code in a manner that is intended to be unambiguous and stable across multiple contexts man Note Field name in SNOMED CT Release Format 1 9 22 Hierarchy An ordered organization of concept codes linked together through is a relationships Concept codes linked to their more general parent concept codes directly above them in a hierarchy Concept codes with more general meanings are usually presented as being at the top of the hierarchy and then at each level down the hierarchy code meanings become increasingly more specific or specialized Formally a hierarchy is represented as a directed acyclic graph 2002 2011 The International Health Terminology Standards Development Organisation 98 SNOMED CT User Guide January 2011 9 23 History mechanism The history mechanism is the information distributed with SNOMED CT designed to track the history of changes to its logic definitions and descriptions The history mechanism is supported by two distribution tables Component History Table e References Table 9 24 SNOMED CT Identifier A unique integer identifier applied to each SNOMED CT component Concept Desc
71. ent the direct object and another to represent the indirect object In addition PROCEDURE DEVICE can be specialized by the attributes USING DEVICE and JUSING ACCESS DEVICE PROCEDURE DEVICE attribute hierarchy PROCEDURE DEVICE e DIRECT DEVICE O 2002 2011 The International Health Terminology Standards Development Organisation 28 SNOMED CT User Guide January 2011 e INDIRECT DEVICE USING DEVICE USING ACCESS DEVICE PROCEDURE MORPHOLOGY attribute hierarchy PROCEDURE MORPHOLOGY DIRECT MORPHOLOGY INDIRECT MORPHOLOGY PROCEDURE SITE attribute hierarchy PROCEDURE SITE PROCEDURE SITE DIRECT PROCEDURE SITE INDIRECT S 4 2 2 Attribute hierarchy used in modeling Clinical Findings ASSOCIATED WITH attribute hierarchy ASSOCIATED WITH e AFTER DUE TO CAUSATIVE AGENT S 4 3 Attributes used to define Clinical Finding concepts Table 4 Approved Clinical Finding attributes summary Defining Attribute Subsumed Allowable Values Attribute FINDING SITE Anatomical or acquired body structure 442083009 lt lt ASSOCIATED MORPHOLOGY Morphologically abnormal structure 49755003 lt lt 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 29 Defining Attribute Subsumed Allowable Values Attribute ASSOCIATED MITA Clinical Finding 404684003 lt lt Procedure 71388
72. ept Code Special concept and its subclass codes provide a place for concept codes that are no longer active in the terminology The subclasses of Special concept are Navigational concept Inactive concept 2002 2011 The International Health Terminology Standards Development Organisation 74 SNOMED CT User Guide January 2011 5 18 1 Navigational concept These concept codes are to be used only as nodes in a Navigation Subset They are not suitable for data recording or aggregation The subclasses of Navigational concept have the following characteristics They have no is a subtypes They have no is a supertypes other than Navigational concept e They may be associated with other concept codes by the use of Navigation Links S 5 18 2 Inactive concept These concept codes are no longer current within SNOMED CT and should not be used for encoding data There is one hierarchical level which consists of these subclasses Reason not stated Duplicate Outdated Ambiguous Erroneous e Limited Moved elsewhere Each inactive concept code falls into one of these seven subclasses based upon its ConceptStatus value of 1 2 3 4 5 6 or 10 There is no further subclassing of inactive concepts Note that concept codes with a ConceptStatus value of 6 Limited were formerly considered active but are now inactive and are included in
73. er Guide January 2011 6 1 Introduction The structure and technology behind SNOMED CT enables organizations to implement it and integrate it into their own clinical and business processes and applications SNOMED CT offers additional capabilities to facilitate customization of an implementation to meet the unique requirements of an organization This section provides an introduction to SNOMED CT structure and technology highlighting its core and extended capabilities This overview is intended to provide project managers and others involved with SNOMED CT implementations a better understanding of technology requirements and support considerations for SNOMED CT implementation and maintenance Topics addressed include SNOMED CT data structure SNOMED CT data components and their relationships including the core table structure as well as e History e Subsets e Cross Mapping e Extensions SNOMED CT applications and services Detailed information for each topic is available in the SNOMED CT Technical Reference Guide TRG SNOMED CT Technical Implementation Guide TIG and the SNOMED CT Developer Toolkit See Inventory of Documentation on page 10 for descriptions of the content and target audiences for each available document 6 2 SNOMED CT tables SNOMED CT is distributed as a set of tab delimited text files that can be imported into a relational database The three tables shown below the Concepts table the Descriptions table and
74. ermissible values for HAS INTERPRETATION Attribute Values Decreased muscle tone finding INTERPRETS Muscle tone observable entity HAS INTERPRETATION Decreased qualifier value Findings values 260245000 lt lt Abnormal glucose level finding INTERPRETS Glucose measurement procedure HAS INTERPRETATION Outside reference range qualifier value 4 3 12 PATHOLOGICAL PROCESS This attribute provides information about the underlying pathological process for a disorder but only when the results of that process are not structural and cannot be represented by the ASSOCIATED MORPHOLOGY attribute For the July 2009 release two new values Infectious process qualifier value and Parasitic process qualifier value have been added to the range for PATHOLOGICAL PROCESS These were added to accommodate the change in the modeling of concepts in the Infectious disease disorder subhierarchy where the infectious aspect of the disease is now represented using PATHOLOGICAL PROCESS Table 16 Permissible values for PATHOLOGICAL PROCESS Attribute Values Autoimmune parathyroiditis disorder PATHOLOGICAL PROCESS Autoimmune qualifier value Autoimmune 263680009 Infectious process 441862004 lt lt Disease caused by parasite disorder PATHOLOGICAL PROCESS Parasitic process qualifier value Pathological process must not be used for value
75. es 309795001 lt lt Q Open removal of bile duct stent procedure ACCESS Open approach access qualifier value S 4 4 6 DIRECT SUBSTANCE This attribute describes the Substance or Pharmaceutical biologic product on which the procedure s method directly acts Table 35 Permissible values for DIRECT SUBSTANCE Attribute Values Substance 105590001 lt lt Injection of prostaglandin procedure Pharmaceutical biologic product 373873005 lt lt IMETHOD Injection action qualifier value DIRECT SUBSTANCE Prostaglandin substance Note As an editorial policy in the distribution form of the International Release Pharmaceutical biologic product product and its descendants are not used as values for DIRECT SUBSTANCE S 4 4 7 PRIORITY This attribute refers to the priority assigned to a procedure Table 36 Permissible values for PRIORITY Attribute Values Priorities 272125009 lt lt Q Emergency cesarean section procedure PRIORITY Emergency qualifier value S 4 4 8 HAS FOCUS This attribute specifies the Clinical finding or Procedure which is the focus of a procedure Table 37 Permissible values for HAS FOCUS Attribute Values Clinical finding 404684003 lt lt Cardiac rehabilitation assessment procedure Procedure 71388002 lt lt HAS FOCUS Cardiac rehabilitation regime therapy
76. esented using the Fully Specified Name in mixed case formatted as in the following example Example Peribronchial pneumonia disorder SNOMED CT Attribute names are represented in all capital letters formatted as in the following example Example FINDING SITE Status This guide contains parts and sections which differ in terms of the authority and status of their content Each section of the guide is marked to indicate its publication type and status using the symbols shown in Table 1 Document Types on page 9 and Table 2 Document Status on page 9 O 2002 2011 The International Health Terminology Standards Development Organisation Preface 9 Table 1 Document Types Standard A document or other resource that is intended to be authoritative This includes specifications of SNOMED CT content and release files Normative requirements for particular functions are also standards Guidance A document or other resource that is intended to provide advice or suggest possible approaches to particular requirement or subject area Table 2 Document Status Status Name and Description Standard Guidance Current Indicates that the document or resource is considered to be up to date S G and complete for the current release of SNOMED CT indicated by an explicitly stated version date or by the publication date Review Indicates that the document or resource has been released for review and comments from SNOMED CT users
77. he Substance it contains can be assigned to this level or to any of the subtypes of this level us Example Diazepam product O 2002 2011 The International Health Terminology Standards Development Organisation 68 SNOMED CT User Guide January 2011 All Virtual Medicinal Products VMP have a direct link to the Virtual Therapeutic Moiety VTM via an isa relationship Diazepam product a Oral form diazepam product Diazepam 5mg tablet product ne Figure 10 Example There are additional levels in the Pharmaceutical biologic product hierarchy that provide structure and organization For example some subtypes of VTM contain only Dose form information and not Strength og Example Concept with granularity between that of a VTM and VMP Parenteral form epinephrine product e Dose form Name 5 9 3 Product category A Product category concept supports a group of Pharmaceutical biologic product related by their functionality mechanism of action or therapeutic use Product category concepts typically describe common drug categories used in prescribing Examples of Product category concepts Sex hormone product product e Mineralocorticoid preparation product beta Blocking agent product Tissue plasminogen activator preparation product 5 9 4 Actual Medicinal Products AMPs Actual Medicinal Products can be represented in extensions
78. he core namespace SNOMED CT core Core table SNOMED CT core table SNOMED CT core file Core file 9 11 Core table Refers to the SNOMED CT Concept Relationship and Description Tables ag Note Component Table name in SNOMED CT Release Format 1 SNOMED CT core table 9 12 Cross map A Cross Map is a reference from a Concept code to a Cross Map Target Each Cross Map is represented as a row in the Cross Maps Table It links a single SNOMED CT concept code to one or more codes in a target classification such as ICD 9 CM or terminology A Concept code may have a single Cross Map or a set of alternative Cross Maps 9 13 CTV3ID A five character code allocated to a meaning or term in Clinical Terms Version 3 CTV3 previously known as Read Codes Each row in the SNOMED CT concepts table has a field for the corresponding concept code from CTV3 man Note Field name in SNOMED CT Release Format 1 2002 2011 The International Health Terminology Standards Development Organisation 96 SNOMED CT User Guide January 2011 Note The CTV3ID and SNOMEDID fields are no longer supported in Release Format 2 Instead a Simple map reference set is used to document the link between legacy codes and SNOMED CT ag Note The CTV3ID field should no longer be relied upon for mapping to and from the Read Codes Additional mapping work in the UK identified some anomalies and resulted development of more flexibility table for Read Code Mapping 9 1
79. he software itself User requirements for these software applications will vary according to way in which they are used Healthcare software applications usually address a particular set of requirements associated with one or more clinical and or business processes Detailed requirements for integrating SNOMED CT into a particular application inevitably depend upon intended uses the perceptions of users and the technical environments in which they are implemented The following examples illustrate a few possible types of implementation A SNOMED CT enabled clinical record system incorporating clinical data entry decision support links to knowledge bases sophisticated analysis order report message interfaces support for record communication or sharing etc A data warehouse storing and analyzing records expressed with SNOMED CT encoded concepts e A diagnostic departmental system sending reports that include SNOMED CT encoded concepts to other systems A hand held data collection device used for input of a limited range of frequently used coded concepts e A decision support system using SNOMED CT concepts to represent guidelines and protocols for distribution to other systems A system designed to enable the creation of queries for use in analysis of data held by various other systems some of which contain SNOMED CT encoded data e Acoding system mapping SNOMED CT encoded concepts entered manually or read from an electronic reco
80. hich they apply in the absence of a METHOD attribute attributes that are related to each other should be grouped The one exception is RECIPIENT CATEGORY because a single procedure code should not be pre coordinated in situations where more than one recipient category is involved Such complex statements should utilize two or more procedure codes that are placed into an appropriately structured information model 4 4 1 PROCEDURE SITE The PROCEDURE SITE attribute describes the body site acted on or affected by a procedure This attribute subsumes in an attribute hierarchy see Attribute Hierarchies in SNOMED CT on page 27 the more specific attributes Procedure site Direct and Procedure site Indirect that should be used if possible The anatomical site may be directly acted on Procedure site Direct or indirectly acted upon Procedure site Indirect When modeling procedures where the METHOD is Removal action or one of its subtypes e g Excision Surgical biopsy etc removals of the structure itself should use Procedure site Direct Removals of tissue lesions cysts tumors etc are considered to be removals of the site and should also use Procedure site Direct Removals of devices calculi thrombi foreign bodies and other non tissue entities from the structure should use Procedure site Indirect Table 22 Permissible values for PROCEDURE SITE Attribute Values Anatomical or acqu
81. his attribute is frequently used in conjunction with FINDING INFORMER Findings that specify that they were determined by examination of the patient e g On examination ankle clonus finding should have a value for both FINDING METHOD and FINDING INFORMER Table 19 Permissible values for FINDING METHOD Attribute Values Finding by palpation finding FINDING METHOD Palpation procedure Procedure 71388002 lt 4 3 16 FINDING INFORMER This attribute specifies the person or other entity from which the clinical finding information was obtained This attribute is frequently used in conjunction with FINDING METHOD 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 37 Table 20 Permissible values for FINDING INFORMER Attribute Values Complaining of a headache finding FINDING INFORMER Subject of record or other Performer of method 420158005 lt lt Subject of record or other provider of history 419358007 lt lt provider of history person On examination ankle clonus finding FINDING INFORMER Performer of method person It is accepted that an information model should permit identification of a particular individual who provides information FINDING INFORMER is not about the particular individual It is about the category or type of informer which is used to differentiate self reported sympto
82. i structure body structure Omentum biopsy sample specimen SPECIMEN SOURCE TOPOGRAPHY Omentum structure body structure S 4 6 3 SPECIMEN SOURCE MORPHOLOGY This attribute names the morphologic abnormality from which a specimen is obtained Table 55 Permissible values for SPECIMEN SOURCE MORPHOLOGY Attribute Values Morphologically abnormal structure 49755003 lt lt Specimen from cyst specimen SPECIMEN SOURCE MORPHOLOGY Cyst morphologic abnormality Specimen from wound abscess specimen SPECIMEN SOURCE MORPHOLOGY Abscess of wound morphologic abnormality 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 53 4 6 4 SPECIMEN SUBSTANCE This attribute names the type of substance of which a specimen is comprised Table 56 Permissible values for SPECIMEN SUBSTANCE Attribute Values Substance 105590001 lt lt Mid stream urine sample specimen SPECIMEN SUBSTANCE Urine substance Pancreatic fluid specimen specimen SPECIMEN SUBSTANCE Pancreatic fluid substance 4 6 5 SPECIMEN SOURCE IDENTITY This attribute names the type of individual group or physical location from which a specimen is collected Table 57 Permissible values for SPECIMEN SOURCE IDENTITY Attribute Values Person 125676002 lt lt Blood specimen from blood donor specimen Family 35359
83. ic Agent product ISA Product Category functionality Tissue Plasminogen Activator Preparation product Has active ingredient Alteplase product Alteplase substance Alteplase 10mg powder and solvent for injection solution vial product International Release Extensions Activase 10mg powder and Actilyse 10mg powder and solvent for injection solvent for injection solution vial solution vial US Drug Extension UK Drug Extension Figure 11 Pharmaceutical Biologic Product hierarchy structure 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 71 5 10 Specimen The Specimen hierarchy contains concepts representing entities that are obtained usually from a patient for examination or analysis Specimen concepts can be defined by attributes which specify the normal or abnormal body structure from which they are obtained the procedure used to collect the specimen the source from which it was collected and the substance of which it is comprised Examples of Specimen concepts Specimen from prostate obtained by needle biopsy specimen Urine specimen obtained by clean catch procedure specimen e Calculus specimen specimen Cerebroventricular fluid cytologic material specimen 5 11 Physical object Concepts in the Physical object hierarchy include natural and man made objects One use for these concepts is modeli
84. ierarchy This hierarchy was introduced as a top level hierarchy in order to clearly distinguish drug products products from their chemical constituents substances It contains concepts that represent the multiple levels of granularity required to support a variety of uses cases such as computerized provider order entry CPOE e prescribing decision support and formulary management The levels of drug products represented in the International Release include Virtual Medicinal Product VMP Virtual Therapeutic Moiety VTM and Product Category Additionally US and UK drug extensions have been developed which represent Actual Medicinal Products AMPs 5 9 1 Virtual Medicinal Product VMP The most granular level is the Virtual Medicinal Product VMP The VMP is a representation at the level of generality that would appear on a physician s prescription The product name strength and dose form are all represented in the Fully Specified Name This level can be used to support providers with drug ordering in CPOE and e prescribing use cases ug Example Diazepam 5mg tablet product Name Strength Dose form S 5 9 2 Virtual Therapeutic Moiety VTM The Virtual Therapeutic Moiety VTM level represents a more general level of granularity than the VMP level VTMs include the product name but not formulation dose or strength in the Fully Specified Name The HAS ACTIVE INGREDIENT attribute which relates the product to t
85. il observable entity is an observable Gray nails finding is a finding One use for Observable entity in a clinical record is to code headers on a template For example Gender observable entity could be used to code a section of a template titled Gender where the user would choose male or female Female gender would then constitute a finding 5 6 Body structure Body structure concepts include normal as well as abnormal anatomical structures Normal anatomical structures can be used to specify the body site involved by a disease or procedure Examples of Body structure concepts e Mitral valve structure body structure Uterine structure body structure Morphologic alterations from normal body structures are represented in the sub hierarchy Body structure altered from its original anatomical structure morphologic abnormality Examples of Body Structure altered from ts original anatomical structure concepts e Adenosarcoma morphologic abnormality e Polyp morphologic abnormality 5 7 Organism This hierarchy includes organisms of significance in human and animal medicine Organisms are also used in modeling the causes of diseases in SNOMED CT They are important for public health reporting of the causes of notifiable conditions and for use in evidence based infectious disease protocols in clinical decision support systems Sub hierarchies of
86. ions focus on collection of clinical data linking to clinical knowledge bases information retrieval as well as data aggregation and exchange Information may be recorded in different ways at different times and sites of care Standardized information improves analysis SNOMED CT provides a standard for clinical information Software applications can use the concepts hierarchies and relationships as a common reference point for data analysis SNOMED CT serves as a foundation upon which health care organizations can develop effective analysis applications to conduct outcomes research evaluate the quality and cost of care and design effective treatment guidelines Standardized terminology can provide benefits to clinicians patients administrators software developers and payers A clinical terminology can aid in providing health care providers with more easily accessible and complete information pertaining to the health care process medical history illnesses treatments laboratory results etc and thereby result in improved patient outcomes A clinical terminology can allow a health care provider to identify patients based on certain coded information in their records and thereby facilitate follow up and treatment O 2002 2011 The International Health Terminology Standards Development Organisation Basic Components of SNOMED CT 17 Chapter 3 Basic Components of SNOMED CT Topics Concepts Descriptions Relationships
87. ionships Table it indicates that Concept is a subtype of Concepi2 See the Technical Reference Guide for more information about SNOMED CT tables 2002 2011 The International Health Terminology Standards Development Organisation 80 SNOMED CT User Guide January 2011 Subset Mechanism xtensions Core Tables References Subset Members Relationships History Mechanism m Derivatives Descriptions Indexes Cross Mapping Mechanism Cross Map Sets y Navigation Hierarchies Cross Maps Canonical Table Y Namespace Identifier Cross Map Targets Word Equivalents Duplicate Terms BOO Figure 13 SNOMED CT Data Structure Summary 6 3 History 6 3 1 Component History Introduction The content of SVOMED CT evolves with each release The types of changes made include new Concepts new Descriptions new Relationships between Concepts new Cross Maps and new Subsets as well as updates and retirement of any of these Components Drivers of these changes include changes in understanding of health and disease processes introduction of new drugs investigations therapies and procedures and new threats to health as well as proposals and work provided by SNOMED users 6 3 2 History Mechanism The history mechanism involves the following tables e Component History Tabl
88. ired body structure 442083009 ProceQuro om Colom procedure lt lt PROCEDURE SITE colon structure body structure Procedures need not necessarily be categorized by site Human body structure should not be assigned as a default value of this attribute because many procedures can be performed on non human subjects and because this attribute does not necessarily need to be present in a procedure concept definition in order for classifier algorithms to work properly The general PROCEDURE SITE attribute is used to model the site for high level grouper type procedure concepts lt is most likely to be used for concepts that do not require a METHOD action attribute Relatively few concepts will be modeled using PROCEDURE SITE rather than the more specific direct and indirect site attributes see below S 4 4 1 1 PROCEDURE SITE DIRECT This attribute is used when the action of the procedure is directly aimed at an anatomical or acquired body structure or site rather than at something else such as a device located there 2002 2011 The International Health Terminology Standards Development Organisation 40 SNOMED CT User Guide January 2011 Table 23 Permissible values for PROCEDURE SITE DIRECT Attribute Values Anatomical or acquired body structure 442083009 Ambulatorio oe pre segura lt lt METHOD Amputation action qualifier value Procedure site Direct Foot structure body
89. ired to be unique Relationships Relationships link concepts in SNOMED CT There are four types of relationships that can be assigned to concepts in SNOMED CT e Defining e Qualifying e Historical Additional The relationships addressed in this section are known as defining relationships which are used to model concepts and create their logical definitions 3 3 1 Relationships and concept definitions Each concept in SNOMED CT is logically defined through its relationships to other concepts Every active SNOMED CT concept except the SNOMED CT Concept Root concept has at least one is a relationship to a supertype concept is a relationships and defining attribute relationships are known as the defining characteristics of SNOMED CT concepts They are considered defining because they are used to logically represent a concept by establishing its relationships with other concepts This is accomplished by establishing Is a relationships with one or more defining concepts called supertypes and modeling the difference with those supertypes through defining attributes us Example Fracture of tarsal bone disorder is defined as e is a subtype of Fracture of foot disorder e and has finding site Bone structure of tarsus body structure 2002 2011 The International Health Terminology Standards Development Organisation 22 SNOMED CT User Guide January 2011 e andhas associated morpholog
90. lude the surgical approach e g translumbar equipment e g sutures or physical forces e g laser energy Table 28 Permissible values for METHOD Attribute Values Action 129264002 lt lt Incision of ureter procedure e METHOD Incision action qualifier value Procedure site Direct Ureteric structure body structure The METHOD can be considered the anchor of each relationship group that defines a procedure if there are two methods there should be two different relationship groups It is correct to regard each relationship group as a kind of sub procedure that defines the overall procedure Each method can be regarded as the verb of a sentence and the verbs direct and indirect objects are specified by the site morphology device substance or energy attributes below that are grouped with it S 4 4 4 PROCEDURE DEVICE PROCEDURE DEVICE is a general attribute used to model devices associated with a procedure It subsumes the more specific attributes DIRECT DEVICE INDIRECT DEVICE USING DEVICE and USING ACCESS DEVICE which should be used instead of PROCEDURE DEVICE if possible The general attribute PROCEDURE DEVICE is mainly useful for defining high level general concepts that aggregate procedures according to the device involved Table 29 Permissible values for PROCEDURE DEVICE Attribute Values Catheter procedure procedure Device 49062001 lt lt P
91. lung e isa pneumonia e pathological process infectious process e associated morphology inflammation e associated morphology consolidation e finding site lung structure Figure 5 Definition of Infective pneumonia disorder e l isa bacterial lower respiratory infection e isal infective pneumonia e causative agent bacteria e pathological process infectious process e associated morphology inflammation e associated morphology consolidation e finding site lung structure Figure 6 Definition of Bacterial pneumonia disorder Figure 7 Illustration of Defining Relationships on page 24 illustrates some of these Relationships graphically is a Relationships relate a concept to more general concepts of the same type In contrast Attribute Relationships such as Finding site and Causative agent relate a concept to relevant values in other branches of the subtype hierarchy 2002 2011 The International Health Terminology Standards Development Organisation 24 SNOMED CT User Guide January 2011 SNOMED CT Concept l sa Clinical Finding Finding site Infective neumonia Isa Bacterial pneumonia Figure 7 Illustration of Defining Relationships 2002 2011 The International Health Terminology Standards Development Organisation Chapter 4 Attribute
92. ms Examples of Assessment scales assessment scale concepts Glasgow coma scale assessment scale Stanford Binet intelligence scale assessment scale Examples of Tumor staging tumor staging concepts International Federation of Gynecology and Obstetrics FIGO staging system of gynecological malignancy tumor staging Dukes staging system tumor staging 5 17 Qualifier value The Qualifier value hierarchy contains some of the concepts used as values for SNOMED CT attributes that are not contained elsewhere in SNOMED CT Such a code may be used as the value of an attribute in a defining Relationship in pre coordinated definitions and or as the value of an attribute in a qualifier in a post coordinated expression However the values for attributes are not limited to this hierarchy and are also found in hierarchies other than Qualifier value For example the value for the attribute LATERALITY in the concept shown below is taken from the Qualifier value hierarchy Left kidney structure LATERALITY Left However the value for the attribute FINDING SITE in the concept shown below is taken from the Body structure hierarchy not the Qualifier value hierarchy Pneumonia FINDING SITE Lung structure Examples of Qualifier value concepts Unilateral e Left Puncture action S 5 18 Special concept The Top Level Conc
93. ms from provider observed signs Granted this permits inclusion of epistemology loaded terms cf Bodenreider el al FOIS 2004 but health care is full of such terms and they are or at least can be understandable reproducible and useful 4 4 Attributes used to define Procedure concepts Table 21 Approved Procedure attributes summary Defining Attribute Subsumed Attribute Allowable Values PROCEDURE SITE Anatomical or acquired body structure 442083009 lt lt Procedure site Direct Anatomical or acquired body structure 442083009 lt lt Procedure site Indirect Anatomical or acquired body structure 442083009 PROCEDURE Morphologically abnormal structure 49755003 lt lt MORPHOLOGY Direct morphology Morphologically abnormal structure 49755003 lt lt Indirect morphology Morphologically abnormal structure 49755003 lt lt METHOD Action 129264002 lt lt 2002 2011 The International Health Terminology Standards Development Organisation 38 SNOMED CT User Guide January 2011 Defining Attribute Subsumed Attribute Allowable Values PROCEDURE DEVICE Device 49062001 lt lt DIRECT DEVICE Device 49062001 lt lt INDIRECT DEVICE Device 49062001 lt lt USING DEVICE Device 49062001 lt lt USING ACCESS Device 49062001 lt lt DEVICE ACCESS Surgical access values 309795001 lt lt Q DIRECT SUBSTANCE Substance 105
94. ncer for example is generally not subclassed according to mild moderate and severe types but rather is subclassed according to stage or grade For these reasons the SEVERITY attribute cannot be relied on to retrieve all Clinical findings with serious or life threatening import Nevertheless it is still useful for subclassing certain concepts and differentiating between different severities of a single disorder SEVERITY is not used to model any concepts pre coordinated in the International Release but it can still be used in post coordination as a qualifier Table 11 Permissible values for SEVERITY 4 3 8 CLINICAL COURSE This attribute is used to represent both the course and onset of a disease Many conditions with an acute sudden onset also have an acute short duration course Few diseases with a chronic long term course would need to have their onset sub divided into rapid or gradual subtypes and thus there is no clear need for separating the rapidity of onset from the duration of a disease based on testing by implementers and modelers a single attribute with values that combine these meanings has clearly been more reproducible and useful than two attributes that attempt to separate the meanings Table 12 Permissible values for CLINICAL COURSE Attribute Values Acute amebic dysentery disorder CLINICAL COURSE Sudden onset AND OR short duration qualifier value Courses 288524001 lt lt Q Chro
95. ng procedures that use devices e g catheterization Examples of Physical object concepts e Military vehicle physical object Implant device physical object e Artificial kidney device physical object e Latex rubber gloves physical object Book physical object e Pressure support ventilator physical object Vena cava filter physical object 5 12 Physical force The concepts in the Physical force hierarchy are directed primarily at representing physical forces that can play a role as mechanisms of injury Examples of Physical force concepts Spontaneous combustion physical force Alternating current physical force e Friction physical force S 5 13 Event The Event hierarchy includes concepts that represent occurrences excluding procedures and interventions Examples of Event concepts Flood event 2002 2011 The International Health Terminology Standards Development Organisation 72 SNOMED CT User Guide January 2011 Bioterrorist attack event Earthquake event 5 14 Environments and geographic locations The Environment or geographical location hierarchy includes types of environments as well as named locations such as countries states and regions Examples of Environments and geographic locations concepts The Social context hierarchy contains social conditions an
96. nic fibrosing pancreatitis disorder CLINICAL COURSE Chronic qualifier value The word acute has more than one meaning and the meanings are often overlapping or unclear The word acute may imply rapid onset short duration or high severity in some circumstances it might be used to mean all of these For morphological terms it may also imply the kind of morphology associated with the speed of onset Acute inflammation morphologic abnormaility does not necessarily have CLINICAL COURSE Sudden onset AND OR short duration but rather implies polymorphonuclear infiltration likewise Chronic 2002 2011 The International Health Terminology Standards Development Organisation 34 SNOMED CT User Guide January 2011 inflammation morphologic abnormality implies mononuclear cell infiltration not necessarily a chronic course although inflammation with a chronic course is highly correlated with a lymphocytic infiltration S 4 3 9 EPISODICITY EPISODICITY is used to represent episodes of care provided by a physician or other care provider typically a general practitioner not episodes of disease experienced by the patient See EPISODICITY no longer modeled in active content on page 85 regarding the origin of the attribute For example asthma with EPISODICITY first episode represents the first time the patient presents to their health care provider with asthma EPISODICITY is not used to model any concepts pre coordinat
97. nnncnnnnn nan nnnc cc cnn nnnnn cnn 51 SPECIMEN PROCEDURE riidoistaan aiaa aaea apaa e aa aa iaa addaa iea aeaa 51 SPECIMEN SOURCE TOPOGRAPHY ccccccceeceeeeeeeeeeeeeeseeeeeeeaeeseeeeeesaaeeeeneeess 52 SPECIMEN SOURCE MORPHOLOG Y iiccccnccccnconcnonaccnnnnncnnnnnnncnnnnnnnnnn cnn n na iaie 52 SPECIMEN SUBS AN O E a eaa aa Ae nn n anne cnn a E A aaa 53 SPECIMEN SOURCE IDENTITY 0 c cceeececeeeeeeeeeeeeceaeeeeeeeeeseaeeeesaaeeseeeeeesaaeeeeneeess 53 2002 2011 The International Health Terminology Standards Development Organisation 4 SNOMED CT User Guide January 2011 Attributes used to define Body structure CONCEPTS ooonocccccnnnnoccconnnoccnccnnnnnnnc cnn nrrrccnnannnncnn 53 EATERAL iu a Qe 54 Attributes used to define Pharmaceutical Biologic Product Concepts ccceeeeeeeeeeenees 54 HAS ACTIVE INGREDIENT cc cccceeeeeseneeeceeeeeeeaeeeceaeeeeeaaeeseeeeeesaaeeeeeeeeessaeeeseaeeesaas 54 HAS DOSE FOR Misa A ene oasa 55 Attributes used to define Situation with Explicit Context CONCEPTS oocoocccconnnccinccccononnnnnnnccnnnos 55 A A a oo co 56 Default Context sites a A TO 56 NA O ia ect S 56 Overview of Context attributes oooonnninnnnicnnnccnnnnnnconcccnnnrnnnnnoccnnnrnn naar nc cnn cnn rca 56 ASSOCIATED ANDIN G a aaa as aaraa ane laten 57 FINDING GCONTE AE E A EE E E AE 57 ASSOCIATED PROCEDURE pidii ioii aaaea iiiaae dara ia ea neadan diia 58 PROCEDURE CONTEXT oine iiaa a aaa ai a aae aaa A a n 58 T
98. nology Standards Development Organisation 1 7 Preface 11 e Technical Implementation Guide Namespace Identifier Guide e Namespace Identifier Registry File Naming Convention Stated Relationships Guide Developer Toolkit Guide e Canonical Table Guide e RF2 Data Structures Specification e RF2 Reference Set Specifications e RF2 Update Guide Document History Version Notes January 2006 July 2006 January 2007 Modified guide organization and structure Updated descriptions and examples for SNOMED CT attributes and hierarchies Added overview of SNOMED CT structure and technology considerations Revised glossary Added section on the use of attributes for Event hierarchy Updated Attributes used to define Clinical findings modifications were made to use of SEVERITY EPISODICITY and PATHOLOGICAL PROCESS Renamed Context dependent category context dependent category hierarchy to Situation with explicit context situation Updated Attributes used to define Procedure concepts added ROUTE OF ADMINISTRATION as an attribute Update to Attributes used to define Clinical findings COURSE and ONSET were retired CLINICAL COURSE was introduced Update to Attributes used to define Procedure concepts e Retired USING and ACCESS INSTRUMENT and replaced with USING DEVICE and USING ACCESS DEVICE e Changes to ACCESS attribute New attributes USING SUBSTANCE and USING ENERGY New range for LATERALITY attribut
99. nown as Clinical Terms Version 3 formerly known as Read Codes Version 3 which was created on behalf of the UK Department of Health and is Crown copyright This document forms part of the International Release of SNOMED CT distributed by the International Health Terminology Standards Development Organisation IHTSDO and is subject to the IHTSDO s SNOMED CT Affiliate Licence Details of the SNOMED CT Affiliate Licence may be found at www ihtsdo org our standards licensing 2002 2011 The International Health Terminology Standards Development Organisation 14 SNOMED CT User Guide January 2011 No part of this document may be reproduced or transmitted in any form or by any means or stored in any kind of retrieval system except by an Affiliate of the IHTSDO in accordance with the SNOMED CT Affiliate Licence Any modification of this document including without limitation the removal or modification of this notice is prohibited without the express written permission of the IHTSDO Any copy of this document that is not obtained directly from the IHTSDO or a Member of the IHTSDO is not controlled by the IHTSDO and may have been modified and may be out of date Any recipient of this document who has received it by other means is encouraged to obtain a copy directly from the IHTSDO or a Member of the IHTSDO Details of the Members of the IHTSDO may be found at www ihtsdo org members 2002 2011 The International Health Terminology Stand
100. ns and procedures that have not yet occurred e g Endoscopy arranged situation e Conditions and procedures that refer to someone other than the patient e g Family history Diabetes mellitus situation Discussed with next of kin situation e Conditions and procedures that have occurred at some time prior to the time of the current entry in the record e g History of aortic aneurysm situation History of solenectomy situation In each of these examples clinical context is specified The second example in which someone other than the patient is the focus of the concept could be represented in an application or record structure by combining a header term Family history with the value Diabetes The specific context in this case family history would be represented using the record structure In this case the pre coordinated context dependent concept Family history Diabetes mellitus situation would not be used because the information model has already captured the family history aspect of the diabetes Concepts in the Procedure and Clinical finding hierarchy have a default context of the following e The procedure has actually occurred versus being planned or canceled or the finding is actually present versus being ruled out or considered e The procedure or finding being recorded refers to the patient of record versus for example a family member The procedure or finding is occurring n
101. ntains terms from the British Association of Dermatology BAD and is used by permission of BAD Crown Copyright 2003 British Association of Dermatologists This work contains terms from The Royal College of Anaesthetists RCoA and is used by permission of RCOA Crown Copyright 2003 The Royal College of Anaesthetists This work contains terms from the Authorized Osteopathic Thesaurus and is used by permission of the American Association of Colleges of Osteopathic Medicine and the American Osteopathic Association 2002 2011 The International Health Terminology Standards Development Organisation
102. nym Infarction of heart Descriptionld 37441018 Each of the above descriptions has a unique Descriptionld and all of these descriptions are associated with a single Concept and the single Conceptld 22298006 S 3 2 1 Types of descriptions 3 2 1 1 Fully Specified Name Each concept has one Fully Specified Name FSN intended to provide an unambiguous way to name a concept The purpose of the FSN is to uniquely describe a concept and clarify its meaning The FSN is not a commonly used term or natural phrase and would not be expected to appear in the human readable representation of a clinical record ug Note The term in each FSN is unique across the entire active content of a SNOMED CT Release Each FSN term ends with a semantic tag in parentheses The semantic tag indicates the semantic category to which the concept belongs e g clinical finding disorder procedure organism person etc The semantic tag helps to disambiguate the different concept which may be referred to by the same commonly used word or phrase gg Example Hematoma morphologic abnormality is the FSN of the concept that represents the hematoma that a pathologist sees at the tissue level In contrast Hematoma disorder is the FSN of the conceptthat represents the clinical diagnosis that a clinician makes when they decide that a person has a hematoma 3 2 1 2 Preferred Term Each concept has one Preferred Term in a given language
103. ode from Clinical finding or Procedure to Situation with explicit context The resulting modified meaning is not a subtype of the original meaning of the code and therefore the axis modifying attributes are not used to qualify the code but instead are used to qualify a situation code For instance if Fine needle biopsy procedure is given the non context modifying attribute Procedure site Direct and a value of Urinary bladder structure body structure the resulting concept Fine needle biopsy of urinary bladder procedure is still a subtype of the original concept Fine needle biopsy procedure However the concept Urine protein test not done situation uses the context modifying attribute PROCEDURE CONTEXT and a value of Not done qualifier value and the resulting conceptis not a subtype of Urine protein test procedure Its axis hierarchy has been modified S 4 9 4 Overview of context attributes Of the six attributes applied to concepts in the Situation with explicit context hierarchy two are used only in representing the context in which a Clinical finding is recorded ASSOCIATED FINDING and FINDING CONTEXT two are used only in representing the context in which a Procedure is recorded ASSOCIATED PROCEDURE and PROCEDURE CONTEXT and two attributes are used in representing the context of both Procedure and Clinical finding SUBJECT RELATIONSHIP CONTEXT and
104. odes were inherited from CTV3 and were used to facilitate mapping to ICD 10 They have all been retired by moving them to the UK NHS extension and are not recommended for use in clinical records Explanations of these term prefixes are as follows Table 74 Term Preface Symbols Terms starting with X were initially used in the Read codes in the 1995 release in order to identify ICD 10 terms that were not present in ICD 9 Terms starting with D are also from CTV3 and identify terms contained in ICD 9 Chapter XVI Symptoms signs and ill defined conditions and ICD 10 Chapter XVIII Symptoms signs and abnormal clinical and laboratory findings not elsewhere classified The D meant that in CTV3the code was intended for use in a diagnosis field in the record even though the term meaning is not a kind of disease A term starting with V identifies concept codes derived from ICD 9 Supplementary classification of factors influencing health status and contact with health services V codes and ICD 10 Chapter XXI Factors influencing health status and contact with health services Z codes A term starting with M identifies Morphology of Neoplasm terms present in CD9 and ICD 10 A term starting with SO signifies that the term was contained in OPCS 4 Office of Population Censuses and Surveys Classification of Surgical Operations and Procedures 4th Revision Chapter Z subsidiary classification of sites of o
105. organism include but are not limited to Animal organism Microorganism organism Kingdom Plantae organism Examples of Organism concepts Streptococcus pyogenes organism Texon cattle breed organism e Bacillus anthracis organism e Lichen plant organism 2002 2011 The International Health Terminology Standards Development Organisation Hierarchies 67 5 8 Substance The Substance hierarchy contains concepts that can be used for recording active chemical constituents of drug products food and chemical allergens adverse reactions toxicity or poisoning information and physicians and nursing orders Concepts from this hierarchy represent general substances and chemical constituents of Pharmaceutical biologic product product which are in a separate hierarchy However sub hierarchies of Substance also include but are not limited to Body substance substance concepts to represent body substances Dietary substance substance Diagnostic substance substance Examples of Substance concepts e Insulin substance Methane substance Chromatin substance Dental porcelain material substance Albumin substance Endorphin substance e Acetaminophen substance S 59 Pharmaceutical biologic product The Pharmaceutical biologic product hierarchy is separate from the Substance h
106. ow or at a specified time versus some time in the past In addition to using the record structure to represent context there is sometimes a need to override these defaults and specify a particular context using the formal logic of the terminology For that reason SNOMED CT has developed a context model to allow users and or implementers to specify context using the terminology without depending on a particular record structure The Situation with explicit context hierarchy and various attributes assigned to concepts in this hierarchy accomplish this Examples of Situation with explicit context concepts e Family history Myocardial infarction situation No family history of stroke situation e Nasal discharge present situation Suspected epilepsy situation 2002 2011 The International Health Terminology Standards Development Organisation 66 SNOMED CT User Guide January 2011 5 5 Observable entity Concepts in this hierarchy can be thought of as representing a question or procedure which can produce an answer or a result For instance Left ventricular end diastolic pressure observable entity could be interpreted as the question What is the left ventricular end diastolic pressure or What is the measured left ventricular end diastolic pressure Observables are entities that could be used to code elements on a checklist or any element where a value can be assigned Color of na
107. peration in CTV3 A term starting with Q identifies temporary qualifying terms inherited from CTV3 amp 8 2 Negation The meaning of some concept codes in SNOMED CT depends conceptually on negation e g absence of X lack of X unable to do X etc 2002 2011 The International Health Terminology Standards Development Organisation Miscellaneous Topics 89 G 8 2 1 Negation and Context The Situation with explicit context hierarchy is intended to manage this kind of semantic situation The concept model allows a concept code in the Situation with explicit context hierarchy to be related to the Clinical finding about which context is asserted For example Absence of nausea and vomiting situation lis modeled as a Situation with explicit context in which the finding of Nausea and vomiting disorder is absent The inclusion of negated meanings introduces complications into query formulation machine classification and reasoning tasks The inclusion of a NOT logical operator into the SNOMED CT compositional model could simplify modeling of negated meanings The current release of SNOMED CT does not directly support classification using this operator but some modeling formalisms in current use today including database formalisms Description Logic formalisms include a NOT operator as a fundamental modeling primitive G 8 2 2 Known Problems with Negation There is still work to be done in moving all approp
108. ps to add clarity to concept definitions A Relationship group combines an attribute value pair with one or more other attribute value pairs Relationship groups originated to add clarity to Clinical finding concepts which require multiple ASSOCIATED MORPHOLOGY attributes and multiple FINDING SITE attributes and to Procedure which require multiple METHOD attributes and multiple PROCEDURE SITE attributes However Relationship groups are not limited to Clinical finding and Procedure concepts In the case of Procedure Relationship groups generally associate the correct method with the correct site In the example below the Relationship groups clarify that there is exploration of the bile duct and excision of the gall bladder Without Relationship groups the four attributes would be ungrouped and it would be unclear whether the excision was of the bile duct or of the gall bladder 2002 2011 The International Health Terminology Standards Development Organisation 62 SNOMED CT User Guide January 2011 Cholecystectomy and exploration of the bile duct Exploration PROCEDURE SITE DIRECT Bile duct structure Excision PROCEDURE SITE DIRECT Gall bladder structure Figure 9 Example Cholecystectomy and exploration of bile duct 2002 2011 The International Health Terminology Standards Development Organisation Chapter 9 Hierarchies 63 Hierarchies
109. r entities are not strictly body structures but are in the body structure hierarchy under morphologically abnormal structure and are valid values for the PROCEDURE MORPHOLOGY attributes 4 4 2 1 DIRECT MORPHOLOGY This attribute describes the morphologically abnormal structure that is the direct object of the METHOD action Table 26 Permissible values for DIRECT MORPHOLOGY Attribute Values Morphologically abnormal structure 49755003 lt lt Excision of benign neoplasm procedure METHOD Excision action qualifier value DIRECT MORPHOLOGY Neoplasm benign morphologic abnormality 2002 2011 The International Health Terminology Standards Development Organisation 42 SNOMED CT User Guide January 2011 S 4 4 2 2 INDIRECT MORPHOLOGY This attribute represents a morphology that is acted upon but is not the direct target of the action being performed i e the procedure s method acts directly on something else such as a device substance or anatomical structure Table 27 Permissible values for INDIRECT MORPHOLOGY Attribute Values Removal of mesh from wound procedure Morphologically abnormal structure 49755003 lt lt METHOD Removal action qualifier value DIRECT DEVICE Mesh physical object INDIRECT MORPHOLOGY Wound morphologic abnormality 4 4 3 METHOD This attribute represents the action being performed to accomplish the procedure It does not inc
110. ral glossary entries and aligned them to be identical with Technical Reference Guide glossary entries Expanded scope of User Guide to include new editorial policies that are currently being implemented in the International Release but with which the terminology may not yet be fully compliant Improved formatting and layout of the DITA generated document Updated information about the metadata hierarchy and related changes that will support implementation of the RF2 release format Incorporated formatting changes and example changes resulting from integrating the work on the Technical Implementation Guide Removed outdated historical sections from the appendix regarding the original merger of SNOMED and the Read Codes and content development processes for current information about quality processes and content development procedures users should refer to updated materials from the various IHTSDO Committees Added status icons to indicate status of individual sections Added section numbering In addition to pdf document the guide is released in html and help format Copyright Notice 2002 2011 The International Health Terminology Standards Development Organisation IHTSDO All Rights Reserved SNOMED CTO was originally created by The College of American Pathologists SNOMED and SNOMED CT are registered trademarks of the IHTSDO SNOMED CT has been created by combining SNOMED RT and a computer based nomenclature and classification k
111. rd to administrative groupings or classifications such as DRGs or ICD10 A system designed to support design and or implementation of messages that convey specified information using a specified set of SNOMED CT concept identifiers The SNOMED CT Technical Implementation Guide TIG provides information and guidance for software professionals responsible for designing developing and implementing SNOMED CT enabled software applications The TIG describes the technical requirements and design issues for integrating SNOMED CT into new and existing applications 2002 2011 The International Health Terminology Standards Development Organisation 84 SNOMED CT User Guide January 2011 Chapter l Changes and historical notes Topics 5 e EPISODICITY no longer modeled in active content ONSET and COURSE retired Dose form values moved Renaming the context situation hierarchy e Domain change for measurement evaluation attributes Move of findings to events O 2002 2011 The International Health Terminology Standards Development Organisation Changes and historical notes 85 G 7 1 EPISODICITY no longer modeled in active content EPISODICITY originated in the National Health Service Clinical Terms Version 3 where it was used not to specify the first episode of a disease for a patient but rather the first time a patient presented to their general practitioner GP for a particular disorder A first episode
112. riate concept codes to the Situation with explicit context hierarchy In particular many negated meanings are still represented by concept codes that are under a Clinical finding parent In the July 2008 release a significant number of subtypes of Functional finding finding were changed from primitive to sufficiently defined Sufficiently defining some concept codes in this subhierarchy e g Unable to stand finding and Does not retract tongue finding resulted in incorrect subsumption related to negation For example Does not retract tongue finding autoclassifies as a subtype of Does not move tongue finding with correct representation of negation the subtype relationship would be inverted so that Does not move tongue finding would imply Does not retract tongue finding While this negated content ultimately needs to be moved to the Situation with explicit context hierarchy the incorrect direction of subsumption relations for negated meanings also occurs in the Situation with explicit context hierarchy This is a limitation of the classifier currently being used rather than a fundamental limitation of the concept model The classifier will currently place concept codes in the wrong subsumption relationship when they are negated As another example it will infer that Adnexal tenderness absent situation Is a Tenderness absent situation This is an incorrect direction of subsumption
113. ription Relationship Subset etc The SCTID includes an item identifier a check digit and a partition identifier Depending on the partition identifier is may also include a namespace identifier SNOMED CT identifier SCTID 9 25 International release International release to be defined SNOMED CT International release SNOMED CT International edition International edition 9 26 Language For purposes of SNOMED CT translations a language is a vocabulary and grammatical form that has been allocated an ISO639 1 language code See also dialect 9 27 Language subset SNOMED CT can be translated into virtually any human language or dialect These translations attach new language specific terms as descriptions of existing concept codes and may also use existing descriptions if translation is not necessary A language subset is a set of references to the descriptions that are members of a language edition of SNOMED CT Additionally data in the language subset specifies the DescriptionType of each description Fully Specified Name Preferred Term or Synonym 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 99 9 28 Mapping mechanism A set of data structures for representing cross links to other terminologies and classifications The Mapping Mechanism data structures are distributed as three tables e Cross Map Sets Table e Cross Maps Table Cross Map Targets Table
114. s disorder e ASSOCIATED MORPHOLOGY Inflammation morphologic abnormality 4 3 3 ASSOCIATED WITH This attribute asserts an interaction between two concepts beyond simple co occurrence in the patient ASSOCIATED WITH represents a clinically relevant association between concepts without either asserting or excluding a causal or sequential relationship between the two Table 7 Permissible values for ASSOCIATED WITH Attribute Values Clinical Finding 404684003 lt lt Procedure 71388002 lt lt Event 272379006 lt lt Organism 410607006 lt lt Substance 105590001 lt lt Physical object 260787004 lt lt Physical force 78621006 lt lt Pharmaceutical biologic product 373873005 lt lt Q only SNOMED CT Concept 138875005 ASSOCIATED WITH subsumes the following more specific attributes in what is called an attribute hierarchy explained in Attribute Hierarchies in SNOMED CT on page 27 e AFTER DUE TO CAUSATIVE AGENT 4 3 4 AFTER This attribute is used to model concepts in which a clinical finding occurs after another clinical finding or procedure Neither asserting nor excluding a causal relationship it instead emphasizes a sequence of events O 2002 2011 The International Health Terminology Standards Development Organisation 32 SNOMED CT User Guide January 2011 Table 8 Permissible values for AFTER Attribute Values Clinical Finding
115. s Used in SNOMED CT Attributes Used in SNOMED CT 25 Topics Introduction Attribute Hierarchies in SNOMED CT Attributes used to define Clinical Finding concepts Attributes used to define Procedure concepts Attributes used to define Evaluation Procedure concepts Attributes used to define Specimen concepts Attributes used to define Body structure concepts Attributes used to define Pharmaceutical Biologic Product concepts Attributes used to define Situation with Explicit Context concepts Attributes used to define Event concepts Attributes used to define Physical Object concepts Relationship Groups in SNOMED CT S This part of the Editorial Guide provides an overview of the defining attributes used by the SNOMED CT concept model Further details are provided in the chapters dedicated to each hierarchy 2002 2011 The International Health Terminology Standards Development Organisation 26 SNOMED CT User Guide January 2011 4 1 Introduction SNOMED CT currently uses over 50 defining attributes to model concept definitions Each SNOMED CT attribute can usually be applied to one hierarchy and for a few attributes to more than one hierarchy The hierarchy or hierarchies to which an attribute can be applied are referred to as the domain of the attribute Each attribute can be given a limited set of values this set of values is called the range of the attribute S 4 1 1 Domain Th
116. s sub hierarchy are used to construct relationships between two SNOMED CT concepts since they indicate the relationship type between those concepts Some attributes relationship types can be used to logically define a concept defining attributes This sub hierarchy also includes non defining attributes like those used to track historical relationships between concepts or attributes that may be useful to model concept definitions but which have not yet been used in modeling pre coordinated concepts in SNOMED CT Examples of Defining attributes 2002 2011 The International Health Terminology Standards Development Organisation 76 SNOMED CT User Guide January 2011 e lisa Concept model attribute e Laterality Procedure site Finding site e Associated morphology Examples of Non defining attributes e Concept history attribute REPLACED BY SAME AS Unapproved attribute e Relieved by Has assessment 2002 2011 The International Health Terminology Standards Development Organisation Structure and Technology Considerations 77 Chapter 6 Structure and Technology Considerations Topics Introduction SNOMED CT tables e History SNOMED CT Subsets e Cross Mappings Extensions SNOMED CT applications and services 2002 2011 The International Health Terminology Standards Development Organisation 78 SNOMED CT Us
117. s that could overlap with ASSOCIATED MORPHOLOGY Inflammatory processes result in inflammation by definition but these disorders should be defined using their morphology 4 3 13 HAS DEFINITIONAL MANIFESTATION This attribute links disorders to the manifestations observations that define them It can only be applied to disorders 2002 2011 The International Health Terminology Standards Development Organisation 36 SNOMED CT User Guide January 2011 Table 17 Permissible values for HAS DEFINITIONAL MANIFESTATION Attribute Values Seizure disorder disorder HAS DEFINITIONAL MANIFESTATION Seizure finding Clinical finding 404684003 lt lt Hypertensive disorder systemic arterial disorder HAS DEFINITIONAL MANIFESTATION Finding of increased blood pressure finding 4 3 14 OCCURRENCE This attribute refers to the specific period of life during which a condition first presents Multiple values of JOCCURRENCE for a single concept are not desirable and these will be addressed in a future release This does not mean the condition cannot persist beyond the period of life in which it first presents Table 18 Permissible values for OCCURRENCE Attribute Values Childhood phobic anxiety disorder disorder OCCURRENCE Childhood qualifier value Periods of life 282032007 lt 4 3 15 FINDING METHOD This attribute specifies the means by which a clinical finding was determined T
118. s to the method The direct object s of the action verb should be represented using at least one of the four direct object attributes depending on whether the direct object on which the method acts is a device DIRECT DEVICE anatomical structure Procedure site Direct morphologic abnormality DIRECT MORPHOLOGY or substance DIRECT SUBSTANCE When the type body structure device or substance of direct object is indeterminate the direct object attributes should not be used S 4 5 Attributes used to define Evaluation Procedure concepts Table 45 Approved Evaluation Procedure attributes summary Defining Attribute Allowable Values HAS SPECIMEN Specimen 123038009 lt lt Q COMPONENT Substance 105590001 lt lt Q Observable entity 363787002 lt lt Q Cell structure 4421005 lt lt Q Organism 410607006 lt lt Q TIME ASPECT Time frame 7389001 lt lt Q PROPERTY Property of measurement 118598001 lt lt Q 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 49 Defining Attribute Allowable Values ISCALE TYPE Quantitative 30766002 lt lt Qualitative 26716007 lt lt Ordinal value 117363000 lt lt Ordinal or quantitative value 117365007 lt lt Nominal value 117362005 lt lt Narrative value 117364006 lt lt Text value 117444
119. sent a situation in which a Clinical finding is known or unknown and if known whether it is present absent or uncertain possible and also to express the meaning that the finding is not actual but instead an anticipated or possible future finding Table 65 Permissible values for FINDING CONTEXT Attribute Values Finding context value 410514004 lt lt Q Wo goug situation ASSOCIATED FINDING Cough finding FINDING CONTEXT Known absent qualifier value 2002 2011 The International Health Terminology Standards Development Organisation 58 SNOMED CT User Guide January 2011 4 9 7 ASSOCIATED PROCEDURE This attribute links concepts in the Situation with explicit context hierarchy to concepts in the Procedure hierarchy for which there is additional specified context Table 66 Permissible values for ASSOCIATED PROCEDURE Attribute Values Procedure 71388002 lt lt Q Operative procedure planned situation Observable entity 363787002 lt Q only ASSOCIATED PROCEDURE Surgical procedure procedure S 4 9 8 PROCEDURE CONTEXT This attribute indicates the degree of completion or status of a Procedure as well as its various possible future states prior to its being initiated or completed Table 67 Permissible values for PROCEDURE CONTEXT Attribute Values Operative procedure planned situation e ASSOCIATED PROCEDURE Surgical procedure procedure
120. software tool used for exploring and searching terminology content A typical SNOMED CT browser can locate concepts and descriptions by identifiers and by searching the text of description terms Various views of located concepts may be displayed including the set of related descriptions the hierarchical relationships and other defining relationships SNOMED CT browser 9 4 Check digit The check digit is the final rightmost digit of the SNOMED CT Identifier SCTID lt can be used to check the validity of SCTIDs Clinical information systems can use the check digit to identify SNOMED CT codes that have been entered incorrectly typo errors etc It is calculated using the Verhoeff algorithm 2002 2011 The International Health Terminology Standards Development Organisation 94 SNOMED CT User Guide January 2011 9 5 Component Refers to any item identified by an SCTID in the main body of SNOMED CT or in an authorized Extension The partition identifier indicates the type of component referred to by that SCTID Each component is a uniquely identifiable instance of one of the following Concept Description Relationship Other components in Release Format 1 e Subset e Subset Member e Cross Map Set Cross Map Target SNOMED CT component 9 6 Concept A clinical idea to which a unique Conceptld has been assigned The term concept may also be used informally with the following meanings The concept identifier
121. ssue Extensions They enable unique SCT Ds to be issued by many organizations and allow each SCTID to be traced to an authorized originating organization Partition identifier Extension item identifier ee SCTID 999999990989121104 Namespace identifier Check digit Figure 14 SCTID for an Extension Component 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 91 Chapter 9 User Guide Glossary Topics Attribute e Attribute value pair e Browser e Check digit Component Concept Concept equivalence Conceptld Concepts table Core Core table Cross map e CTV3ID Description Descriptionld Descriptions table Dialect Enabled application Extension e Fully defined Fully specified name Hierarchy e History mechanism SNOMED CT Identifier International release Language Language subset Mapping mechanism Modeler Modeling Namespaceld Partitionld Postcoordinated expression Precoordinated expression Primitive e Qualifying characteristic 2002 2011 The International Health Terminology Standards Development Organisation 92 SNOMED CT User Guide January 2011 Realm Relationship Relationship type Relationshipld Relationships table Release Root concept Root metadata concept SNOMED SNOMED Clinical Terms e Sufficiently defined Subset e Synonym
122. structure Biopsy of femur procedure e METHOD Biopsy action qualifier value e Procedure site Direct Bone structure of femur body structure S 4 4 1 1 1 Multiple values for PROCEDURE SITE DIRECT When the METHOD action acts directly on a morphological abnormality more simply a lesion arising from or existing in the cells of the tissue in which it occurs e g a tumor including metastatic tumors granuloma polyp or cyst the attribute DIRECT MORPHOLOGY is used to model the morphological abnormality Most concept definitions where DIRECT MORPHOLOGY is used which also require a site in the definition will use Procedure site Direct Thus there can be more than one direct object of the METHOD for a concept For example the DIRECT MORPHOLOGY and the Procedure site Direct can both be direct objects of the METHOD An example of an exception to this rule would be removal of a calculus from the ureter In this case the calculus is the direct object but there is no procedure site that is that direct object since the ureter is an indirect object The most common concepts that have more than one direct object of the METHOD are Subtypes of Removal procedure where the object of the removal e g a neoplasm can be considered to be a part of the tissue at the anatomical site in which it occurs When a part of an anatomical structure however abnormal has been removed both the morphologic
123. t coordinated expression should also have a METHOD with a value of Surgical action qualifier value or one of its subtypes so that the resulting concept becomes a subtype of Surgical procedure procedure 4 1 3 Range The Range is the set of values allowed for each attribute For example the Range for ASSOCIATED MORPHOLOGY is Morphologically abnormal structure morphologic abnormality and its descendants and the Range for FINDING SITE is Anatomical or acquired body structure body structure and its descendants in the Body structure hierarchy 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 27 Domain FINDING SITE Range Relationship Pneumonia ConceptID1 Type ConceptID2 Lung structure Defining attribute v Pneumonia Lung structure FINDING SITE Figure 8 Example Pneumonia FINDING SITE Lung structure The Domain for the FINDING SITE attribute is the Clinical finding hierarchy In the above example the attribute FINDING SITE has the value Lung structure body structure Lung structure body structure is found in the Anatomical structure body structure subhierarchy which is in the allowed range for FINDING SITE Defining attributes in SNOMED CT are assigned to the hierarchies where retrieval of clinical data is most useful and relevant e g
124. t of pages relevant to a particular topic The Subset Mechanism may be used to derive tables that contain only part of SNOMED CT In some cases these derived tables may also be centrally distributed e g a release table containing only Descriptions for a particular International Edition A Subset is a value added feature of SNOMED CT Subsets provide important information for the use and implementation of SNOMED CT The fact that a SNOMED CT Component belongs to a particular subset provides information above and beyond the Component itself SNOMED CT is a large terminology and subsets can define portions of the terminology for use by specific audiences For example a UK dialect subset for English may direct the user to descriptions for UK terms rather than all descriptions for English Subsets may also be used to specify simplified or shortened hierarchies for browsing sometimes called navigation hierarchies Note that it is up to the implementer to determine if a subset is used dynamically or statically and whether the subset contents are given precedence or used exclusively Refer to the SNOMED CT Technical Implementation Guide for more information Note that Subsets are not necessarily mutually exclusive The contents of Subsets may overlap 6 4 2 Subset table and file structures Acommon file structure is used for all Subsets This approach simplifies the release structure and installation process for all SNOMED users Subsets
125. tematized Nomenclature of Veterinary Medicine copyright 1982 1993 American Veterinary Medical Association Used with permission LOINC the Logical Observation Identifier Names and Codes copyright 1995 2008 Regenstrief Institute LOINC Committee All rights reserved NANDA North American Nursing Diagnosis Association Taxonomy II copyright 2005 2008 NANDA International All rights reserved The Perioperative Nursing Data Set PNDS copyright 2002 AORN Inc All rights reserved The Omaha System copyright 1992 Martin and Associates Used with permission The Clinical Care Classification copyright 2004 V K Saba Used with permission The Nursing Interventions Classification NIC copyright 2004 Mosby Inc and the Center for Nursing Classification and Clinical Effectiveness at the University of lowa College of Nursing Used with permission The Nursing Outcomes Classification NOC copyright 2004 Mosby Inc and the Center for Nursing Classification and Clinical Effectiveness at the University of lowa College of Nursing Used with permission This work contains material from the AJCC Cancer Staging Manual Sixth Edition 2002 published by Springer Verlag New York Used with permission of the American Joint Committee on Cancer AJCC Chicago Illinois The Anesthesia Patient Safety Foundation s APSF Data Dictionary Task Force Some material contributed Copyright 2003 APSF Inc Used by permission of the APSF This work co
126. the SNOMED CT release in which a component was added or changed SNOMED CT release Release version SNOMED CT edition ReleaseVersion 9 43 Root concept The single concept that is at the top of the SNOMED CT Concept hierarchy 2002 2011 The International Health Terminology Standards Development Organisation User Guide Glossary 103 9 44 Root metadata concept The single concept that is at the top of the SNOMED CT Model Component metadata hierarchy ue Note Most of the data in the metadata hierarchy is only relevant to Release Format 2 Therefore this concept may not be present in some Release Format 1 files Root metadata code 9 45 SNOMED An acronym for the SystematizedNomenclature of Medicine originally developed by the College of American Pathologists and now owned and maintained by the HTSDO SNOMED Clinical Terms is the most recent version of this terminology It was preceded by SNOMED RT and SNOMED International 9 46 SNOMED Clinical Terms SNOMED CT is a clinical terminology maintained and distributed by the HTSDO It is considered to be the most comprehensive multilingual healthcare terminology in the world It was created as a result of the merger of SVOMED RT and NHS Clinical Terms Version 3 SNOMED CT 9 47 Sufficiently defined A concept is sufficiently defined if its logic definition is sufficient to computably recognize automatically subsume all its subtypes The logic definition must also
127. ure SURGICAL APPROACH Abdominal approach qualifier value 4 4 14 USING SUBSTANCE This attribute describes the Substance used to execute the action of a procedure but it is not the substance on which the procedure s method directly acts the DIRECT SUBSTANCE Table 43 Permissible values for USING SUBSTANCE Attribute Values ISubstance 105590001 lt lt Contrast radiography of esophagus procedure METHOD Radiographic imaging action qualifier value Procedure site Direct Esophageal structure body structure USING SUBSTANCE Contrast media substance 2002 2011 The International Health Terminology Standards Development Organisation 48 SNOMED CT User Guide January 2011 4 4 15 USING ENERGY This attribute describes the energy used to execute an action USING ENERGY has been introduced because the new attribute USING DEVICE is now used only to represent the instrument or equipment used to execute the action Unlike the attribute USING which it replaces USING DEVICE does not take values from the physical force hierarchy Table 44 Permissible values for USING ENERGY Attribute Values Gamma ray therapy procedure Physical force 78621006 lt lt USING ENERGY Gamma radiation physical force S 4 4 16 Direct and indirect objects Procedures that have a METHOD attribute can be described using an action verb that correspond
128. user 9 38 Relationship An association between two Concepts each identified by a Conceptla The nature of the association is indicated by a RelationshipType Each Relationship is represented by a row in the Relationships Table 2002 2011 The International Health Terminology Standards Development Organisation 102 SNOMED CT User Guide January 2011 SNOMED CT relationship 9 39 Relationship type The nature of a Relationship between two Concepts Relationship Types are represented in SNOMED CT by Concept codes In the Relationships Table the RelationshipType field contains the Conceptld for the concept in SNOMED CT that forms the relationship between two other concepts Conceptld1 and Conceptld2 For defining and qualifying relationships the Relationship Type is an Attribute code Relationship Type should not be confused with Characteristic Type o Note Field name in SNOMED CT Release Format 1 9 40 Relationshipld A SNOMED CT Identifier that uniquely identifies a Relationship Relationshipld is the key of the Relationships Table Each row in the Relationships Table represents a relationship triplet Conceptld1 RelationshipType Conceptld2 maa Note Field name in SNOMED CT Release Format 1 9 41 Relationships table A data table consisting of rows each of which represents a Relationship ag Note Component Table name in SNOMED CT Release Format 1 9 42 Release A field in the Component History Table which indicates
129. y Fracture morphologic abnormality ie we Note A relationship is assigned only when that relationship is always known to be true ug Example Group A Streptococcus causes most cases of Streptococcal pharyngitis However a small percentage of these cases are caused by other species of Streptococcus Therefore it would be incorrect to define Streptococcal sore throat disorder as having causative agent Streptococcus pyogenes organism Instead it is correctly defined as having the more general causative agent Genus Streptococcus organism 3 3 2 IS A relationships is a relationships are also known as Supertype Subtype relationships or Parent Child relationships is a relationships are the basis of SNOMED CT s hierarchies as illustrated below Disorder of foot disorder Injury of foot disorder Fracture of foot disorder Open fracture of foot disorder Figure 2 Example IS A hierarchy A concept can have more than one is a relationship to other concepts In that case the concept will have parent concepts in more than one sub hierarchy of a top level hierarchy Subtype relationships can be multi hierarchical Disorder of foot Cellulitis Cellulitis of foot Figure 3 Example IS A relationships 2002 2011 The International Health Terminology Standards Development Organisation Basic Components of SNOMED CT 23 3 3 3 Attri
130. y physical force S 4 3 7 SEVERITY This attribute is used to subclass a Clinical finding concept according to its severity however caution is encouraged because this use is said to be relative By relative it is meant that it is incorrect to assume that the same degree of disease intensity or hazard is implied for all Clinical finding to which this attribute is applied There are three reasons 2002 2011 The International Health Terminology Standards Development Organisation Attributes Used in SNOMED CT 33 First severe could be interpreted differently depending on what other values are available to choose for severity Thus severity is relative to the other values in the value set presented to users Consider the different meaning of severity in each of the following three sets of values mild moderate severe minimal mild moderate severe very severe e mild mild to moderate moderate moderate to severe severe life threatening fatal Second the severity is defined relative to the expected degree of intensity or hazard of the Clinical finding that is being qualified Acommon cold has a baseline intensity or hazard much less than that of a more serious disease like lupus erythematosus or pneumonia thus a severe cold might be considered less intense or hazardous than a mild pneumonia Third some disorders that are life threatening do not ordinarily have a severity assigned to them Ca

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