SNOMED CT Editorial Advisory Group

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Inactivation ReasonAssociation TypeDescription

Ambiguous

“POSSIBLY_EQUIVALENT_TO”

This inactivation reason explicitly states that the inactivated concept is inherently ambiguous but that each of the potential meanings represented by the ambiguous concept is semantically identical to one of the “POSSIBLY_EQUIVALENT_TO” target concepts, whether currently present or could be created in SNOMED CT.

The implication of this definition is that for any given ambiguous concept there must be 2 or more POSSIBLY_EQUIVALENT_TO target concepts.

Guidance
  • Identify all potential meanings represented in the ambiguous concept
    Identify ALL possible meanings that arise from the ambiguity. Identify semantically equivalent SCT concepts where they exist, and create new concepts where they do not exist.
  • Non or partial synonymous synonyms
    Resolve these by inactivation as "Not semantically equivalent component' and the association type of "REFERS_TO" reassigning the description to either an existing concept or if necessary creating a new concept.
  • Ensure that the synonyms on the inactive concept are represented within the appropriate active concept(s).
  • Classification concept
    If the concept's ambiguity results from a classification disjunction or conjunction, use the inactivation reason of "Classification concept".
  • Incorrect modeling
    Where the modeling of the concept is at variance with the meaning of the FSN, correct the modeling - this advice may change once the QI project has been completed and ECL is widely used.
  • Additional notes:
    1. Identifying true ambiguity rather than lack of specificity or the meaning is "not known" and resolving the full suite of POSSIBLT_EQUIVALENT_To target concepts can sometimes be difficult.
    2. Share difficult ambiguous inactivations in the internal editor's meetings
    3. It is possible that one of the interpretations of the ambiguity gives rise to a concept that is not clinically meaningful. It is still important to create a concept to represent this concept to ensure that there is full semantic equivalence between the sum of the POSSIBLY_EQUIVALENT_TO targets and the ambiguous concept being inactivated as this is the only way of supporting analysis of historically coded clinical data that may have used the ambiguous concept. As a secondary action, the concept that is not clinically meaningful may then itself be inactivated.

Examples

Inherently ambiguous FSN with multiple meanings

Multiple possible meanings:

  • Concept
    t269530002 |Ca lesser curvature - stomach (disorder)|
     has 3 possible meanings all of which exist within SNOMED CT:
  • Concept
    t254563009 |Carcinoma of lesser curve of stomach (disorder)|
  • Concept
    t269459004 |Malignant tumor of lesser curve of stomach (disorder)|
  • Concept
    t93867004 |Primary malignant neoplasm of lesser curvature of stomach (disorder)|

Resolution:

  • Inactivate 269530002 |Ca lesser curvature - stomach (disorder)| with the following target historical associations:
    • POSSIBLY_EQUIVALENT_TO 
      Concept
      t254563009 |Carcinoma of lesser curve of stomach (disorder)|
    • POSSIBLY_EQUIVALENT_TO 
      Concept
      t269459004 |Malignant tumor of lesser curve of stomach (disorder)|

    • POSSIBLY_EQUIVALENT_TO

      Concept
      t93867004 |Primary malignant neoplasm of lesser curvature of stomach (disorder)|


Inherently ambiguous FSN but not all reeplaceement concepts exist

Two possible meanings:

      

Concept
t237055002 |Polycystic ovary syndrome (disorder)|
 has 2 possible meanings one of which does not exist within SNOMED CT:

  • Polycystic ovary syndrome - available in SCT 
    Concept
    t237055002 |Polycystic ovary syndrome (disorder)|
  • Polycystic ovary - did not exist in SCT

Resolution:

  • Create a new concept: Polycystic ovary
  • Inactivate 69878008 |Polycystic ovaries (disorder)| with the following target historical associations:
    • POSSIBLY_EQUIVALENT_TO 
      Concept
      t781067001 |Polycystic ovary (disorder)|
    • POSSIBLY_EQUIVALENT_TO 
      Concept
      t237055002 |Polycystic ovary syndrome (disorder)|


Ambiguous concept that requires intermediate deprecated inactive concepts

Mixed ambiguity with conjunction:

  • Concept
    t199779004 |Persistent occipitoposterior or occipitoanterior position - delivered (disorder)|
     has 2 possible meanings, neither of which exist in SNOMED CT:
    • POSSIBLY_EQUIVALENT_TO xxxxxxxx Persistent occipitoanterior presentation and now delivered
    • POSSIBLY_EQUIVALENT_TO yyyyyyyy Persistent occipitoposterior presentation and now delivered
  • However, both of these are compound clinical statements that should not be added as active concepts but are required in order to satisfy the requirement to ensure clinically safe reporting of historical data.
  • In addition
is
  • , it is necessary to resolve the conjunction that arises from the original concept.

Resolution:

  • Create 2 new concepts:
    •  
      Concept
      txxxxxxxx Persistent occipitoposterior presentation and now delivered (finding)
    •  
      Concept
      tyyyyyyyy Persistent occipitoanterior presentation and now delivered (finding)

    • Inactivate 

      Concept
      t199779004 |Persistent occipitoposterior or occipitoanterior position - delivered (disorder)|
       as ambiguous

      • POSSIBLY_EQUIVALENT_TO xxxxxxxx Persistent occipitoanterior presentation and now delivered (disorder)
      • POSSIBLY_EQUIVALENT_TO yyyyyyyy Persistent occipitoposterior presentation and now delivered (disorder)
  • Now resolve the 2 conjunctions:
    • Inactivate 
      Concept
      txxxxxxxx Persistent occipitoposterior presentation and now delivered (disorder)
      as a Classification concept
      • EQUIVALENT_TO 
        Concept
        t37235006 |Occipitoposterior position (finding)|
      • EQUIVALENT_TO 
        Concept
        t236973005 |Delivery procedure (procedure)|
    • inactivate 
      Concept
      txxxxxxxx Persistent occipitoanterior presentation and now delivered (disorder)
       as a Classification concept
      • EQUIVALENT_TO
        Concept
        t90381008 |Occipitoanterior position (finding)|
      • EQUIVALENT_TO 
        Concept
        t236973005 |Delivery procedure (procedure)|

Managing Incoming Historical Associations

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