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 January 2020 release of SNOMED Clinical Terms^® (SCT) International Release.

It also includes technical notes detailing the known issues which have been identified and agreed to be released. These are content or technical issues where the root cause is understood, and the fix has been discussed and agreed, but has yet to be implemented.

The SNOMED International Release Notes are available alongside the January 2020 International Edition 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 January 2020 International Edition release.

2. Content Development Activity

2.1. Summary

Continuous quality improvement and enhancement of existing content is an ongoing process by SNOMED International for every release. The January 2020 International Release has seen a continuation of the work driven by contributions from: Kaiser Permanente 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 in progress for new and enhanced content through project driven initiatives which are also summarized below.  Also included as work items for every release are various updates to SNOMED CT derived maps such as ICD-10 and ICD-O and details are also 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 at this link https://confluence.ihtsdotools.org/display/DOCICD10

2.2. Content Quality Improvement

2.2.1. Body structure 

New body structure concepts: 467

The new anatomy concept model implements the enhanced Description Logic features, e.g. reflexive and transitive properties, additional axioms for consistent logical modeling. The inferred IS_A relationships from the OWL anatomy ontology have been reviewed and the changes have been implemented in production. Potential impact to other hierarchies for example clinical finding, procedure, observable entity, situation with explicit context, were also reviewed as part of the project. Revision of hierarchical relationships for all body systems has been completed. The changes in the 2020 January release include:

Changes to hierarchical relationships in body structures:
• Nervous system: 1,303
• Respiratory system: 402
• Hematological system: 157
• Immune system: 132
• Lymphoreticular system: 144
• Integumentary system: 513
• Special senses organ system: 413
• Endocrine system: 88

Review of potential impact and most issues addressed in other hierarchies for example disorder, procedure, by body system: 

• Nervous system: 5,714
• Respiratory system: 2,264
• Hematological system: 844
• Immune system: 772
• Lymphoreticular system: 696
• Integumentary system: 5,970
• Special senses organ system: 5,080
• Endocrine system: 1,123

2.2.1.1. Quality Improvement in the Body Structure Hierarchy

Nervous system:

Hierarchical relationships and concepts that are descendants of 25087005 |Structure of nervous system (body structure)| have been reviewed and improved. The appraisal included rationalization of the peripheral nerves and cranial nerves to ensure that a branch of a specified nerve is not subordinate to the nerve from which it originates, but has an IS_A relationship to the regional nerve structure that covers the entire anatomical boundaries of every branch of that nerve. Any relationships that did not fulfil this rule have been corrected.

It has been identified that the use of the term ‘cerebrum’ is ambiguous within clinical terminology historically: sometimes referring to the brain as a whole, and on other occasions referring to the more limited meaning of the cerebral hemispheres. In order to clarify the semantics of ‘cerebrum’, the concept 83678007 |Structure of cerebrum (body structure)| location and definition has been elucidated using the following statement: ‘The cerebrum is the regional structure of the brain, which is the adult equivalent of the forebrain or prosencephalon. It is constituted by the structural derivatives of the telencephalon and diencephalon including the cerebral hemispheres, epithalamus, thalamus, hypothalamus, lateral ventricles and third ventricle. This definition is harmonious with the Federation of Association of Anatomist Second Edition (2019) Part V Terminologia Anatomica'.

Revision of concepts for abdomen and pelvis regions:

The relationships of the walls, cavities and contents of the abdomen and pelvis have undergone intensive review and re-work for more information please see https://docs.google.com/document/d/1gxkcEYf89eJl0RJG8-S2w4zOdpF8R2sn5SHx7InWxZI/edit?usp=sharing

The notion of ‘abdomen’ in clinical practice can vary between different specialties and circumstances; for example, ‘abdomen’ in natural language can be used to refer to, but not limited to, the following concepts:

• • Abdominopelvic cavity
  • Abdominopelvic cavity excluding the true pelvic cavity (Abdomen proper cavity)
  • Abdominopelvic cavity and/or content (Intra-abdominopelvic structure)
  • Intra-abdominopelvic structure excluding intra-pelvic structure of true pelvis
  • Intra-abdominopelvic structure and/or anterior abdominal wall
  • Intra-abdominopelvic structure and/or anterior abdominal wall, excluding intra-pelvic structure of true pelvis (Abdomen proper)
  • Abdominal segment of trunk
  • Abdominal cross-sectional segment of trunk

SNOMED International considers the most commonly used clinical variant referred to as ‘abdomen’ to be 818983003 |Structure of abdominopelvic cavity and/or content of abdominopelvic cavity and/or anterior abdominal wall (body structure)|, which in SNOMED CT is now the only concept using ‘Abdomen’ as a synonym. New concepts have been added to satisfy the requirements of imaging including:

• • Structure of abdominal cross-sectional segment of trunk (body structure)
  • Structure of pelvic cross-sectional segment of trunk (body structure)
  • Structure of abdominopelvic cross-sectional segment of trunk (body structure)
  • Structure of thoracic cross-sectional segment of trunk (body structure)

The different anatomical entities in this area have all been allocated a definition in order to bring clarity to this domain. A considerable number of definitions of disorders and procedures have been reviewed and rationalized according to these clearer principles. Further work on modeling updates for disorders and procedures, such as CT and MRI related to the abdomen has been planned for the next release. 

Review of Respiratory System

The hierarchical relationships for subtypes of 20139000 Structure of respiratory system (body structure) have been reviewed and improved, specifically:

• • 55214000 Bronchiole structure (body structure) was removed as a child of 955009 Bronchial structure (body structure) as this was causing inappropriate classification of many concepts, the parents are now 72674008 Bronchopulmonary segment structure (body structure) and 119198002 Tracheobronchial tree part (body structure).
  • Several ‘pharyngeal space concepts’ were deemed to be ambiguous and also there was some redundancy. These were modeled as pharyngeal structures however in reality they are not internal pharyngeal structures, although they are sometimes loosely described as such. Concepts using this terminology have been inactivated and relevant concepts are now organized under a new concept 789210002 Structure of peripharyngeal space (body structure).

2.2.1.2. New areas of content for Anatomy

New concepts added for Hair follicle of specific body regions.
New concepts added for spinal nerve proper at different levels.

2.2.1.3. Reference set updates

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

2.2.2. Clinical finding

New concepts added for clinical finding hierarchy: 1446

2.2.2.1. New content additions include

• Wound = 40 concepts
• Abrasion = 8 concepts
• Abscess = 13 concepts
• Benign neoplasm = 38 concepts
• Burn = 44 concepts
• Chemical burn = 36 concepts
• Closed fracture = 15 concepts
• Edema = 14 concepts
• Epidermal burn = 20 concepts
• Female genital mutilation type = 7 concepts
• Fracture = 10 concepts
• Full thickness burn = 14 concepts
• Hematoma = 13 concepts
• Infected wound = 23 concepts
• Injury = 33 concepts
• Laceration = 21 concepts
• Open fracture = 35 concepts
• Open wound = 108 concepts
• Partial thickness burn = 33
• Repetitive motion disorder = 19 concepts
• Subungual hematoma = 16 concepts
• Superficial foreign body = 14 concepts
  

2.2.2.2. Quality Initiative

The Quality Initiative (QI) project is the implementation of the Quality Strategy. After a successful pilot project for the July 2018 release the next stage has been implemented for subsequent releases including January 2020. 

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.

Total count of changes for the QI project: 

• Stated: A total of 9608 concepts had changes made to the Stated relationships in the model. 
• Inferred: A total of 16726 concepts affected by inferred changes.

2.2.2.3. Quality Improvement in the Clinical Finding Hierarchy

Inactivation of 33359002 |Degeneration (morphologic abnormality)|

In order to distinguish the degenerative process from the structure, 33359002 |Degeneration (morphologic abnormality)| has been inactivated as a DUPLICATE, SAME AS 107669003 |Degenerative abnormality (morphologic abnormality)|. All morphologies in the disorder hierarchy have been replaced accordingly. 

Inactivation of 23583003 |Inflammation (morphologic abnormality)

In order to distinguish inflammatory process from structure, 23583003 |Inflammation (morphologic abnormality)| has been Inactivated as DUPLICATE, SAME AS 409774005 |Inflammatory morphology (morphologic abnormality)|. All concepts in the Inflammatory disorder hierarchy have been remodeled accordingly. 

Revision of 129156001|Traumatic dislocation of joint (disorder)|

Traumatic dislocation concepts are being remodeled according to the new representation using DUE TO "Traumatic event". This work has been partially completed for the Jan 2020 release, resulting in the remaining subhierarchies moving from under "Traumatic dislocation of joint" to "Dislocation of joint". These remaining subhierarchies will be remodeled for the July 2020 release.

Revision of 298180004 |Finding of range of joint movement (finding)

The concepts under the subhierarchy 298180004 |Finding of range of joint movement (finding)|have been remodeled to represent the finding site of <<785818007 |Structure of joint region (body structure)| instead of <<39352004 |Joint structure (body structure)|.  Range of movement of a joint region can be impacted by both bone and soft tissues, therefore the use of 39352004 |Joint structure (body structure)| was too restrictive and caused issues in other areas of the terminology.  

Revision of Fracture Concepts 

Added new morphologic abnormality concepts in the following areas:

• • Neer classification of fracture of proximal humerus part fracture types (8 new concepts).
  • Seinsheimer classification of subtrochanteric femur fracture types I through V (5 new concepts).

This work led to changing relationships and definition status to "fully defined" for 6 fracture disorder concepts. Four qualifier value "Neer" fracture concepts were inactivated and referred to the new morphologic abnormality concepts.

2.2.2.4. Content Tracker Project Updates

Work continues on the following Content Project:

• IHTSDO- 393 Diabetes Complications: Diabetic complications have now been updated and modeled according to the updated Editorial Guidance and use of "DUE TO".
  Diabetic complications can be found in the hierarchy 74627003 |Complication due to diabetes mellitus (disorder)| which is a subtype of 116223007 |Complication (disorder)|. These concepts no longer reside as a subtype of 73211009 |Diabetes mellitus (disorder)|.
  The ECL query which will give a list of all diabetic complications modeled with a "DUE TO" is as follows:

  *: 42752001 |Due to (attribute)| = <<73211009 |Diabetes mellitus (disorder)|

  Work will begin with domain experts during the release cycle for July 2020 to update the clinical content in this area. 

2.2.2.5. Other Areas of Quality Improvement in the Clinical Finding Hierarchy

Remodel concepts - 254666005 |Keratosis (disorder)| 782957005 |Ichthyosis (disorder)| 396228006 |Hyperkeratosis (disorder)|

These concepts were all defined with "hyperkeratosis" and "skin". There was duplication across the concepts with synonyms and modeling. After consultation with clinical experts the following was agreed in summary:

Hyperkeratosis and Keratosis are the same.

Ichthyosis has an underlying morphology of "keratosis" but with a different distribution pattern.

Changes for 'On Examination' and 'Complaining of' concepts

The 'on examination' and 'complaining of' content is being returned to the UK as part of planned work for the July 2020 release. Where no suitable replacement concept exists new content without the 'examination' or 'complaining of' component of the meaning is being created.

For example:  Eye does not move left (finding) has been added in preparation for the inactivation of 'On examination - eye does not move left (finding)'.

For the January 2020 release 180 new concepts were added.

Inactivation - "Finding of form of X (finding)"

Inactivation of 30 concepts using the format "Finding of form of ..."

Remodel 70153002 |Hemorrhoids (disorder)|

Improvements made in the modeling of subtypes of 70153002 |Hemorrhoids (disorder)|.

Changes to Case Sensitivity

Over 31,000 descriptions have been reviewed and approximately 5,402 descriptions across 2806 concepts have had their case significance settings corrected as appropriate.  The changes are across all SNOMED CT hierarchies but in particular disorder concepts (1774), procedure (978) and qualifier values (736). The Editorial Guidance on case significance related to descriptions containing numeric values and special characters has been updated for the January 2020 release.

2.2.3. Convergent Medical Terminologies (CMT)

New CMT concepts: 775

The majority of these newly authored concepts are in scope for mapping to ICD-10 and from the following domains:

• CMT Injuries - 106
• CMT Mixed Domains - 584
• CMT Musculoskeletal - 22
• CMT Ophthalmology - 20
• CMT Orthopedics - 43

2.2.4. Procedure

New concepts for procedure hierarchy: 105

2.2.4.1. Areas of Quality Improvement for the Procedure Hierarchy

Implantation and Insertion procedures

Work commenced on content tracker IHTSDO-175. There are ongoing structural changes for the Procedure concepts related to the content tracker: It was agreed that not all Insertion and Implantation procedures are surgical. As a result, further work in the hierarchy under 129284003 |Surgical action (qualifier value)| has been undertaken for the January 2020 release and this includes:

• • Reactivation of 129338005 |Surgical implantation - action (qualifier value)|
  • Addition of a new concept 788288006 |Surgical reimplantation - action (qualifier value)|
  • Remodel of 'Reimplantation procedures' replaced METHOD = 129337000 |Reimplantation - action (qualifier value)| with new 788288006 |Surgical reimplantation - action (qualifier value)|

Work on this project will continue for future releases after January 2020.

Evaluation Procedures

• • Inactivated four duplicate concepts.
  • Inactivated six ambiguous concepts.
  • Inactivated one erroneous concept.
  • Created one new concept to replace an ambiguous concept.
  • Inactivated descriptions of sixteen concepts.
  • Removed incorrect parent for two concepts.
  • Added descriptions to fourteen concepts.

Changes to Existing Concepts in the Procedure Hierarchy

The following concepts and/or areas in the procedure hierarchy were remodeled:

• • Osteopathic manipulation techniques
  • Emergency coronary artery bypass graft
  • Tylectomy
  • Neck excision
  • Procedure on brain ventricular shunt
  • Change of diaper
  • Removal of leeches
  • Dermabrasion of facial scars
  • Triennial health exam
  • Detoxification therapy (regime/therapy)
  • Hormone therapy replacement
  • Transplantation of dura
  • Cervical biopsy
  • Excisional biopsy of cerebral meninges, percutaneous, needle
  • Suture of plexus
  • Oral fluorescence imaging
  • Administration of heavy metal antagonist

2.2.5. Collaboration/Harmonization Projects

2.2.5.1. Orphanet

Working in collaboration with Orphanet (http://www.orpha.net/consor/cgi-bin/index.php), creation of new concepts for the original set of prioritized rare diseases has been completed. 

The mapping and validation process has begun for an alpha release after the January 2020 International release of SNOMED CT. 

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

2.2.5.2. Global Medical Device Nomenclature Agency (GMDNA)

21 new device concepts were added to the physical object hierarchy for GMDN.

4 device concepts were inactivated.

For the GMDN mapping equivalence tables: 

• • 21 New concepts have been added to inscope and mapped.
  • 161 concepts have been modified and removed from the mapping tool as out of scope.
  • 92 concepts ave been deemed obsolete and removed from the mapping tool and flagged as out of scope.
  • 334 concepts were identified as no longer in scope for the map and have been removed. These concepts were identified as part of the Quality Improvement of the mapping equivalence tables and the monthly submissions from GMDN.

2.2.5.3. ICD-O-3.2 Update

For the January 2020 release, and based on the recent release of ICD-O-3.2 the priority has being adding new content for updated morphologies; this refers to additions to the 400177003 |Neoplasm and/or hamartoma (morphologic abnormality)| sub-hierarchy. Approximately 63 changes in the sub-hierarchy are related to the ICD-O-3.2 update analysis, including the direct addition of 25 new morphology concepts that were identified from analysis of the ICD-O-3.2 preview as missing from SNOMED CT.

Impacted concepts in the disorder hierarchy have been revised to align with any new ICD-O-3.2 morphology changes, and in many cases the addition of a relationship to the new morphology concept has resulted in the neoplasm disorder concept being defined fully. This work has included the creation of a small number of new neoplasm disorder concepts to match the new morphologies.

Descriptions with [obs] have been inactivated as outdated because they are artefacts of descriptions from the ICD-O-3 print version for their history tracking. There are two concepts and one synonym with [obs] that remain and will be addressed for the July 2020 release.

2.2.6. Event

New concepts added: 16

2.2.7. Qualifier Value

New concepts added: 88

2.2.8. Situation with explicit context 

New concepts added: 31

This includes 17 new concepts for 'History of X'.

2.2.9. Observable Entity 

New concepts added: 136

This includes 8 new concepts for insulin dose observables.

2.2.10. Organism

New organism concepts added: 185

• • Added new descriptions for 10 organism concepts.
  • Inactivated 9 organism concepts as duplicates.
  • Changed descriptions of two organism concepts.
    

2.2.11. Pharmaceutical / biologic product

2.2.11.1. Changes for Pharmaceutical / biologic product 

Inactivation of 'Over the Counter'

Concepts referring to “over the counter” status have been inactivated.

Concepts referring to regulatory status or characterization (e.g. over the counter) are out of scope for the International Release since the meaning may vary by jurisdiction and is not consistent internationally.

Vaccine Poisoning

Concepts referring to vaccine poisoning have been inactivated from the January 2020 International release and moved to the NHS extension per their request.

The notion of vaccine poisoning has persisted in ICD 10 under T50 but it is not included in ICD-11; the poisoning aspect seemingly referred to the adjuvants and carriers that are included in the vaccines as opposed to the biological component itself.

2.2.12. Veterinary Extension

7 concepts were moved to the Veterinary Extension. 

2.2.13. Social Context

New concepts added: 1

2.2.14. Specimen

New concepts added: 3

2.4.1.1. 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. 

2.4.1.2.  Mapped content for January 2020

The map provided for the January 2020  release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2016 version.

• 1501 new concepts added
  
• Quality improvement continues and Map QA project 51 resulted in revision of 27 concepts to represent sclerosis of bypass grafts.
• Map QA project 55, Fractures without external cause advice, was completed resulting in revision of 70 concepts.
• Map QA project 60, 328 concepts have been reviewed for inconsistent map advice. The focus was the SNOMED to ICD-10 Chapter X1V Diseases of the genitourinary system (N00-N99).
  
  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

2.4.1.3. 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:  http://snomed.org/icd10map

2.4.2. ICD-O Map

The maps to ICD-O-3.1 are being updated only for error correction purposes for the January 2020 release. The maps to ICD-O-3.2 are out of scope for the January 2020 release and are planned for a future release when the ICD-O-3.2 classification has been published by WHO (IARC).

As part of the initial QA process 34 ICD-O-3.1 morphology maps to grouper concepts with "- category" in the FSN were removed and assigned a 'no target' map in preparation for the ICD-O-3.2 update.

For the January 2020 release a total of 69 morphology concepts in the 400177003 Neoplasm and/or hamartoma (morphologic abnormality) sub-hierarchy were mapped. 31 were mapped to ICD-O-3.1 morphology codes and 38 assigned a 'no target' map (consisting mainly of new morphology concepts) awaiting the ICD-O-3.2 update and availability of new codes in the mapping tool. For example new concept 788565009: Indolent T-cell lymphoproliferative disorder of gastrointestinal tract (morphologic abnormality) has no target map until ICD-O-3.2 is available but the new morphology has been used to fully define the disorder concept 783565007 Indolent T-cell lymphoproliferative disorder of gastrointestinal tract (disorder).

SNOMED CT to OWL conversion and classificationThe 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 capacity within the current editing cycle, 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 SNOMED CT January 2020 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 the Alpha and Beta testing of the current release, which were resolved before the final deployment of the associated Member 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 Snomed CT January 2020 International edition can be found here:

3.2.1. Technical updates

3.2.1.1. 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.

3.2.1.2. Early visibility of impending change in the January 2020 International edition

Please see the following page for details of all upcoming changes planned for January 2020 and beyond:  January 2020 Early Visibility Release Notices - Planned changes to upcoming SNOMED International Release packages.

3.2.1.3. Release Notes naming convention

The Release notes naming convention has been refined to bring it in line with other documentation standards - from this release onwards the files will have the following naming format:

• • doc_SnomedCTReleaseNotes_Current-en-US_INT_[date].pdf

   Instead of the previous underscore after "Current":

• • doc_SnomedCTReleaseNotes_Current_en-US_INT_[date].pdf

3.2.1.4. Document links

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.