Mapping to SNOMED CT
Defining the map scope
SNOMED CT contains a number of hierarchies, each representing different types of concepts. When mapping to SNOMED CT, it's important to understand the scope of the source content that you are mapping so you can define the SNOMED CT scope appropriately. When mapping to SNOMED CT, you should constrain the target scope to a specific hierarchy, subhierarchy or subset of SNOMED CT. This will improve the accuracy of any automated mapping tools you may be using and reduce the risk of errors caused by users developing the map.
Example scopes:
If you are mapping a type of organ or body site, then the map scope might be the ‘Body structure’ hierarchy ( < 123037004 |Body structure (body structure)|) http://snomed.info/id/123037004
If you're mapping conditions, judgements or assessments about a patient, the scope might be the Clinical finding hierarchy ( < 404684003 |Clinical finding (finding)|) http://snomed.info/id/404684003
Mapping process
During the map process, once the target scope has been defined to the appropriate hierarchy, subhierarchy or subset of SNOMED CT, authors and reviewers can then search for an appropriate code to map to.
When selecting a code, the user must review the concept’s Fully Specified Name and defining relationships to understand the intended meaning of each concept, and use the use case and rules of the map (such as requirements for equivalence, allowance for 1:many maps, context of implementation, etc) to determine what is an appropriate match.
An example process a user may conduct is:
search SNOMED CT for a matching concept
find an appropriate candidate concept
assign it to the source code with a relationship type
There may be instances where there is more than one candidate concept; depending on the map's rules, it may be appropriate to select more than one. It may also be appropriate to select the most general supertype concept that completely matches the required semantics.
Where there are no appropriate SNOMED CT concepts available, it may be appropriate to
Create or request an appropriate pre-coordinated concept in an extension to be used in the map
Use a SNOMED CT postcoordinated expression that captures the requirements, if the use case of the map can support this
Define the map as having no map target
Last updated