1. Q. What is SNOMED CT?
   
   A. SNOMED Clinical Terms (SNOMED CT) is an extensive clinical terminology that was formed by the merger, expansion, and restructuring of SNOMED RT® (Reference Terminology) and the United Kingdom National Health Service (NHS) Clinical Terms (also known as the Read Codes). It is the most comprehensive clinical vocabulary available in English (or any language). SNOMED CT is concept-oriented and has an advanced structure that meets most accepted criteria for a well-formed, machine-readable terminology. It has been designated as a US standard for electronic health information exchange in Interoperability Specifications produced by the Healthcare Information Technology Standards Panel and has also been adopted for use by the U.S. Federal Government, through the Consolidated Health Informatics (CHI) Initiative, for several clinical domains.
   
   
2. Q. Who owns SNOMED CT?
   
   A. SNOMED CT was acquired in April 2007 by the International Health Terminology Standards Organisation (IHTSDO). The IHTSDO purchased the intellectual property of SNOMED CT and antecedent works from the College of American Pathologists (CAP), which created and maintained it for more than 40 years. The goal of the change in ownership was to promote international adoption and use of SNOMED CT. The IHTSDO is responsible for ongoing maintenance, development, quality assurance, and distribution of SNOMED CT. The CAP will continue to support SDO operations under contract and to provide SNOMED-related products and services as a licensee of the terminology.
   
   
3. Q. How is the U.S. represented in the international organization that owns SNOMED CT?
   
   A. NLM is the U.S. Member of the IHTSDO - one of the nine original Charter Members. As an IHTSDO member, NLM has rights and responsibilities that include the distribution of SNOMED CT (both English and Spanish versions) in multiple formats. Details are available in the IHTSDO Articles of Association. NLM supports this effort through a contract with the IHTSDO under which NLM pays an annual fee (approximately $6 million per year) to make SNOMED CT available free of charge to anyone in the U.S.
   
   NLM is a voting member of the General Assembly of the IHTSDO and serves as a focal point for U.S. input to the ongoing development of the terminology. The U.S. is currently represented on the IHTSDO Management Board by Andrew Wiesenthal, MD, SM, Kaiser Permanente. Permanent executive officers have been appointed including Kent Spackman, MD, Oregon Health Sciences University, as the Chief Terminologist.
   
   The IHTSDO has four standing Committees: Content, Research & Innovation, Quality Assurance, and Technical. Potential committee members are nominated by each member country and voted on by the IHTSDO’s General Assembly. NLM coordinates the committee nominations for the U.S. SNOMED CT users may also volunteer for working groups, project groups, and special interest groups. Interested parties should e-mail NLM Customer Service for more details.
   
   NLM is working to establish the U.S. process for submitting requests for additions or enhancements to SNOMED CT content.
   
   
4. Q. What impact does the change in SNOMED CT ownership have on existing UMLS Licensees?
   
   A. UMLS licensees must review and accept a revised License Agreement for Use of the UMLS Metathesaurus, which incorporates the uniform international IHTSDO Affiliate Licence, by MAY 15, 2007 in order to ensure uninterrupted access to the UMLS Knowledge Source Server. Click here to complete this easy online process.
   
   In addition to access to SNOMED CT within the UMLS Metathesaurus, UMLS licensees will also have free access from NLM to SNOMED CT in its native file formats (effective May 15, 2007), to the documentation of these files, and to a growing set of subsets and mapping files.
   
   UMLS licensees have broader rights to create and distribute SNOMED CT extensions and derivative works under the uniform international IHTSDO Affiliate Licence that is now part of the UMLS License. The license covers all types of use in all countries. Fees apply to some types of distribution or use in countries that are not yet Members of the IHTSDO.
   
   
5. Q. What SNOMED CT content is in the UMLS Metathesaurus?
   
   A. The UMLS Metathesaurus contains the complete SNOMED CT in English and Spanish. For the specific versions that are included in each edition of the UMLS Metathesaurus, consult the documentation for that edition.
   
   
6. Q. How is SNOMED CT represented in the UMLS Metathesaurus?
   
   A. The UMLS Metathesaurus includes many different vocabularies in a common, explicit, concept-based format. SNOMED CT has been converted to the common UMLS format, its concept names have been connected to those already in the Metathesaurus, and its content has been assigned UMLS identifiers, semantic types, etc. See Explanatory Notes for additional details, including a mapping between SNOMED’s tables and fields and the tables and fields in the Metathesaurus
   
   
7. Q. How can I extract SNOMED CT from the UMLS Metathesaurus and browse it?
   
   MetamorphoSys, free Java software, is distributed with the UMLS to assist users in producing subsets of the Metathesaurus. It includes some predefined filters for generating subsets that include SNOMED. Users are able to modify filters and defaults to generate a desired subset of the Metathesaurus, or write their own custom filters. Any output from MetamorphoSys includes some basic UMLS Metathesaurus data, e.g., NLM Concept Unique Identifiers (CUIs) as well as Lexical Unique Identifiers (LUIs), and String Unique Identifiers, SUIs). The UMLS RRF Browser, also free Java software distributed with the UMLS content, allows users to browse any subset output by MetamorphoSys.
   
   
8. Q. Where can I read more about the UMLS, the current file formats, the sources included, etc.?
   
   A. The current UMLS documentation is available here. The current UMLS license, which includes an appendix that lists all vocabularies currently in the Metathesaurus and the IHTSDO Affiliate licence for use of SNOMED CT, is available here.
   
   
9. Q. Where can I get SNOMED CT in its native file format?
   
   A. Effective MAY 15, 2007, UMLS licensees may obtain the English and Spanish editions of SNOMED CT in their native file formats from the UMLS Knowledge Sources Server. In the future, the native file formats of SNOMED CT will also appear on the UMLS DVD.
   
   
10. Q. Does NLM also distribute the CLUE Browser?
    
    A. No. NLM does not distribute the CLUE Browser or the SNOMED CT files in the format needed by the CLUE Browser. UMLS licensees may browse SNOMED CT content in the UMLS Knowledge Source Server or the UMLS RRF Browser, which is distributed as part of MetamorphoSys. SNOMED CT data in CLUE browser format is available for purchase from the College of American Pathologists.
    
    
11. Q. How can I submit concepts that do not appear in SNOMED CT to the IHTSDO for review/ inclusion?
    
    A.  The International Health Terminology Standards Development Organisation (IHTSDO), of which NLM is the US Member, has set a high priority on the development of a SNOMED CT concept request submission system.   Policies, procedures and tools for submission, evaluation and processing of requests must be developed and tested.  Until this system is implemented, we encourage you to submit requests via NLM Customer Service.  NLM will use this information to better understand the needs of SNOMED CT users, and to work with the IHTSDO to develop procedures and tools that facilitate request processing. 

    You may send SNOMED CT concept suggestions to NLM Customer Service  (custserv@nlm.nih.gov).  Please include "SNOMED CT Concept Request" in the Subject line and the following information:

    1.  Suggested concept.  Include synonyms or alternate forms used.
    2.  Definition. 
    3.  How is it used? Include some information about the sense or context in which the term occurs and how frequently it is likely to be used.
    4.  What is the nearest SNOMED CT concept?  
          -How does the suggested concept relate to its nearest SNOMED CT concept(s)? 
          -For example, is it a more detailed or specific form of a broader concept in SNOMED CT?  If it is more specific, why is the distinction involved important in your context?
    5.  How do you use SNOMED CT in your organization or application? 
          - For example:  electronic medical records, clinical decision support, medical research studies, clinical trials, computerized physician order entry, disease surveillance, image indexing
    6.  Whom may we contact for additional information or follow-up?

    • Contact name
    • Title
    • Organization
    • Address
    • Telephone number
    • Email address     
    • UMLS Licensee Name (if not the contact)
    • UMLS License Number

    Suggestions will be reviewed for warrant and other criteria of usefulness, reproducibility in use and for understanding.    Please include as much of the above information as possible with your submission.   We value your contributions to SNOMED CT and look forward to hearing from you. 

Last reviewed: 15 December 2008
Last updated: 15 December 2008
First published: 01 July 2003
Metadata| Permanence level: Permanence Not Guaranteed