Purpose

The main reasons for adding descriptions in an extension are:

• To translate SNOMED CT into another language
• To add terms that are preferred or accepted within a local setting, for example
  • Common clinical terms that facilitate searching for concepts
  • Patient friendly terms
• To support the creation of new concepts in the extension, which each require at least two descriptions

Principles

Overview

As depicted in, a description in an extension may refer to any concept in the same extension (Extension B), any concept in a module upon which the extension modules depend (Extension A), or any concept in the International Edition.

...

Note that the green and orange triangles pointing to the purple circle represent a situation in which a description is added to an extension that describes an international concept. These extension descriptions supplement the descriptions that are already part of the International Edition.

Adding Descriptions for a New Concept

Descriptions in SNOMED CT are represented in a description file. At least two descriptions must be created for each new concept in an extension: 

...

The acceptability of new descriptions must be specified in a language reference set.

Adding Fully Specified Names

The following principles apply to adding FSNs in an extension.

• There may be more than one active description with a typeId of

  Concept
  ShowParts term t 900000000000003001 |Fully specified name|

   (FSN).
  • However, only one FSN should be marked as preferred for use in a given language or dialect by a specific Language Reference Set.
• Every extension concept must have an unambiguous FSN in US English.
  
  • The US English FSN is the point of reference for the meaning of all concepts in the SNOMED CT International Edition.
  • The US English FSN is used to facilitate sharing and to resolve potential issues related to the interpretation of the meaning.
• Extensions producers are permitted to create a FSN in each of their native languages.
  • This means that a non-English FSN may be marked as the preferred FSN in a specific language reference set in the extension.
  • Consequently, a concept may have more than one FSN. However, only one may be preferred in a specific language reference set. 
  • Where a concept has only one active description with a typeId of

    Concept
    ShowParts term t 900000000000003001 |Fully specified name|

     across all language codes within a release, then that description can be assumed to be the FSN for all languages and dialects, and need not be explicitly included in every language reference set.

Adding Synonyms

• Unlike FSNs, synonyms are not necessarily unique between concepts, as the same term can be used to describe more than one concept.
• The preferred term is the synonym marked as preferred for use in the Language Reference Set for a given language or dialect.
  • There must be at least one description with a typeId of 

    Concept
    ShowParts term t 900000000000013009 |Synonym|

     and an acceptabilityId value of

    Concept
    ShowParts term t 900000000000548007 |Preferred|

     for each concept associated with a description in a given language reference set.

Adding Descriptions to an Existing Concept

When a description is created in an extension, as part of a translation or to provide a localized synonym for an existing concept, a new row should be added in the relevant language reference set to indicate whether the description is 

Process

The table below provides a summary of the process to follow when adding new descriptions to an extension. 

...