SNOMED CT — Systematized Nomenclature of Medicine Clinical Terms
Overview
SNOMED CT is a comprehensive clinical healthcare terminology maintained by SNOMED International. It contains over 350,000 active concepts as of 2024, covering diseases, clinical findings, procedures, body structures, substances, organisms, and observable entities, all described with formal, machine-readable definitions and organised in a polyhierarchical structure. It was first released in 2002 from the merger of SNOMED RT (College of American Pathologists) and Clinical Terms Version 3 (UK NHS).
Concept Model
SNOMED CT uses a description logic model in which concepts are formally defined by typed relationships to other concepts. Each concept has a unique numeric SCTID, human-readable descriptions (Fully Specified Name, Preferred Term, Synonyms), and IS-A and attribute relationships that define its meaning and position in the hierarchy.
Relationship to ICD
SNOMED CT and ICD-10 serve different purposes and coexist in clinical systems rather than competing. SNOMED CT is a relational terminology: concepts are defined by typed relationships and sit in a polyhierarchy, so a single finding can belong to several parent categories at once and software can query across them (every infectious lung disease, for example). This supports detailed recording at the point of care and computational reuse. ICD is a flat statistical classification with far fewer codes, each placed in exactly one mutually exclusive category, which is what makes it suited to counting, reporting, and billing. The two are reconciled through a maintained SNOMED-CT-to-ICD map, so care recorded in SNOMED can be reduced to ICD codes for statistics, with detail lost in that direction but not added.
Connections
- relatedTo: EHDS (SNOMED CT is a referenced clinical terminology for EHR content under EHDS, not a mandated standard)
- correspondsWith: ICD-10
- correspondsWith: ICD-11
- relatedTo: ANS (ANS is the French National Release Centre responsible for SNOMED CT in France)
Resources
- https://www.snomed.org
- https://browser.ihtsdotools.org (SNOMED CT browser)
- https://www.snomed.org/snomed-ct/get-snomed (licensing and national releases)
- https://esante.gouv.fr/terminologies (ANS, French NRC)