Table Of Contents

Introduction

Background

SNOMED CT provides a common language that enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care.

SNOMED International maintains the SNOMED CT technical design, the content architecture, the SNOMED CT content (includes the concepts table, the descriptions table, the relationships table, a history table, and ICD mappings), and related technical documentation.

Purpose

This document provides a summarized description of the content changes included in the November 2025 release of SNOMED Clinical Terms^® (SCT) International Edition.

It also includes notes detailing the known content or technical issues where the root cause is understood, the fix has been discussed and agreed to, but has yet to be implemented.

The SNOMED International release notes are available alongside the November 2025 International Edition.

Scope

This document is written for the purpose described above and is not intended to provide details of the technical specifications for SNOMED CT or encompass every change made.

Audience

The audience includes National Release Centers, WHO-FIC release centers, vendors of electronic health records, terminology developers and managers who wish to have an understanding of changes that have been incorporated into the November 2025 International Edition.

Please note, you may have to register for a user account in order to access the links included in these release notes.

Content Development Activity

Summary

Continuous quality improvement and enhancement of existing content is an ongoing process undertaken by SNOMED International in preparation for every release. The November 2025 International Edition has seen a continuation of the work driven by contributions from: Kaiser Permanente i.e. Convergent Medical Terminology (CMT), Global Medical Device Nomenclature Agency (GMDNA), Orphanet and other domain specific collaborations as well as requests received via the Content Request System (CRS). 

Additionally quality improvement activities are advanced via project driven initiatives summarized below.  Additional work items impacting every release are updates to the SNOMED CT derived maps such as ICD-10 and ICD-O; details are included in these release notes.  

Information about editorial decisions may be found in the SNOMED CT Editorial Guide; mapping guidance for ICD-10 can be found here.

Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 Edition release, the next stage has been implemented for subsequent releases including November 2025. 

Quality improvement tasks are being deployed to improve internal structural consistency and ensure compliance with editorial policy related to the stated modeling of content. Additionally, correction or addition of defining relationships is being carried out to accurately reflect current clinical knowledge and ensure the semantic reliability of descriptions associated with a concept.

Body Structure 

New Concepts - Cell Structure

Approximately 300 new concepts for cell structures denoting cluster of differentiation markers have been added as part of the work for the LOINC project.

For example: 1372909008|Cell positive for CD57 antigen (cell).

SEP and Laterality Anatomy Reference Sets

The release file for the lateralizable body structure reference set has been updated and validated.

The release file for the SEP reference set has been updated and validated.

Procedure

Radiographic Imaging

Work for this Content Tracker (IHTSDO-161) for the hierarchy 363680008|Radiographic imaging procedure (procedure)| has been ongoing.

For the November 2025 release, the work for this project has focused on

<< 241171008 |Gastrointestinal tract loopogram (procedure)|

<<405250000|Retrograde pyelography with contrast (procedure)|

<<168854009 |Cystogram (procedure)|

Subtypes that did not specify an imaging modality/align with the SNOMED CT Editorial Guide have been inactivated and replaced by an imaging specific procedure concept.

The work for this content area is now complete.

Update Radiofrequency Ablation Procedure Concepts

Inconsistencies in descriptions and modeling for concepts relating to radiofrequency ablation has been reported. The content in this area has been reviewed with updates to align the descriptions and model. The subtypes of 371791001|Radiofrequency ablation device (physical object)| relating to cardiac ablation have been reorganized. Content relating to radiofrequency ablation of the nervous system was out of scope for the work undertaken.

Number of concepts edited (approx): 39

Qualifier Value

Inactivation of 272423005|Degrees of severity (qualifier value)| and Subtypes

272423005|Degrees of severity (qualifier value)| and subtypes have been inactivated as these concepts were identified as potentially a duplicate of 272141005|Severities (qualifier value)| by a member country during translation. The degrees of severity subtypes appear to be specific to burns. As the SEVERITY attribute is discouraged for use in the international edition, content relating to burns is modeled with an associated morphology to represent the degree of burn injury so the degrees of severity qualifier values are redundant.

New Concepts Supporting UICC Autopsy TNM Categories, Additional UICC Categories, and Prefixes and Suffixes

A total of 82 new autopsy concepts have been added: the top-level grouping concept 1379985004 |Union for International Cancer Control autopsy (qualifier value)| and subtypes:

• aT category values: 42 new concepts

• aN category values: 20 new concepts

• aM category values: 19 new concepts

Additional UICC categories have also been added (counts include category grouper):

• L category values: 4 new concepts

• LV category values: 4 new concepts

• V category values: 5 new concepts

• H category values: 4 new concepts

In addition, 13 concepts missing from the UICC classification codes have been added:

cN0 mol-, cN0 mol+, pN0 mol-, pN0 i-, ypN0 i-, ypN0 mol-, ycN0 i-, ycN0 mol+, ycN0 mol-, rcN0 i-, rcN0 mol-, rpN0 i-, rpN0 mol-.

Also new prefixes and suffixes have been added to extend the use of the TNM codes. The top level grouper concept is 1380159003 |Union for International Cancer Control allowable prefix and/or suffix value (qualifier value)| with 8 new subtype concepts representing:

• Prefixes: y, r, a

• Suffixes: f, m, sn, mr, PET

Number of concepts added: 121

Collaboration/Harmonization Agreements

Convergent Medical Terminology (CMT)

15 new concepts have been added for the November 2025 release with focus on hematology and oncology.

Orphanet

Working in collaboration with Orphanet efforts are ongoing to update rare disease concepts in SNOMED CT to maintain alignment with Orphanet for the annual update of the SNOMED CT to Orphanet Maps. This map is at disorder level. In scope content has been annotated with attribution to Inserm Orphanet.

All of the concepts added for the Orphanet project have been mapped to ICD-10.

Cancer Synoptic Reporting

Cancer synoptic reports are used by many member countries to record pathology examination of cancer specimens including the College of American Pathologists (US and Canada), Royal College of Pathology (UK), Royal College of Pathology Australasia (Australia, New Zealand), PALGA (The Netherlands), Swedish Society of Pathology, and others.

For more information about this project, please see Cancer Synoptic Reporting Clinical Project Group 

International League Against Epilepsy (ILAE)

In line with approved harmonized terminology, this project is working on alignment including restructuring to update the hierarchy  << 313307000 |Epileptic seizure (finding)|.

Further information about this collaboration is available here.

Internal Quality Improvement

Machine Readable Concept Model (MRCM) Changes

No changes have been made for the MRCM in the November 2025 International Edition.

Future changes that are currently in progress can be viewed via the MRCM Daily Build Browser

Please see Early Visibility Notifications for future planned changes to MRCM.

Annotation Reference Set

The addition of content for the Annotations refset was commenced in the July 2024 International Edition release and is ongoing for attribution of in scope content that is part of a collaboration agreement. Where content with attribution no longer falls into scope for a collaboration agreement, the attribution has been inactivated.

SNOMED CT derived products

SNOMED CT - ICD-10 map

The SNOMED CT to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (© World Health Organization 1994) 2016 Version map (SNOMED CT to ICD-10 Map) is included in the SNOMED CT International Edition as a Baseline. The SNOMED CT to ICD-10 Map was created to support the epidemiological, statistical and administrative reporting needs of SNOMED International member countries and WHO Collaborating Centers.

The SNOMED CT to ICD-10 Map is released in Release Format 2 (RF2) only. It is located in the file der2_iisssccRefset_ExtendedMapFull_INT_20200731.txt, which is in the Map folder under Refset, in each of the three RF2 Release Type folders. 

The SNOMED CT to ICD-10 Map is released as Refset 447562003 |SNOMED CT to ICD-10 extended map (foundation metadata concept).

The ICD-10 Mapping Technical Guide (including exemplars) is here.

Content Development Activity Summary

The map is a directed set of relationships from SNOMED CT source concepts to ICD-10 target classification codes.  The SNOMED CT source domains for the map are constrained to subtypes of 404684003 |Clinical finding (finding)|, 272379006 |Event (event)|, and 243796009 |Situation with explicit context (situation)|. The target classification used is the ICD-10 WHO version 2016 (https://icd.who.int/browse10/2016/en#/).

The map provided for this release has been updated and represents a complete map from the November 2025 release of the SNOMED CT International Edition to the ICD-10 WHO version 2016.

This includes:

Mapped content for November 2025 release

• Addition of 101 new mapped concepts

• Updates to 3 existing mapped concepts

• Retirement of 37 mapped concepts

The SNOMED CT to ICD-O morphology map has no additional new content for this release.

We welcome feedback on any issues that users may detect when deploying the map. Issues can be reported to mapping@snomed.org.

SNOMED CT to OWL conversion and classification

The repository containing the toolkit enabling simple SNOMED CT to OWL conversion and classification can be found here, including documentation on its use: https://github.com/IHTSDO/snomed-owl-toolkit

Please contact SNOMED International at support@snomed.org if you would like to provide any feedback on ways to extend and improve the new toolkit.

Technical notes

Known Issues

Known Issues are content or technical issues where the root cause is understood, and the resolution has been discussed and agreed but has yet to be implemented.  This can be due to a number of reasons, from lack of time within the new monthly editing cycles, to the risk of impact to the stability of SNOMED CT if the fix were to be deployed at that stage in the Product lifecycle.  

For the current SNOMED CT International Edition, the following Known Issues were identified, and agreed to be resolved in future editing cycles:

Resolved Issues

Resolved issues are Known Issues which were not fixed as part of the previous release lifecycle, but which have now been resolved in the latest release.  They can also be issues found during testing of the current release, which were resolved before the final deployment of the Production release.  Finally they can be issues which were reported or found during the testing phase, but which have been closed without any action taken.  

The Resolved Issues for the current SNOMED CT International Edition can be found here:

Technical updates

RF2 package format

The RF2 package convention dictates that all relevant files are included, regardless of whether or not there is content to be included in each release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and files that (intentionally) include only header records.  The reason that these "empty" files are included in the package is to draw a clear distinction between:

1. ...files that have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in future releases 

2. ...files that happen to contain no data in this particular release (and are therefore included in the package with just a header record), but are still relevant to RF2, and could therefore contain content in future releases.

This allows users to easily distinguish between the two scenarios, as otherwise if files in option 2 were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

ADVANCED NOTICE: Increase to the maximum length of Description Types

Please see here for the latest announcement on the plan to increase the limit of characters allowed in Descriptions.

A community consultation was completed to solicit feedback on the proposal to increase the size limits of SNOMED CT concept descriptions to 4096 from the current limit of 255 characters. While this change does not represent a modification of the existing specification, there is a potential for it to be disruptive to implementers who have coded fixed length limits into their systems.  

Please read the full proposal, along with the latest Q&A blog post for details of the planned changes, the potential benefits, and the issues that may need to be considered to prepare for the transition in 2026.

Early visibility of impending changes in the upcoming 2025 Monthly International Edition releases

Please see the Early Visibility Notifications for details of forthcoming changes.