Introduction

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.

Purpose

This document provides a summarized description of the content changes included in the October 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 October 2023 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 October 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.

Important Information

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 October 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.

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 October 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. 

 Remodel of Obstetric Procedures

Work has been undertaken to resolve the suboptimal concept model and classification for over 100 concepts that are related to procedures on gravid uterus.

The scope for this work was:

<< 71388002 |Procedure (procedure)| : << 363704007 |Procedure site (attribute)| = << 9258009 |Gravid uterus structure (body structure)|

The remodeling of obstetric procedures has been achieved by assigning two GCI axioms to "Obstetric procedure" and introducing the "occurrence" attribute for modeling detailed maternal perinatal period and pregnancy time period for its subconcepts. These updates have improved modeling consistency and addressed incomplete classification results. The total number of obstetric procedures has increased from 380 to over 560.

Key changes made were:

• The occurrence attribute is applied for remodeling procedures on gravid uterus. The new model utilizes occurrence in conjunction with procedure site of uterus.
• Added two GCI axioms for obstetric procedure to include procedures performed during pregnancy period or maternal postnatal period. Classification results are improved by fully defined obstetric procedure with specific methods, e.g. Obstetric ultrasonography, obstetric operation, etc.
• Obstetric ultrasound scan includes ultrasound of fetus, placental structures that are not parts of the uterus. Hence, it should not be a subconcept of ultrasound of gravid uterus.
• Fixed incomplete classification results of ultrasound scan of fetus. Ultrasound scan for fetal growth, presentation, and viability should be scans of fetus, but they were not. After the revision, 31 subconcepts have been identified.
• Fixed incorrect role group of occurrence on its own that are related gravid uterus.
• Inactivated injection of amnion procedure because it could be injection into amnion cavity or injection of amnion fluid into other body structures.
• Updated modeling of abortion procedures
• Obstetric action has only one subconcept delivery action. The obstetric action will be inactivated in a future release. Delivery procedure is defined by procedure and delivery action during pregnancy time period. The delivery could happen before or after the expected the due date.
• Applied occurrence to Cesarean section model
• Procedures for inverted uterus are refined by reposition of uterus by manual manipulation and surgical repairs that performed at maternal intrapartum or postnatal period. The inverted uterus is not always caused by obstetric reasons. Most of these procedures are not classified as obstetric procedures anymore.
• Updated the concept model for MRI of fetus and its subconcepts.

Add concepts: <procedure> during <event>

Work completed for content tracker IHTSDO-102 with associated new editorial guidance for 'Procedure during period of life'.

 Update for  T-cell Lymphoblastic Leukemia/Lymphoma concepts

Following a member request there has been an expert pathology review of T-cell lymphoblastic leukemia/lymphoma concepts. Those with outdated terming of precursor T-cell lymphoblastic leukemia /lymphoma that is no longer used have been changed as listed below.

New concept: 1287593005 |Early T-precursor lymphoblastic leukemia/lymphoma (disorder)|. Defined with new 1287594004 |Early T-precursor lymphoblastic lymphoma/leukemia (morphologic abnormality)|

• 703821009 |T lymphoblastic leukemia/lymphoma (morphologic abnormality)| - inactivated duplicate with historical association to 397348006 |T-lymphoblastic lymphoma/leukemia (morphologic abnormality)|.
• 277575008 |T-cell acute lymphoblastic leukemia (disorder)| updated to 277575008 |T-lymphoblastic leukemia (disorder)| with synonym Precursor T-cell lymphoblastic leukemia.
• 397348006 |Precursor T cell lymphoblastic leukemia/lymphoblastic lymphoma (morphologic abnormality)| updated to 397348006 |T-lymphoblastic lymphoma/leukemia (morphologic abnormality)| with synonym Precursor T cell lymphoblastic leukemia/lymphoblastic lymphoma.
• 128824003 |Precursor T-cell lymphoblastic leukemia (morphologic abnormality)| updated to new FSN 128824003 |T-lymphoblastic leukemia (morphologic abnormality)| with Precursor T-cell lymphoblastic leukemia as synonym.
• 420890002 |Precursor T cell lymphoblastic leukemia/lymphoblastic lymphoma (disorder)| updated to new FSN 420890002 |T-lymphoblastic leukemia/lymphoblastic lymphoma (disorder)| with Precursor T cell lymphoblastic leukemia/lymphoblastic lymphoma as synonym.
• 421246008 |Precursor T-cell lymphoblastic lymphoma (disorder)| to updated to new FSN 421246008 |T-lymphoblastic lymphoma (disorder)| with Precursor T-cell lymphoblastic lymphoma as synonym.
• 128808004 |Precursor T-cell lymphoblastic lymphoma (morphologic abnormality)| updated to new FSN 128808004 |T-lymphoblastic lymphoma (morphologic abnormality)| with synonym Precursor T-cell lymphoblastic lymphoma.

Body Structure 

Update for Anterior and Posterior Rami of Spinal Nerves

Content editing has been undertaken to rationalize the concepts relating to anterior and posterior rami of the spinal nerves. Classification derived content relating to the four upper ventral (anterior) rami has been inactivated.

 Update for Occipital Bone Structures

Occipital bone structures have been reorganized by the basilar, lateral and squamous regional parts.

Update for Choroid

The structures of the choroid have been rearranged into three regions and four layers. Changes were made to 35 concepts including the addition of new concepts and inactivation of ambiguous concepts.

Remodel for Acetabular Cartilage Complex

Acetabular cartilage complex and its relationships to articular cartilage, growth plate, and bone have been updated.

Inactivation of Left Eye/Right Eye

The anatomy concepts, eye and left/right eyes have been inactivated with reason ambiguous and replaced by eye region/proper and left/right eye region/proper. These inactivated concepts are subconcepts of eye proper. The replacements by the new eye proper concepts has no impact on classification results.

Update for Joints and Subregions of Foot

Resolved missing and incorrect relationships between the joints and the subregions of the foot, hindfoot, midfoot, and forefoot.

New concepts have been added for "Cuneocuboid joint" and "Subtalar joint complex". The complex subsumes "Subtalar joint" and "Talocalcaneonavicular joint".

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

Arthroplasty Conversion Procedures 

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

 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.

Clinical Finding

Inactivation of 308971001 |Payment for service status (finding)| and Descendants

This area of content originated from NHS Read codes and due to it's jurisdiction-specific and administrative nature falls outside the scope of the international edition as not related to direct clinical care or management of care. 70 concepts have been inactivated without replacement following member request and consultation with the community of practice. For further information please see the briefing note.

Medicinal Product

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.

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. 

Substance

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

Update for Synovial Cyst

Synovial popliteal cyst is the most common cyst of knee. However, there are other cysts of knee. New concepts for synovial popliteal cyst have been created and removed synonyms from cyst of knee.

Procedure

Update for 129348007 |Z-plasty - action (qualifier value)|

129348007 |Z-plasty - action (qualifier value)| has been updated with a new FSN of 129348007 |Local flap reconstruction by Z-plasty - action (qualifier value)| and a new parent of 1193841002 |Local flap reconstruction - action (qualifier value)|

13 procedure concepts referring to Z-plasty have been remodeled to match the template model for flap procedures. One concept 177414001 |Z plasty to head or neck (procedure)| has been inactivated and replaced with 2 separate concepts.

Situation with Explicit Context

Update Hierarchy 271903000|History of pregnancy (situation)|

Description changes, concept inactivation, update to model, addition of subtypes to the hierarchy 271903000|History of pregnancy (situation)|.  Approximately 80 concepts have been updated.

The following concepts have been inactivated:

• 161811009|History of perinatal fetal loss (situation)|
• 726626004|History of neonatal death (situation)|

Replacement concepts have been added:

• 1290167007 |Past pregnancy history of neonatal death (situation)|
• 1290171005 |Past pregnancy history of late neonatal death (situation)|
• 1290170006 |Past pregnancy history of early neonatal death (situation)|
• 1290143004 |Past pregnancy history of perinatal death (situation)|
• 1290142009 |Family history of perinatal death (situation)|
• 1290168002 |Family history of neonatal death (situation)|

Description changes: Update FSN and PT to "Past pregnancy history of X" to state the history a past pregnancy finding or procedure explicit in the FSN and preferred term. Pregnancy related concepts in situation hierarchy have been remodeled to subsume under 271903000|History of pregnancy (situation)|.

Inactivation of Content 'X-Result Not Back'

Four concepts of the type "X result not back (situation)," e.g., 168709001 |Soft tissue X-ray result not back (situation)|, have been inactivated as they are out of scope for the international edition.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)."

Collaboration/Harmonization Agreements

Convergent Medical Terminology (CMT)

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

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.

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)|.

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

Further information about the changes is available here. 

Gravity Project

Work is ongoing for this content area.

Internal Quality Improvement

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.

SNOMED CT derived products

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 October 2023

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

• 472 newly authored concepts have been added and mapped.

• The SNOMED to ICD-O (morphology) map has 7 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

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.

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.  

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