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© 2024 International Health Terminology Standards Development Organisation.  All rights reserved.  SNOMED CT® was originally created by the College of American Pathologists.

This document forms part of the International Edition release of SNOMED CT® distributed by International Health Terminology Standards Development Organisation, trading as SNOMED International, and is subject to the SNOMED CT® Affiliate License, details of which may be found at

No part of this document may be reproduced or transmitted in any form or by any means, or stored in any kind of retrieval system, except by an Affiliate of SNOMED International in accordance with the SNOMED CT® Affiliate License. Any modification of this document (including without limitation the removal or modification of this notice) is prohibited without the express written permission of SNOMED International.

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Page At A Glance

Table Of Contents

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 April 2022 release of SNOMED Clinical Terms® (SCT) International Release.

It also includes technical 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 April 2022 International release.

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 during the release.

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 April 2022 International release.

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

1.5. Changes to the International Edition Release Schedule


SNOMED International have transitioned to a more frequent (monthly) delivery schedule for the International Edition of SNOMED CT.  The move towards more frequent releases of SNOMED CT will realise several benefits, including:

  • The potential to be able to get content changes into the terminology in a shorter time frame.
  • The fostering of better interoperability, as a result of entities being able to consume release content that is more aligned with other organizations.
  • The prevention of circular dependencies that occur in longer projects, due to the move towards smaller, more manageable authoring projects.
  • More automated validation services, as a result of the inherent removal of the Alpha/Beta stages in the Release cycle.

Whilst most users will continue unaffected (as they can simply continue to download the releases every 6 months as always), this transition necessarily involved a few changes to process/packages:

  • The Member Release period is no longer be required within the new rapid monthly release schedules.  If you would like to continue assisting in the validation efforts of SNOMED CT there are other ways in which you can help - please contact to find out more.
  • Delta files have been removed from the release package - a Delta Generation service will be provided for those who need it.   The Delta Generation Tool allows users to create their own Delta between two fixed release dates - you can find it here:
  • The ICD-0/ICD-10 Maps will continue to be published in each Monthly International Edition release package (in line with that month's content) for the foreseeable future, unless we experience issues with the new process in Production, and they need to be removed at a later date.

NOTE:  SNOMED International worked closely with Members over the past couple of years to better understand the impact of the proposed model, and have incorporated feedback into the new processes.  This was designed to prevent any adverse impact to users, however if you have any further questions or concerns please see the FAQ's here, or contact us on

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 April 2022 International Release 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 Guidemapping guidance for ICD-10 can be found here

2.2. COVID-19

Content relating to COVID-19 can be viewed here SNOMED CT COVID-19 Related Content

Any concepts in scope for the SNOMED CT to ICD-10 mapping have been mapped and adhere to the World Health Organization current guidelines.

2.3. Concept Inactivation Changes

Please see new editorial guidance for changes to inactivation values here

2.4. Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 release the next stage has been implemented for subsequent releases including April 2022. 

Quality improvement tasks were 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 was carried out to accurately reflect current clinical knowledge and ensure the semantic reliability of descriptions associated with a concept.

Information about the project can be found here 

2.5. Body Structure 

Progress of the Anatomy Model and Plan for Further Demonstration Release

There are approximately 35,000 anatomy concepts to be modeled by different types of 'part of' relationships. The new model will enable the automatic generation of hierarchies to further improve content quality and consistency. The integumentary system (about 2000 concepts) has been modeled. The modeling of the musculoskeletal system (about 10,000 concepts) is currently in progress.

The concept model requires tooling enhancements to support nested expressions and the option of inferred relationships for transitive and reflexive attributes. We will inform the community of the schedule for the demo release when the tooling and content are ready. The demo release will help us to gather feedback to evaluate potential impact and options for future release.

2.5.1. Description Changes for Tendon Sheath

A concept 'tendon sheath of a region' represents a tendon sheath structure within a body region. For example, 'structure of tendon sheath of finger' represents tendon sheath structures that are either entire tendon sheath or tendon sheath parts within the finger region. 

FSN and preferred term have been updated to use 'within' rather than 'of' to align with this.  Further information is available here

2.5.2. New Subtypes of 33840008 |Structure of periosteum (body structure)

New subtypes of 33840008 |Structure of periosteum (body structure)| were added in order to facilitate remodeling in the hierarchy 41910004 |Periostitis (disorder)|.

2.5.3. SEP and Laterality Anatomy Reference Sets

Updated and validated release file for the lateralizable body structure reference set. 

Updated and validated release files for the SEP refsets.

The updates of SEP refsets and laterality refset are enhanced by new validation rules and automations as part of the authoring process.

2.6. Clinical Finding

NOTE: 'Co-occurrent and due to' pattern:

During the implementation of the new Description Logic features, a conflict was uncovered between the modeling of 'Co-occurrent and due to' and General Concept Inclusions (GCIs). This has resulted in the need to reconsider the modeling of "Co-occurrent and due to' and update the Editorial Guide for this area.

The Editorial Guide and all concepts that are currently modeled as 'Co-occurrent and due to' will be updated over future release cycles.

2.6.1. Inactivation of 116223007|Complication (disorder)

After consultation with the SNOMED Editorial Advisory Group, the ambiguous primitive concept 116223007 |Complication (disorder)| has been inactivated. Subtypes of this concept continue to classify under their other existing inferred parents except for a few high level grouper concepts that now classify directly under 64572001 |Disease (disorder)|.

2.6.2. Inactivation of Subtypes of 717234006 |Allergy to animal protein (finding)

Inactivated subtypes of 717234006 |Allergy to animal protein (finding)| sub-hierarchy that represent allergy to "animal part" and replaced by concepts representing “Allergy to X animal protein”.

2.6.3. Remodeling of 234467004 |Thrombophilia (disorder)| and Subtypes

The 55 subtypes of 234467004 |Thrombophilia (disorder)| have been remodeled, adding role groups and appropriate new parents where required, and including the inactivation of a small number of concepts, to ensure the correct classification within the hierarchy for acquired thrombophilia and hereditary thrombophilia.

2.6.4. Remodeling of 41910004 |Periostitis (disorder) and Subtypes

Remodeled the area of 41910004 |Periostitis (disorder)| with new subtypes of 33840008 |Structure of periosteum (body structure)|.

2.6.5. Relapsing and Recurrent Clinical Course

Clinical course has been updated for a number of disorder concepts which reference relapsing or recurrent in the descriptions. 

NOTE: Disorder X without Disorder Y

The vast majority of existing X without Y concepts originated from ICD-9 with the specific meaning of "X disorder without mention of Y disorder".  As the phraseology indicates a lack of data about disorder Y as opposed to a specific exclusion, this type of concept has not been included in ICD-10, nor proposed for ICD-11, except in the case of "Traumatic brain injury without open intracranial wound".  

Addition of new X without Y concepts may only be made under the following conditions:

  1. The request for new content must be accompanied by a rationale as to the difference between "X disorder without Y disorder" and "X disorder."

  2. Approval for addition is given by the Chief Terminologist.

For the most part, existing X without Y concepts will be inactivated as AMBIGUOUS with a historical MAY BE relationship to "X disorder".  Exceptions to inactivation will be made on a case-by-case basis.

2.7. Procedure

2.7.1. Remodeling of 74799003 |Flap graft (procedure)| and 256683004 |Flap (substance)| and Subtypes

Remodeling has been completed on the area of flap procedure which were previously a subtype of 74799003 Flap graft (procedure).

74799003 Flap graft (procedure) has been inactivated and replaced with 1202017008 |Surgical procedure using flap (procedure)|. The improvements have included development of a new model and extensive remodeling of this area of content.

For the April 2022 release the final work has been completed with improvements to the sub-hierarchy of 256683004 |Flap (substance)| (including planned inactivations). The redesign has involved adding new qualifier values as subtypes of 360032005 |Flap reconstruction - action (qualifier value)|. Editorial Guidance outlining the new model has been drafted and now added for publication.

2.7.2. Update Descriptions for Transcatheter Aortic Valve Implantation (TAVI) and Transcatheter Aortic Valve Replacement (TAVR)

Transcatheter aortic valve implantation (TAVI) and transcatheter aortic valve replacement (TAVR) are synonymous.

  • 'Transcatheter aortic valve implantation' is now the description terming for the FSN and PT for these procedures, with the addition of TAVI acronym based synonym(s).

  • For the International edition of SNOMED CT we have retained transcatheter aortic valve replacement as an acceptable synonym for transcatheter aortic valve implantation, with the inclusion of TAVR acronym based synonym(s).

Therefore, 725351001 |Transcatheter aortic valve replacement (procedure)| has been inactivated as duplicate to 773996000 |Transcatheter aortic valve implantation (procedure)| and the description 'Transcatheter aortic valve replacement' and the TAVR acronym added as a synonyms to 773996000 |Transcatheter aortic valve implantation (procedure)|.

Similarly, 1184601001 |Revision of transcatheter aortic valve replacement (procedure)| has been inactivated as duplicate to 1184601001 |Revision of transcatheter aortic valve implantation (procedure)| and 'replacement' descriptions added as synonyms as described above.

2.7.3. Inactivation of Endoscopy Procedures Stating Therapeutic or Diagnostic Intent

Following consultation with the community of practice, work has commenced to inactivate endoscopy content stating intent as diagnostic or therapeutic. The inactivation reason is Non-conformance to editorial policy and REPLACED BY an intent agnostic concept.

2.7.4. Morphology Update for Cataract Procedures

Cataract procedure concepts have had the value for 363700003 |Direct morphology (attribute)| updated to 128305008 |Abnormally opaque structure (morphologic abnormality)| in line with the previous work done on cataract disorders. Please see here for further details.

2.7.5. Remodel 10942006 |Plication (procedure)

10942006 |Plication (procedure)| and subtypes underwent structural quality improvement including addition of intermediate primitives and stated attribute-value pairs, where applicable.

2.7.6. Inactivation of 28289002 |Injection of therapeutic agent (procedure)|

28289002 |Injection of therapeutic agent (procedure)| was inactivated due to the ambiguous nature of 'therapeutic agent'. The subtypes were either treated similarly or remodeled to the appropriate place in the hierarchy.

2.8. Situation With Explicit Context

2.8.1. Inactivation of Administrative Concepts

The following situation hierarchy concepts have been inactivated due to the lack of unambiguous meaning and reproducible use case among healthcare systems:

  • 394827008 |Personal administration (situation)|
  • 394824001 |Private prescription (situation)|
  • 182819002 |Replacement therapy (situation)|
  • 394822002 |Prescription types (situation)|
  • 394829006 |Past medication (situation)|
  • 182817000 |Drug prescription (situation)|
  • 703955006 |Prescription telephone order (situation)|

2.9. Qualifier Value

NOTE: Planned Inactivation of 260299005 |Number (qualifier value)| and Descendants

Following the deployment of the concrete domain functionality in SNOMED CT, concepts in the 260299005 |Number (qualifier value)| hierarchy are no longer necessary and plans have been made for their inactivation. To provide adequate time for any national extension or implementation affected by this change, concepts in the 260299005 |Number (qualifier value)| hierarchy will be inactivated in the January 2023 International Release.

Concepts will be inactivated with reason “Non-conformance to editorial policy” and no historical relationship or replacement concept will be provided.


118586006 |Ratio (property) (qualifier value)| and descendants have been relocated to 118598001 |Property (qualifier value)| hierarchy.

272070003 |Ordinal number (qualifier value)| and descendants have been relocated to 362981000 |Qualifier value (qualifier value)| hierarchy.

A briefing note will also be distributed to selected Advisory and Project Groups.

Please contact with any inquiries.

2.10. Substance

Release plans, Substance hierarchy

For further details on the planned changes in this area, please refer to Substance Project

2.11. Pharmaceutical/Biological Product

Drug model project

For further details on the planned changes in this area, please refer to the Drugs Project

2.12. Physical Object

Physical Object

For further details on the planned changes in this area, please refer to Devices Project

2.13. Collaboration/Harmonization Agreements

2.13.1. Convergent Medical Terminology (CMT)

152 CMT concepts have been added along with new supporting anatomy content where required.

2.13.2. Orphanet

Working in collaboration with Orphanet (, creation of new concepts for the original set of prioritized rare diseases has been completed. All of the concepts added for the Orphanet project have been mapped to ICD-10.

The Production release of the SNOMED CT to Orphanet Simple Map was published in October 2021. Work is now underway to add further content to the SNOMED CT to Orphanet Simple Map for future releases starting with the next Production release in October 2022.

2.13.3. ICD-11 Update

The April 2022 release has seen continued addition of content for this project.

2.13.4. 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 

2.14. Internal Quality Improvement

2.14.1. Machine Readable Concept Model (MRCM) Changes

Details for forthcoming changes can be reviewed here 

NOTE: Advance Notice of Cardinality Changes Scheduled for July 2022 Release

All historical content issues where two or more finding sites were included in a single role group have been resolved in the International release as part of the QI project.

There are two MRCM rules for finding site to accommodate the historical content. One MRCM is applicable to all content, it allows more than one finding site in a role group. The other MRCM is only applicable for 'All new precoordinated SNOMED CT content'.

The existing MRCM rules will be updated to only allow at most one finding site in a role group from the July 2022 release.

This early notice is intended to provide additional time for content updates in national extensions. 

Please contact with any inquiries.

2.15. SNOMED CT derived products

2.15.1. 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 release 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 |ICD-10 complex map reference set (foundation metadata concept)|.

2.15.2. 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 limited to subtypes of 404684003 |clinical finding|, 272379006 |event| and 243796009 |situation with explicit context|.  The target classification codes are ICD-10 2016 release. 

Mapped content for April 2022

The map provided for the April 2022 release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

  •  356 newly authored concepts have been added and mapped.

  • The SNOMED to ICD-O (morphology) map has 1 additional concept added as a result of the ICD-O 3.2 review or added due to CRS requests.

We would welcome feedback on any issues that users of the map may detect when using the map. Issues should be submitted via

2.15.3. Technical Guide Exemplars

The Technical Guide Exemplars document has now been moved from the International Edition release package to a Confluence page.  This page can be found as part of the ICD-10 Mapping Technical Guide (see Appendix B), which is hosted here:

2.15.4. 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:

Please contact SNOMED International at 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:

Key Summary Description

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:

Key Summary Description Resolved

3.3. Technical updates

3.3.1. RF2 package format

For future reference, the RF2 package convention dictates that it contains all relevant files, regardless of whether or not there is content to be included in each particular release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and also files that are intentionally left blank (including only a header record).  The reason that these files are not removed from the package is to draw a clear distinction between files that:

  • have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in this or future releases, and 

  • happen to contain no data in this particular release (and are therefore included in the package but left blank, with only a header record), but are still relevant to RF2, and could therefore potentially contain data in future releases.

This allows users to easily distinguish between files that have purposefully been removed or not, as otherwise if files in option 2 above were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.

Configuration file in the RF2 package, containing Release Metadata 

A new file has been included since the July 2020 International Edition, containing metadata about the Release package itself.  This has been created in conjunction with feedback from the community, and as such initially contains the following fields:

  • effectiveTime

  • previouslyPublishedPackage
  • languageRefset(s)

  • licenceStatement

The file is in .JSON format, to ensure that it is both machine-readable and human-readable, and is named "release_package_information.json".

The metadata will be extended and refined going forward, in order to ensure that it contains the most useful information possible. If you have any ideas about any other useful information to include, please send them to, along with a business case explaining how the information would benefit stakeholders.  Please be aware that this use case will then be assessed by SNOMED International, and the new metadata will only be included in the configuration file if the business case is strong enough.  

3.3.2. New Association References

In order to support the Content changes above in section 2.3. Concept Inactivation Changes, the following Association Reference set members have been added to the International Edition from the April 2022 release onwards:

  • 1186921001|POSSIBLY REPLACED BY association reference set
  • 1186924009|PARTIALLY EQUIVALENT TO association reference set

3.3.3. Early visibility of impending changes in the upcoming 2022 Monthly International Edition releases

Please see the following page for details of all upcoming changes planned for 2022: 

All links provide information that is correct and current at the time of this Release.  Updated versions may be available at a later date, but if so these will need to be requested from the relevant SNOMED International teams.

NOTE:  To access any of the links in the pdf document, please visit the Release Notes @


Final Version






Rory DavidsonApproved


Monica HarryApproved


Kelly KuruApproved

Draft Amendment History







Andrew Atkinson

First draft for review and comment



Maria BraithwaiteInitial content updates


Maria BraithwaiteFinal Content changes


Andrew Atkinson 

Final Production changes

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