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 2023 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 2023 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 2023 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.

1.5. Important Information

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 2023 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 the next stage has been implemented for subsequent releases including September 2023. 

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 for 399963005|Abrasion (disorder)| and Subtypes

The descriptions and/or finding site for subtypes of 399963005|Abrasion (disorder)| have been reviewed for alignment and remodeled where required. 

While many medical definitions refer to abrasions as superficial injuries of the skin and subcutaneous structures, the term is also used in dentistry to define superficial excoriations of teeth and can be used for other integumentary structures such as finger and toe nails.

Where the abrasion concept refers to the skin this has been specified in the FSN. The content has been updated to include this in the FSN and preferred term. Where the abrasion refers to a structure such as tooth, these concepts have been reviewed to ensure alignment between FSN and finding site.

2.2.2. Update for Concepts Using 'Caused by'

Clinical finding concepts containing "Caused by" in their FSN have been reviewed and updated according to the editorial guidelines related to causation here. The main focus of the review has been the following category of concepts:

• Concepts containing "Caused by" in their FSN that have a synonym (including PT), which contains “Due to”
• Concepts where FSN contains "Caused by" and "Due to"

Additional content updates have been made, for example:

• Concepts that do not contain “Caused by” or “Due to” in their FSN, but contain one of these terms as their preferred terms
• Concepts containing “Due “to in their FSN that have a preferred term which contains “Caused by”.

2.2.3. Review Hierarchy 240196003|Bone necrosis (disorder)|

Avascular necrosis of bone and aseptic necrosis of bone are considered synonymous with osteonecrosis. A review of existing content has been undertaken please see Fast track document

Eleven duplicate concepts have been inactivated. Approximately 100 concepts have had an update to either the model or descriptions or both.

For further information please see this briefing note.

2.2.4.  Review "Chronic respiratory disease in perinatal period" as a Chronic Condition

20322005|Chronic respiratory disease in perinatal period (disorder)| has been inactivated with reason classification derived component and replaced by new concept Respiratory disease originating in perinatal period (disorder). This update completes the content tracker.

2.2.5. Inactivation of "Did not attend X" or "Attended X" Clinical Finding Concepts

Approximately 30 "did not attend X" or "attended X" findings concepts, e.g., 390923003 |Did not attend cardiac clinic (finding)|, have been inactivated as they are administrative concepts.

Approximately 20 "did not attend X" or "attended X" situation concepts, e.g., 310352003 |Mammography not attended (situation)|, have been inactivated as they are out of scope for this hierarchy.

2.2.6. Measurement Findings

Six false positive and false negative measurement findings, e.g., 274684006 |False-positive serological test for syphilis (finding)|, have been inactivated with reason of Nonconformance to editorial policy.

2.3. Body Structure 

2.3.1. 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.  Procedure

2.4.1. Arthroplasty Conversion Procedures 

Arthroplasty conversion procedures have been remodeled to remove their association as revision procedures.

2.4.2.  Update Subtypes of 14766002 |Aspiration (procedure)

Subtypes of 14766002 |Aspiration (procedure)| have been remodeled with consistent use of 706681000 |Aspiration needle (physical object)| as the TARGET VALUE for the 424226004 |Using device (attribute)| attribute.

2.5. Clinical Finding

2.5.1. Abuse

Improvements has been made in the area of abuse in the Clinical Finding hierarchy. Further work on abuse content is planned.

2.6. Medicinal Product

2.6.1. Addition of Anti-Infective Clinical Drug Concepts 

The Drug Content Analysis Project (DCAP) was launched in September 2022 to identify clinical drug concepts that are published in participating National Release Center extensions and that are eligible for promotion to the International Edition (supported by appropriate references to authoritative source material).

Concepts that are already published in the Norwegian drug extension have been reviewed by multiple countries participating in the group and content eligible for promotion to the International Edition of SNOMED CT has been identified.

Approximately 100 concepts have been promoted to the International Edition and corresponding concepts for Medicinal Product (MP) 'containing only', and Medicinal Product Form (MPF) 'containing only' promoted from the Norwegian extension if missing. MP 'containing' concepts have been created in the International Edition as required.

2.6.2. Clinical Drugs Modeled with Dose Form 421366001 |Tablet for conventional release oral suspension (dose form)|

The dose form 421366001 |Tablet for conventional release oral suspension (dose form)| has been updated with the new Preferred Term 'Dispersible oral tablet'. This aligns with the EDQM standard.

37 clinical drugs that are defined with a dose form of 421366001 |Tablet for conventional release oral suspension (dose form)| have a new Preferred Term created for 'dispersible oral tablet' and the existing Preferred Term has been made a synonym. 

2.7. Substance

2.7.1. New Subtypes of 1155866009 |Messenger ribonucleic acid of severe acute respiratory syndrome coronavirus 2 encoding spike protein (substance)|

New subtypes have been added to 1155866009 |Messenger ribonucleic acid of severe acute respiratory syndrome coronavirus 2 encoding spike protein (substance)| including:

• "SARS-CoV-2 mRNA encoding B lineage spike protein" (i.e. "SARS-CoV-2 mRNA encoding original strain spike protein")
• Severe acute respiratory syndrome coronavirus 2 mRNA encoding BA.1 lineage spike protein
• Severe acute respiratory syndrome coronavirus 2 mRNA encoding BA.4/BA.5 lineage spike protein

These concepts have been created to meet the requirement for creation of bivalent vaccines (usually containing original strain + an omicron variant). In addition, creation of "SARS-CoV-2 mRNA encoding original strain spike protein" will allow for accurately representing monovalent vaccines containing "SARS-CoV-2 mRNA encoding B lineage spike protein" (original strain)."

2.8. Collaboration/Harmonization Agreements

2.8.1. Convergent Medical Terminology (CMT)

154 new concepts have been added for the September 2023 release. These are predominately oncology disorder concepts.

2.8.2. Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), content development is ongoing for rare disease concepts in SNOMED CT. Content in scope for this project is published in the annual update of the SNOMED CT to Orphanet Maps.

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

2.8.3. 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 

2.8.4. 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)|.

Eight new focal anatomical seizure concepts have been added for the September 2023 release.

Further information about the changes is available here. 

2.8.5. Gravity Project

Work is ongoing for this content area.

2.9. Internal Quality Improvement

2.9.1. Machine Readable Concept Model (MRCM) Changes

The following change has been made to the MRCM for the September 2023 International Edition:

• 1142142004 |Has pack size (attribute)| is an attribute that is used for modeling real clinical drugs in a national extension (not for use in the International Edition of SNOMED CT). The current MRCM prevents national extensions from using a decimal to define a pack size (for example, a 3.5 milliliter bottle) as it limits the attribute range to whole integers only. The MRCM has been changed for Has pack size (attribute)| from Integer to Decimal.

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

Please see early visibility for future planned changes to MRCM.

2.10. SNOMED CT derived products

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

The ICD-10 Mapping Technical Guide (including exemplars) is hosted here https://confluence.ihtsdotools.org/display/DOCICD10

2.10.2. 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 September 2023

The map provided for the September 2023 International Edition has been updated, and now represents a complete map from SNOMED CT International Edition to ICD-10 2016 version.

• 342 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has no additional concepts 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 mapping@snomed.org

2.10.2. 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. Configuration file in the RF2 package, containing Release Metadata 

A configuration file ("release_package_information.json") is now included in the International Edition, containing metadata about the Release package itself, including:

• effectiveTime
  

• previouslyPublishedPackage

• languageRefset(s)

• licenceStatement

The metadata will be continually refined going forward, so if you have any ideas about useful information to include please send them to release@snomed.org, along with a business case explaining how the information would benefit stakeholders.  Please be aware that use cases will then be assessed by SNOMED International, and new metadata will only be added for strong business cases.  

3.3.3. Changes to the Identifier file format

In line with the proposals documented here:  https://confluence.ihtsdotools.org/mag/snomed-international-proposal-to-change-the-rf2-identifier-file-specification - the International Edition Release will from now on include the following changes to the format of the Identifier files:

• < identifierSchemeId    alternateIdentifier    effectiveTime    active    moduleId    referencedComponentId           ...to
• > alternateIdentifier    effectiveTime    active    moduleId    identifierSchemeId    referencedComponentId

These improvements are introduced in the September 2023 International Edition release, and will be used in all future International Edition releases until further notice.

3.3.4. Early visibility of impending changes in the upcoming 2023 Monthly International Edition releases

Please see the early visibility page below for details of forthcoming changes:

• https://confluence.ihtsdotools.org/display/RMT/2023+Early+Visibility+Release+Notifications