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 March 2026 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 March 2026 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 March 2026 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 March 2026 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 Assurance

Update Historical Association for ‘On examination’ and ‘Complaining of’ Inactive Concepts

The reason for inactivation and historical association values for the ‘on examination’ and ‘complaining of’ concepts have been reviewed and updated as required.

The main focus of this work were the concepts with the 'moved elsewhere' reason for inactivation as these concepts did not have a historical association to a base concept. In a significant number of cases there were one or more 'like' concepts that had previously been inactivated. Given this, the aim was to ensure the concepts being updated were given the same inactivation reason and historical association values as the “like’ concepts.

In addition, when the initial inactivation work was undertaken the default reason for inactivation used was 'ambiguous', unless guidance required otherwise e.g., the concept was classification derived. Much of the content was not actually ambiguous, rather out of scope, given that the default reason for inactivation has been updated to 'nonconformance to editorial policy'.

Please note, this work was primarily undertaken using automated processes.

Review Hierarchy 365853002|Imaging finding (finding)|

365853002|Imaging finding (finding)| and its 852 descendants have been reviewed. A finding site has been added to the concepts where appropriate (and not currently stated) so that the concepts classify as a subtype of the ‘finding of X anatomic structure’ concept where published.

For example:

• 441914009 |Imaging of head abnormal (finding)| - finding site 69536005 |Head structure (body structure)| added to classify as a subtype of 406122000 |Head finding (finding)|.

These changes have improved consistency and subsumption of the content as each concept classifies under the appropriate ‘Finding of body structure X’ parent where one is published.

The changes complete this Content Tracker.

Review Otitis and Descendants

A review of 43275000 |Otitis (disorder)| and 298 descendants has been undertaken.

The changes include:

• Update to model to ensure consistency, correct classification and to sufficiently define concepts where possible

• Review finding site and morphology for 65363002 |Otitis media (disorder)| and descendants

• Review groupers e.g. 270490007 |Acute otitis media with effusion (disorder)|

• Inactivation of duplicate or ambiguous concepts

• Inactivation of non-synonymous or erroneous synonyms

The changes complete this Content Tracker.

Body Structure 

Update Stab Wound and Puncture

The hierarchical relationship between 42577003|Stab wound (morphologic abnormality)| and 11639007|Puncture (morphologic abnormality)| has been revised.

42577003 |Stab wound (morphologic abnormality)| is now a descendant of 11639007 |Puncture (morphologic abnormality)|. New text definitions have been added to clarify that while both represent penetrating injuries, a stab wound specifically implies a cutting action and depth. Consequently, disorders modeled with a stab wound morphology now classify as subtypes of puncture wounds, while maintaining their existing classification as open wounds.

Number of concepts edited (approx): 65

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.

Clinical Finding

Update Wound Dehiscence and Wound Disruption

Text definitions have been added to the following morphologic abnormality concepts to clarify intended usage and support consistent modeling:

• 410723003 |Wound dehiscence (morphologic abnormality)| - Reserved for separation or breakdown of a wound that has been intentionally closed by a healthcare professional, including intentionally repaired traumatic wounds.

• 609345009 |Dehiscence surgical incision wound (morphologic abnormality)| - Separation or breakdown of a surgical incision wound that has been surgically closed.

• 609348006 |Disrupted wound (morphologic abnormality)| - Separation or breakdown of a wound that is not attributable to failure of an intentional closure.

Although the term may be encountered in broader usage, dehiscence is most commonly used and preferred to describe breakdown of an intentional closure performed by a healthcare professional. As a result of these clarified definitions, 16 disorder concepts and approximately 10 procedure concepts have been remodeled to align with the updated guidance.

Number of concepts edited (approx): 30

Inactivation of 86569001 |Postpartum state (finding)| and Descendants

Concepts representing postpartum days lack a universally accepted definition that applies across all jurisdictions.  86569001|Postpartum state (finding)| and subtypes referring to days (e.g. 30118000|Postpartum period, 1 day (finding)|) have been inactivated and replaced with concepts that specify the time in hours. 

The following concepts have also been inactivated:

• 16538005|Early postpartum state (finding)|

• 42814007|Mid postpartum state (finding)|

• 56026007|Late postpartum state (finding)|

The meaning of these concepts varies based on the jurisdiction and context, often depending on whether a calendar-day or an elapsed-time convention is employed. For instance, "Day one" is subject to different interpretations; while the most common clinical understanding is the first 24 hours after birth, some settings or jurisdictions use "Postpartum Day 0" when the birth occurs later in the calendar day.

Substance

Update 768664009 |Amphotericin B phospholipid complex (substance)|

768664009 |Amphotericin B phospholipid complex (substance)| has been reactivated, 425953004 |Amphotericin B lipid complex (substance)| has been inactivated with reason ambiguous and a possible replacement of 425953004|Amphotericin B lipid complex (substance)| and 427544000 |Amphotericin B cholesteryl sulfate complex (substance)|.

Both are theoretically classified as lipid complexes of Amphotericin B. The FDA have classified Amphotericin B cholesteryl sulfate complex as a lipid complex even though the official name drops the lipid complex (unlike Abelcet, which retains it). Both are lipid complexes.

The changes will be replicated to the relative medicinal products and clinical drugs. The term 'Amphotericin B lipid complex' is used to describe the brand name drug product of Abelcet. However, the name is a misnomer, because the formulation is not that of lipids but of phospholipids. This change prompts the inactivation of related concept, 785130004 |Product containing precisely amphotericin B lipid complex 5 milligram/1 milliliter conventional release solution for injection (clinical drug)|. A replacement concept would need to be created, but this drug is not a solution for injection but a concentrate for dispersion for infusion. So, new concept |Amphotericin B phospholipid complex 5 mg/mL concentrate for dispersion for infusion| is its Possibly equivalent target.

Number of concepts edited (approx): 10

Inactivation of 418165002 |Herbal medicine agent (substance)|

418165002 |Herbal medicine agent (substance)| has been inactivated because it is a role, and its definition varies by country.

Collaboration/Harmonization Agreements

Convergent Medical Terminology (CMT)

25 new CMT disorder concepts have been added for the March 2026 release with a key focus on cardiovascular disorders, together with a small number of other finding and disorder concepts.

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 March 2026 International Edition.

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.

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 March 2026 release of the SNOMED CT International Edition to the ICD-10 WHO version 2016.

This includes:

Mapped content for March 2026 release

• Addition of 161 new mapped concepts

• Updates to 118 existing mapped concepts

• Retirement of 76 mapped concepts

The SNOMED CT to ICD-O morphology map has zero content changes 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.