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 conceptClassification concepts
    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 POSSIBLTPOSSIBLY_EQUIVALENT_To target concepts can sometimes be difficult.Share difficult ambiguous inactivations in the internal editor's meetings
    2. 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 meaning so 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
replacement concepts exist

Two possible meanings:

      

Concept
t

237055002

69878008 |Polycystic

ovary syndrome

ovaries (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

Example 1: Mixed ambiguity

  • Concept
    t200417002|Breast engorgement in pregnancy, the puerperium or lactation unspecified (finding)|
     has three possible meanings

Resolution:

  • Create 3 new concepts:
    • Concept
      txxxxxxxx|Breast engorgement in pregnancy (finding)|
    • Concept
      tyyyyyyyy|Breast engorgement in the puerperium (finding)|
    • Concept
      tzzzzzzzz|Breast engorgement during unspecified period of lactation (finding)|
  • Inactivate
    Concept
    t200417002|Breast engorgement in pregnancy, the puerperium or lactation unspecified (finding)|
    • POSSIBLY_EQUIVALENT_TO xxxxxxxx Breast engorgement in pregnancy (finding)
    • POSSIBLY_EQUIVALENT_TO yyyyyyyy Breast engorgement in the puerperium (finding)
    • POSSIBLY_EQUIVALENT_TO zzzzzzzz Breast engorgement during unspecified period of lactation (finding)
  • Now resolve the deprecated "unspecified" concept:
    • inactivate 
      Concept
      tzzzzzzzz|Breast engorgement during unspecified period of lactation (finding)|
       with reason for inactivation "Classification Concept"
      • REPLACED_BY 
        Concept
        t49746001|Engorgement of breasts (finding)|

Example 2: Mixed ambiguity with a conjunction:

  • Concept
    t199779004 |Persistent occipitoposterior or occipitoanterior position - delivered (disorder)|
     has 2 possible meanings, neither of which
exist in SNOMED CT
  • already existed in SNOMED CT at the time of writing, in 2021.

    The original meaning of this code dates back to ICD9: it is closely related to D660.3 DEEP TRANSVERSE ARREST AND PERSISTENT OCCIPITOPOSTERIOR POSITION DURING LABOR AND DELIVERY, a subtype within ICD9 of D660 OBSTRUCTED LABOR. This implicit meaning as a form of obstructed labor was also originally also reflected in SNOMED by its classification (back in 2002) as a subtype of 
    Concept
    t199746004|Obstructed labor (finding)|
    . From this archaeology, it becomes clearer that the "persistent" adjective in the term relates in fact only to the "occipitoposterior presentation" permutation; an occipitoanterior presentation of the fetal head is the normal state of affairs in labour, and so would not usually be labelled as "persistent". That labour was obstructed, whichever the presentation, is unstated within the original SNOMED and ICD terms but was implicit from the original taxonomy in both ICD and later also in SNOMED.

    This leads to the following two possible meanings:

    • POSSIBLY_EQUIVALENT_TO
xxxxxxxx Persistent
    • xxxxxxxx Obstructed labour despite occipitoanterior presentation and now delivered
    • POSSIBLY_EQUIVALENT_TO
yyyyyyyy Persistent occipitoposterior
    • yyyyyyyy Obstructed labour due to 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, it is
is
  • necessary to resolve the conjunction that arises from the original concept.

Resolution:

  • Create 2 new concepts:
    •  
      Concept
      txxxxxxxx
Persistent occipitoposterior
    • |Obstructed labour despite occipitoanterior presentation and now delivered (finding)|
    •  
      Concept
      tyyyyyyyy
Persistent occipitoanterior
    • |Obstructed labour due to persistent occipitoposterior presentation and now delivered
(finding)
    • |

  • Inactivate 

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

 as ambiguous
    • POSSIBLY_EQUIVALENT_TO
xxxxxxxx Persistent
    • xxxxxxxx Obstructed labour despite occipitoanterior presentation and now delivered (disorder)
    • POSSIBLY_EQUIVALENT_TO
yyyyyyyy Persistent occipitoposterior
    • yyyyyyyy Obstructed labour due to persistent occipitoposterior presentation and now delivered (disorder)
  • Now resolve the 2 conjunctions:
    • Inactivate 
      Concept
      txxxxxxxx
Persistent occipitoposterior
    • |Obstructed labour despite occipitoanterior presentation and now delivered (
disorder
    • finding)|
as
    •  as a Classification concept
      • PARTIALLY_EQUIVALENT_TO 
        Concept
        t199746004 |Obstructed labour (finding)|
      • PARTIALLY_EQUIVALENT_TO 
        Concept
        t
90381008
      • 37235006 |
Occipitoanterior
      • Occipitoposterior position (finding)|
      • PARTIALLY_EQUIVALENT_TO 
        Concept
        t236973005 |Delivery procedure (procedure)|
inactivate 
      • PARTIALLY_EQUIVALENT_TO 
        Concept
        t289256000|Mother delivered (finding)|
    • inactivate  
      Concept
      t
xxxxxxxx Persistent occipitoanterior
    • yyyyyyyy|Obstructed labour due to persistent occipitoposterior presentation and now delivered
(disorder)
    • |
      as a Classification concept
      • PARTIALLY_EQUIVALENT_TO 
        Concept
        t31041000119106|Obstructed labour due to deep transverse arrest and persistent occipitoposterior position|
      • PARTIALLY_
  • EQUIVALENT_TO
        • EQUIVALENT_TO 
          Concept
          t236973005 |Delivery procedure (procedure)|

    ...

        • PARTIALLY_EQUIVALENT_TO 
          Concept
          t289256000|Mother delivered (finding)|

    Resolving sequences of Historical Associations

    The intention is that this functionality to resolve sequences of Historical Associations will normally be seamlessly integrated into the tooling so as to present to the user the appropriate updated historically association to be allocated.

    Whenever an already stated POSSIBLY_EQUIVALENT_TO target itself also becomes inactive - whether at the same release or later , - identifying the new active, direct replacement(s) for the original inactive concept , should follow the combinatorial logic stated below.

    Combinatorial Logic

    (A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) SAME_AS (D) implies A POSSIBLY_EQUIVALENT_TO (C OR D)

    (A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) REPLACED_BY (D) implies (A) POSSIBLY_EQUIVALENT_TO (C OR D)

    (AIntEd) POSSIBLY_EQUIVALENT_TO (BIntEd OR CIntEd) and (BIntEd) MOVED_TO (DNRC) implies (AIntEdAIntEd) POSSIBLY_EQUIVALENT_TO (CIntEd)

    (A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) POSSIBLY_EQUIVALENT_TO (D OR E) implies A POSSIBLY_EQUIVALENT_TO (C OR D OR E)

    (A) POSSIBLY_EQUIVALENT_TO (B OR C) and (B) WAS_A (D AND E) implies ((A) POSSIBLY_EQUIVALENT_TO (C) OR (A) WAS_A (D AND E))

    ...