SNOMED CT

Key facts

Owned by

SNOMED International, a not-for-profit standards organization

U.S. distributor

National Library of Medicine, the U.S. National Release Center

U.S. license cost

Free for U.S. use under the UMLS license

Identifier

Numeric SNOMED CT identifier (SCTID)

What is SNOMED CT?

SNOMED CT is a clinical terminology: a very large, structured collection of medical concepts with codes, names and defined relationships. Clinicians rarely see the codes. When a physician picks "type 2 diabetes mellitus" from an electronic health record (EHR) problem list, the system typically stores a SNOMED CT concept behind the displayed term.

It is owned and maintained by SNOMED International, a not-for-profit organization whose members are mostly national governments. It grew out of the merger of the College of American Pathologists SNOMED with the UK Clinical Terms (Read Codes). The United States is a member, so the National Library of Medicine (NLM) distributes SNOMED CT free of charge for U.S. use and publishes a US Edition with U.S.-specific content.

How SNOMED CT is organized

The terminology is built from a few core components:

Because concepts are defined by relationships, software can query at any level of detail, for example retrieving every patient with any type of pneumonia.

• Concepts: clinical meanings, each with a numeric identifier (SCTID).
• Descriptions: a fully specified name plus synonyms that users can search and display.
• Relationships: "is a" links build hierarchies (viral pneumonia is a pneumonia), and attribute relationships define meaning, such as finding site or causative agent.
• Top-level hierarchies: including clinical finding, procedure, body structure, organism, substance, and pharmaceutical or biologic product.

Why SNOMED CT matters

SNOMED CT is the language of clinical data inside U.S. EHRs:

• Federal health IT certification and the United States Core Data for Interoperability (USCDI) name SNOMED CT, alongside ICD-10-CM, for patient problems.
• Real-world evidence studies built on EHR data often define patient cohorts with SNOMED CT concepts rather than billing codes.
• NLM publishes a map from SNOMED CT to ICD-10-CM that helps turn clinical documentation into billing codes.

SNOMED CT vs ICD-10-CM

SNOMED CT is a detailed terminology built to capture clinical meaning at the point of care. ICD-10-CM is a classification that groups conditions into mutually exclusive categories for billing and statistics. One ICD-10-CM code can correspond to many SNOMED CT concepts, and SNOMED CT is not used to bill U.S. claims.