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When it comes to understanding the various standardized code sets linked to clinical terminology, it’s easy to get overwhelmed. But don’t fret; this handy 2025 guide answers foundational questions about SNOMED CT and provides some additional resources that will have you up to speed in no time.
What is SNOMED CT?
SNOMED CT stands for Systemized Nomenclature of Medicine – Clinical Terms. It is a standardized, international, multilingual core set of clinical healthcare terminology that can be used in electronic health records (EHRs). SNOMED International is the non-profit standards development organization that creates and distributes SNOMED CT, and it is operated by the International Health Standards Development Organization.
Why is SNOMED CT used?
SNOMED CT represents coded terms that may be used within EHRs to capture, record, and share clinical data for use in healthcare organizations. It is a key component supporting solutions that enable the retrieval of meaningful clinical information. SNOMED CT terms, or codes, have been used internationally for years, and they became widely used in the United States after 2013 when the federal government required EHRs to include the terminology in their systems in order be compliant with Stage 2 of Meaningful Use.
GUIDE
Cracking the codes: A guide to healthcare's standardized coding systems
Learn about SNOMED CT and other standardized code sets like ICD-10-CM, LOINC®, and CPT®.
How is SNOMED CT maintained?
SNOMED International continuously updates content mainly based on user needs and feedback. Updates to SNOMED CT International are released on the first of the month, which is a notable change as of 2022. Previously, SNOMED CT was updated twice annually, on January 31 and July 31. The United States edition of SNOMED CT, however, is still updated twice a year, in March and September. The US Edition of SNOMED CT is maintained by the National Library of Medicine (NLM), which is part of the National Institutes of Health (NIH).
What do the codes look like?
SNOMED CT codes are numerical and are a minimum of six digits long. For instance, 271737000 is the unique code for the SNOMED concept anemia (disorder).
How is the terminology organized?
There are four primary categories of SNOMED CT: concepts, descriptions, relationships, and reference sets:
Concepts
Concepts, or terms, are represented by unique codes and human readable descriptions. Each concept is a unique clinically relevant thought, across a wide range like abscess, zygote, measurement procedure, or substance, as examples. Currently, SNOMED CT contains approximately 370,934 concepts and is organized by relationships. These relationships are then used to turn SNOMED CT into a hierarchy that starts general at the top and gradually become more granular.
Descriptions
Descriptions are human readable terms linked to concepts. Concepts can have multiple descriptions, each of which is a synonym of the original concept.
Relationships
In order to provide meaning to SNOMED concepts, SNOMED uses relationships between concepts to provide formal definitions and organization. For instance, the SNOMED concept chest pain is formally defined with two relationships: an ‘is a’ type relationship to pain that has a ‘finding site’ relationship to thoracic structure.
Reference Sets
Reference sets are used to customize a version of SNOMED CT or to provide a collection of SNOMED concepts. Examples of reference sets are: The designation of language preferences for specific terms, mapping to other code systems, and a collection of concepts relevant to a medical specialty.
Up to speed on SNOMED CT? Find more 101-style guides, here.
References: Vendor Introduction to SNOMED CT and SNOMED CT Compositional Grammar Specification and Guide
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