Introduction
The US Edition of SNOMED CT is the official source of SNOMED CT for use in US healthcare systems. It is comprised of:
- The International Release of SNOMED CT
- The US Extension to SNOMED CT, a formal extension to the International Release containing US-specific content (concepts, descriptions, relationships, and history).
The main purposes of the US Edition are to:
- Provide "rapid" access to concept IDs for use by implementers, pending action by IHTSDO on content submissions likely to be added to the International Release of SNOMED CT.
- Provide standard terminology needed for US clinical use cases, but not generally useful in other countries, e.g., regulatory or legislatively mandated terms specific to the US.
- Eliminate the need to combine the US Extension with the International Release thus avoiding potential data integrity problems resulting from concepts in the US Extension referencing parent concepts only available in the International Release.
The International Release of SNOMED CT will continue to be separately available to UMLS Licensees from the SNOMED CT International Edition page. The US Extension to SNOMED CT is no longer provided as a separate file (the final release was March 2013); US Extension content will only be available through the US Edition of SNOMED CT.
The US Edition was developed to facilitate the use of SNOMED CT as the primary coding terminology for clinical information in electronic health records, research databases and clinical trial databases, except in the domains of medications and tests, which are covered by RxNorm and LOINC respectively. As local vocabularies often provide variable ways of representing commonly used concepts, the use of a common list of SNOMED CT concepts will maximize data interoperability among institutions. The US Edition streamlines installation and use of US-specific SNOMED CT content found in the US Extension. Users unable to find terms they think are appropriate should submit additional SNOMED CT content requests to NLM through the US SNOMED CT Content Request System (USCRS).
Please Note: The March 2017 Release of the US Edition of SNOMED CT will mark the last time that NLM will make the RF1 release file available for download. For future releases, users must download the RF2 version of the US Edition of SNOMED CT.
Related Documents
File Description
The US Edition of SNOMED CT is distributed in two formats: Release Format 1 (RF1), and Release Format 2 (RF2). US Edition files correspond to SNOMED CT files as described in the SNOMED CT® Technical Implementation Guide, International Release.
Update and Maintenance
A new version of the US Edition will be published approximately one month after each new release of the International Release of SNOMED CT. A history file will be provided with each release of the US Edition to document the type and resolution of changes to the US-specific content.
SNOMED CT License Requirement
SNOMED CT is owned by the International Health Terminology Standards Development Organisation (IHTSDO), of which NLM is the US Member. Use of SNOMED CT is subject to the IHTSDO Affiliate license provisions (incorporated in the License Agreement for Use of the UMLS® Metathesaurus® as Appendix 2) and is free in IHTSDO Member countries including the United States, in low income countries, and for Qualifying Research Projects in any country. See the SNOMED CT Licensing page for more information.
Feedback and Suggestions
We welcome any questions, comments or suggestions that would improve the quality, accuracy and usability of the extension. Please send feedback via the Contact NLM NLM Customer Service form. Please be sure to include the subject line "SNOMED CT US Edition."
Acknowledgements
We would like to thank and acknowledge the contributions of Julie Green and Jeff Wilcke of the Veterinary Terminology Services Laboratory at Virginia Tech, and Ian Green and Ian Arrowsmith of the United Kingdom Terminology Centre for their expertise and advice during the development of the US Extension. We also thank all past and current UMLS licensees who have submitted content for consideration to the US Extension and their continued input and data that define the extension content.