How does SNOMED CT define SNOMED_CID?

Question

Each of the concepts in SNOMED CT has the conceptId (SNOMED_CID). Could you please let me know how SNOMED CT defines the SNOMED_CID. Is there any numbering scheme that SNOMED CT follows? SNOMED terms are also available in UMLS. What numbering scheme UMLS follow to define UMLS CUI?

Answer 1

A SNOMED CT concept identifier is a 6-digit to 18-digits string of the form

<ITEM-ID><NAMESPACE-ID><N>0<D>

where

• <ITEM-ID> is the 'actual identifier' identifying the concept within the provider,
• <NAMESPACE-ID> is either empty string ( <N> is a single digit 0 ) and the concept was issued by SNOMED International; or a 7-digit namespace identifier ( <N> is a single digit 1 ) issued by SNOMED International to an organization permitted to create and manage their own SNOMED concepts (extension).
• <D> is a single check digit computed by https://en.wikipedia.org/wiki/Verhoeff_algorithm

For example, 1290023401004 is a valid SNOMED concept identifier created by SNOMED international (<N> is 0) with item id 1290023401, while 11000001102 is a valid SNOMED concept identifier created by NHS Digital (namespace 1000001, see https://cis.ihtsdotools.org/info/index.html?home=namespaces , <N> is 1) with item id 1.

Details on SNOMED identifiers can be found in https://confluence.ihtsdotools.org/display/DOCRELFMT/6+SNOMED+CT+Identifiers.