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Unified Medical Language System® (UMLS®)


SNOMED CT is considered to be the most comprehensive, multilingual clinical healthcare terminology in the world. It is designed for use in clinical documentation in the Electronic Health Record (EHR). The purpose of the SNOMED CT to ICD-10-CM map (herein referred to as "the Map") is to support semi-automated generation of ICD-10-CM codes from clinical data encoded in SNOMED CT for reimbursement and statistical purposes.

Current version of SNOMED CT to ICD-10-CM map can be found in the US Edition of SNOMED CT.

More information on how to access the map files can be found in the "File Path" section below.

For older versions of the SNOMED CT to ICD-10-CM map files, please see the SNOMED CT Archives page.


The I-MAGIC (Interactive Map-Assisted Generation of ICD Codes) Algorithm utilizes the SNOMED CT to ICD-10-CM Map in a real-time, interactive manner to generate ICD-10-CM codes. This demo simulates a problem list interface in which the user enters problems with SNOMED CT terms, which are then used to derive ICD-10-CM codes using the Map.

I-MAGIC Demo Page

I-MAGIC Implementation Guide

Additional Information

Use Cases Supported

The Map can be used in the following scenarios:

  • Real-time use by the healthcare provider - In this scenario, the Map is embedded in the problem list application of the EHR used by the physician or other healthcare provider. At the end of a clinic encounter, the clinician updates the problem list, which is encoded in SNOMED CT. The Map-enabled problem list application outputs a list of ICD-10-CM codes based on algorithmic evaluation of map rules, which makes use of patient context (e.g. age, gender) and co-morbidities (other problems on the problem list) to identify the most appropriate candidate ICD-10-CM codes, in accordance with ICD-10-CM coding guidelines and conventions. If necessary, the clinician is prompted for additional information to decide between alternative codes, or to refine the output codes. The clinician confirms the suggested ICD-10-CM codes. (See the I-MAGIC algorithm and demo page)
  • Retrospective coding by coding professionals - In this scenario, the Map is used within an application to suggest candidate ICD-10-CM codes to coding professionals based on a stored SNOMED CT encoded problem list. The degree of automation can vary. Textual advice can be displayed in cases where automated rule processing is not available.

Supporting Materials

Mapping Methodology

The mapping methodology follows closely that of the SNOMED CT to ICD-10 Crossmap Project, a collaborative project between the IHTSDO and the World Health Organization. Dual independent mapping by trained terminology specialists is employed to assure quality and reduce variability. Identical maps created independently are accepted as final, while discordant maps are reviewed by a third expert. Regular team meetings are held to discuss problematic and ambiguous cases.

Rule-based Mapping

Due to the differences in granularity, emphasis and organizing principles between SNOMED CT and ICD-10-CM, it is not always possible to have a one-to-one map between a SNOMED CT concept and an ICD-10-CM code. To address this challenge, this Map follows an approach that is consistent with the approach used by the IHTSDO and WHO in the construction of the SNOMED CT to ICD-10 rule-based map. When there is a need to choose between alternative ICD-10-CM codes, each possible target code is represented as a “map rule” (the essence of "rule-based mapping"). Related map rules are grouped into a "map group". Map rules within a map group are evaluated in a prescribed order at run-time, based on contextual information and co-morbidities. Each map group will resolve to at most one ICD-10-CM code. In the event that a SNOMED CT concept requires more than one ICD-10-CM code to fully represent its meaning, the map will consist of multiple map groups.


All active pre-coordinated SNOMED CT concepts within three hierarchies, (Clinical findings, Events, and Situations with Explicit Context) are potentially in scope for mapping to ICD-10-CM. All concepts within scope included in the immediate past release of the US Extension are mapped in the current release of the Map.

Release Schedule

The Map is updated with each new SNOMED CT US Edition release (March and September) and includes the annual ICD-10-CM update.

File Path

The SNOMED CT to ICD-10-CM map is released as Refset 6011000124106 | ICD-10-CM complex map reference set (foundation metadata concept)|. The map data are in the file der2_iisssccRefset_ExtendedMap (Full/Snapshot)_US1000124_YYYYMMDD.txt, which is in the Map folder under Refset in each release type folder (Full/Refset/Map or Snapshot /Refset/Map).

Fig 1: File Path
Figure 1: File Path
Fig 2:Refsetid 6011000124106
Figure 2: Refsetid 6011000124106

The map is also available in a human readable format (tls_Icd10cmHumanReadableMap_US1000124_YYYYMMDD.tsv) and can be downloaded from the US Edition page.

License Requirements

In accordance with NLM’s mapping assumptions, the Map can be used by users that are licensed to use both SNOMED CT and ICD-10-CM. SNOMED CT is owned by the International Health Terminology Standards Development Organisation (IHTSDO). The NLM is the U.S. Member of the IHTSDO and, as such, distributes SNOMED CT at no cost in accordance with the Member rights and responsibilities outlined in the IHTSDO's Articles. The license terms are incorporated into the License for Use of the UMLS Metathesaurus. Use of SNOMED CT is subject to the IHTSDO Affiliate license provisions and is free in IHTSDO Member territories including the United States, in low income countries, and for Qualifying Research Projects in any country.

To request a license click "Sign Up" on the UTS Homepage. Additional information can be found on the UMLS License page. The use of ICD-10-CM is free in the US. Users in other countries may need to contact WHO for the use of ICD-10-CM.

Feedback and Suggestions

We welcome any questions, comments or suggestions that would improve the quality, accuracy, and usability of the subset. Please send feedback through the NLM Customer Support form with the subject line "SNOMED CT to ICD-10-CM Map".


We thank Dr. James Campbell (University of Nebraska) and Dr. David Berglund (National Center for Health Statistics in the Centers for Disease Control and Prevention) for their contributions to the project. We made significant use of mapping data previously produced by the IHTSDO and the UK National Health Service (NHS) Terminology Centre, which provided access to data and tools from the SNOMED CT to ICD-10 Crossmap Project, and Kaiser Permanente, which included basic mappings to ICD-10-CM in some of their CMT content. We thank the IHTSDO, the UK NHS Terminology Centre, and Kaiser Permanente for these contributions, which significantly reduced the resources and time required to produce the SNOMED CT to ICD-10-CM Map. We also thank CAP SNOMED Terminology Solutions Professional Services of the College of American Pathologists for their review of a subset of the Map and useful feedback.

Last Reviewed: March 1, 2021