SNOMED CT Snapshot Relationship

$716 / year

This dataset describes the Release File structure of SNOMED CT, referred to as Release Format 2 (RF2). The US Edition of SNOMED CT is the official source of SNOMED CT for use in US healthcare systems. The US Edition is a standalone release that combines the content of both the US Extension and the International release of SNOMED CT.

The Relationship file holds one relationship per row. Each relationship is of a particular type, and has a source concept and a destination concept.


SNOMED CT (SNOMED Clinical Terminology) provides a common language that assists with the electronic exchange of clinical health information. It enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care. SNOMED CT Can be mapped to other coding systems, such as ICD-10, which helps facilitate semantic interoperability.

A Snapshot release contains the most recent version of every component released up to the time of the snapshot. The version of each component contained in a snapshot is the most recent version of that component at the release time. The ‘Snapshot’ release is useful for a simple installation but does not provide a history or retrospective view of the terminology. There are valid use cases for each Release Type. Each International release will incorporate all three of these Release Types, allowing users to choose the most appropriate format.

In addition to 623 new concepts specific for the US, the September 2018 SNOMED CT US Edition also contains all of the content from the July 2018 SNOMED CT International Edition. Approximately 543 requests for terminology additions and updates were submitted via the US Content Request System (US CRS) to support US clinical health information data exchange. This latest version of the US Edition also includes the SNOMED CT to ICD-10-CM reference set, with over 123,000 SNOMED CT source concepts mapped to ICD-10-CM targets.

Date Created


Last Modified




Update Frequency


Temporal Coverage


Spatial Coverage

United States


John Snow Labs; International Health Terminology Standards Development Organisation (IHTSDO), U.S. National Library of Medicine (NLM);

Source License URL

Source License Requirements

Reporting Requirements

Source Citation



Clinical Terminology, SNOMED CT, IHTSDO, Systematized Nomenclature of Medicine Clinical Terms, Healthcare Terminology, Electronic Health Records, Machine Readable Concept Model

Other Titles

SNOMED CT United States Edition, SNOMED CT Latest Version, Machine Readable Concept Model of SNOMED CT

Relationship_IdUniquely identifies the relationship.integerlevel : Nominal required : 1
Effective_DateSpecifies the inclusive date at which the component version's state became the then current valid state of the componentdaterequired : 1
Is_ActiveSpecifies whether the relationship's state was active or inactive from the nominal release date specified by the Effective_Datebooleanrequired : 1
Module_IdIdentifies the relationship version's module.integerlevel : Nominal required : 1
Source_IdIdentifies the source concept of the relationship version, i.e., the concept the relationship version emanates from.integerlevel : Nominal required : 1
Destination_IdIdentifies the concept that is the destination of the relationship version.integerlevel : Nominal required : 1
Relationship_GroupGroups together relationship versions that are part of a logically associated relationship group. All active Relationship records with the same Relationship_Group number and Source_Id are grouped in this way.integerlevel : Ordinal required : 1
Type_IdA concept enumeration value from the metadata hierarchy that identifies the semantic type of the relationship version.integerlevel : Nominal required : 1
Characteristic_Type_IdA concept enumeration value that identifies the characteristic type of the relationship version (i.e. whether the relationship version is defining, qualifying, etc.)integerlevel : Nominal required : 1
Modifier_IdA concept enumeration value that identifies the type of Description Logic (DL) restriction (some, all, etc.).integerlevel : Nominal required : 1
Relationship IdEffective DateIs ActiveModule IdSource IdDestination IdRelationship GroupType IdCharacteristic Type IdModifier Id