1. Introduction

1.1. Background

SNOMED CT terminology 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.

1.2. Purpose

This document provides a summarized description of the content changes included in the September 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 September 2025 International Edition.

1.3. 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.

1.4. 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 September 2025 International Edition.

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

2. Content Development Activity

2.1. Summary

Continuous quality improvement and enhancement of existing content is an ongoing process undertaken by SNOMED International in preparation for every release. The September 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.

2.2. 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 September 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.

2.2.1. Update Descriptions for Neonatal/Newborn

Concepts with descriptions relating to 'neonate' and 'newborn' have been updated to improved consistency in the use of these terms.

2.3. Body Structure 

2.3.1. Update Hierarchy 91272006|Chromosome (cell structure)|

The hierarchy 91272006|Chromosome (cell structure)| and subtypes have been revised following the anatomy SEP (Structure/Entire/Part) model. These changes will facilitate the future inclusion of concepts referring to gene structures. 

Further information is available here.

New concepts have been added for chromosome 1 - 23. The existing duplication of chromosome 23 and sex chromosome has been resolved.

Disorders related to chromosome will be addressed in future changes.

2.3.2. Inactivation of 312419003 |Structure of respiratory system and/or intrathoracic structure (body structure)|

The concept 312419003 |Structure of respiratory system and/or intrathoracic structure (body structure)| has been inactivated. Related disorder and procedure concepts have been remodeled by respiratory system and thoracic content and/or cavity which has improved the classification results.

Number of concepts edited (approx): 6

2.3.3. 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.

2.4. Clinical Finding

2.4.1. Update Hierarchy 309465005|Varicella-zoster virus infection (disorder)|

Following requests from members that translate SNOMED CT, updates have been made to the 309465005 |Varicella-zoster virus infection (disorder)| hierarchy to improve consistency in the FSN and to support accurate translation into other languages.

Issues Identified:

• Inconsistent naming: Disorders caused by reactivation of Varicella-zoster virus (herpes zoster/shingles) used varied naming patterns, including:
  • X due to herpes zoster
  • X caused by herpes zoster
  • Herpes zoster X
  • X caused by Human alphaherpesvirus 3 (with a synonym Herpes zoster X)
• Inconsistent modeling: Inappropriate use of the DUE TO relationship was identified in some concepts, where the underlying cause is reactivation of the virus rather than another disorder.

Changes Implemented:

• Standardized FSN pattern: All relevant concepts now follow this pattern:
  • FSN: X caused by reactivation of Varicellovirus humanalpha3 (disorder)
  • PT: Herpes zoster X
• Improved modeling: The DUE TO relationship has been inactivated where inappropriate. For example, 1087131000119102 |Scleritis due to herpes zoster (disorder)| has been updated to:
  • FSN: Scleritis caused by reactivation of Varicellovirus humanalpha3 (disorder)
  • PT: Herpes zoster scleritis.
• The concept retains:
  • AFTER = 38907003 |Varicella (disorder)|
  • CAUSATIVE AGENT = 19551004 |Varicellovirus humanalpha3 (organism)|

These changes ensure consistent naming and modeling of herpes zoster-related disorders, supporting accurate representation and translation.

2.4.2. Update Hierarchy 395507008|Premature infant (finding)|

The hierarchy 395507008|Premature infant (finding)| has been updated to remove overlapping gestational weeks and to improve the concepts relating to range. Changes made include:

• New concepts added:
  • 1371409000 |Preterm infant less than 37 completed weeks gestation (finding)|
  • 1371413007 |Late preterm infant from 34 weeks up to 36 weeks and 6 days gestation (finding)|
  • 1371412002 |Moderate preterm infant from 32 weeks up to 33 weeks and 6 days gestation (finding)|
  • 1371411009 |Very preterm infant from 28 weeks up to 31 weeks and 6 days gestation (finding)|
  • 1371410005 |Extremely preterm infant less than 28 completed weeks gestation (finding)|
  • 1373207005 |Baby premature 24 weeks to 25 weeks and 6 days (finding)|
  • 1373208000 |Baby premature 26 weeks to 27 weeks and 6 days (finding)|
  • 1373210003 |Baby premature 32 weeks to 35 weeks and 6 days (finding)|
• Concepts Inactivated:
  • 395507008|Premature infant (finding)|
  • 771507004 |Moderate to late prematurity of infant (disorder)|
  • 276658003 |Extreme immaturity (disorder)|
  • 268868001 |Born very premature (disorder)| 

2.5. Procedure

2.5.1. Radiographic Imaging

Work is progressing for this content tracker for information please see the informational briefing note here. 

For the September 2025 release a review of 315294004|Contrast enema (procedure)| and descendants has been undertaken. Subtypes that do not specify an imaging modality/align with the editorial guidance have been reviewed for inactivation and replaced by an imaging specific procedure concept.

2.6. Event

2.6.1. Inactivation of 'Death or Significant Injury' Related Concepts

A review has been undertaken for content of the type 370927008|Death or significant injury of a patient or staff member resulting from a physical assault (i.e., battery) that occurs within or on the grounds of the healthcare facility (event)|.

These concepts are classification-derived taken verbatim from the US Joint Commission and the National Quality Forum (NQF) Serious Reportable Events list. As the designation of a “reportable event” is a jurisdiction-specific classification, such content is more appropriately housed within extensions. Furthermore, these concepts represent disjoint entities, which supports their inactivation on the grounds of being classification-derived.

Number of concepts edited (approx): 13

2.7. Pharmaceutical/Biologic Product

2.7.1. Update Prolonged Release Transdermal Patch

As of Q3 2025, approximately 50 published concepts for prolonged-release transdermal patch modeled using concentration strength normalized to per 1 hour have been inactivated and replaced with 42 new concepts using presentation strength, based on the labeled total amount delivered over time (e.g., /16 hours, /24 hours [usual manufacturer-documented period], or /72 hours), in alignment with product SPCs and international editorial policy.

12 opioid patches (e.g., fentanyl, buprenorphine) are an exception and retain the /1 hour expression, consistent with manufacturer documentation and regulatory standards. This reflects patient safety requirements for these strong, controlled substances.

These concepts have not been inactivated, as the descriptions remain unchanged, but have been remodeled to use presentation strength.

• Key changes:
  • Presentation strength now replaces concentration strength for all prolonged-release transdermal patch concepts.
  • The Has unit of presentation attribute with a value of Patch (unit of presentation) has been added to all concepts.
  • Units now reflect the duration, strength, and units as specified in the SPC.
  • A small number of duplicate concepts have been identified and inactivated.

Number of concepts edited (approx): 64

Concept inactivations: 53

2.8. Core Metadata

2.8.1. Inactivation of 715515008|LOINC - SNOMED CT Cooperation Project module (core metadata concept)|

715515008 |LOINC - SNOMED CT Cooperation Project module (core metadata concept)| has been inactivated with reason outdated. It was previously used when the “LOINC Term to SNOMED CT Expression Reference Set” was released in 2017 under this module. As this reference set is no longer maintained or released, 715515008 | LOINC - SNOMED CT Cooperation Project module (core metadata) is not needed.

Please see http://loincsnomed.org for current information about the LOINC Ontology which has been released as an Extension of SNOMED CT.

2.9. Collaboration/Harmonization Agreements

2.9.1. Convergent Medical Terminology (CMT)

254 new concepts have been added for the September 2025 release. Key topic areas are musculoskeletal disorders, injury disorders, device complications and computed tomography procedures.

2.9.2. 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. 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.

2.9.3. 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 

2.9.4. 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.

2.10. Internal Quality Improvement

2.10.1. Machine Readable Concept Model (MRCM) Changes

There has been one change for MRCM in the September 2025 International Edition:

• Inactivation of Surgical Domain in MRCM
  • The attribute 180593004 |Surgical approach (qualifier value)| has been inactivated and replaced by 116688005 |Procedure approach (attribute)|. There is no attribute that is specific to the surgical procedures anymore. The domain has been inactivated in the MRCM, the entries have been inactivated in the RF2 refset release file. These changes should not have any impact on existing concepts and modeling.

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

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

2.10.2. 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.

2.11. SNOMED CT derived products

2.11.1. 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 hosted here https://confluence.ihtsdotools.org/display/DOCICD10.

2.11.2. 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#/).

Mapped content for September 2025 release

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

This includes:

• Addition of 816 new mapped concepts

• Updates to 134 existing mapped concepts
• Retirement of 99 mapped concepts

The SNOMED CT to ICD-O morphology map has zero (0) additions 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.

2.11.3. 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.

3. Technical notes

3.1. 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:

3.2. 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:

3.3. Technical updates

3.3.1. 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.

3.3.2.  Proposal to increase the maximum length of Description Types

Please find below the link to the recent announcement on the proposal to increase the limit of characters allowed in Descriptions:

• https://confluence.ihtsdotools.org/pages/viewpage.action?pageId=238158325

A community consultation was launched to solicit feedback on a 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, it could 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 which details the proposed change, its potential benefits, the feedback process and timelines, and the issues that may need to be considered in such an update:

• https://confluence.ihtsdotools.org/mag/community-consultations/snomed-international-proposal-to-increase-description-length-limit
• https://www.snomed.org/news/blog%3A-snomed-international-seeks-community-feedback-on-proposed-description-character-limit-increase

As always, SNOMED International greatly appreciated all feedback provided before the deadline (which was Dec 31, 2024).  A summary of the feedback will be collated and disseminated in 2025, alongside a plan for the transition.

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

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