2026-02-18 - Laboratory Terminology Standards WG Meeting
18th February 2026
GoToMeeting Details
Zoom link - https://snomed.zoom.us/my/pathologycrg
Attendees @Young Bae @GunnarEza HafezaRob Hausam @Pam Banning Farzaneh Ashrafi@ Scott Campbell @Gogs Karim Nashar
Apologies
Recording (Cloud)
Passcode: 5MYuU=GP
Discussion items
Item | Description | Owner | Notes | Action |
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1 | Microbiology structured reporting design |
| Last meeting summary Recap The meeting focused on discussions about organism identification methods and coding approaches for microbiology laboratory results, including possible requirements for using separate codes for ordinal versus quantitative measurements in susceptibility testing. The team explored challenges around terminology patterns, machine readability, and the integration of toxigenic strain identification into laboratory information systems. Post-coordinated Nucleic Acid Identification Karim discussed the representation of organism isolates and identification methods with the HL7 Europe group. They agreed to use a post-coordinated approach for nucleic acid identification, where the organism name is included in the test name and ordinal presence concepts are used. Karim also mentioned that they need to further investigate the suitability of existing content for susceptibility testing, as there may be quantitative versions that require different handling. Susceptibility Testing Coding Discussion The team discussed the coding of susceptibility testing results, particularly focusing on whether to use separate codes for ordinal (resistant/susceptible) and quantitative (MIC value) measurements. Karim raised concerns about machine readability and interoperability, suggesting that having separate codes could be more precise, while Pam and Rob noted that the current single-code approach has worked for 30 years. Karim expressed interest in reviewing the relevant codes (particularly the NPU requirements) and mentioned waiting for Stan's analysis. Toxigenic Strain Identification in Labs Rob and Karim discussed the importance of identifying toxigenic strains of Clostridium difficile and other organisms in laboratory reports. They explored how pre-coordinating organism codes with toxigenic properties can enhance clinical significance. Pam inquired about how these processes are implemented in laboratory information systems (LIS), suggesting that algorithms might not be necessary for predicting report outputs. Rob acknowledged the complexity of integrating these processes into LIS and noted the need for a mechanism to report out such information effectively. Microbiology Terminology and Interoperability Updates The group discussed terminology patterns for microbiology and semantic interoperability challenges. They agreed to include updates from LOINC and NPU, as well as a presentation from the genomics unit at NHS England, in the April business meeting agenda. The group also touched on the need to address semi-quantitative reporting in laboratory results, which remains a challenge to be explored further.
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Actions log
Item | Description | Owner | Notes | Action |
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1 | SARS-Cov2 observable entity concepts for reporting viral RNA presence in the SNOMED CT International Edition | FA | These concepts are modelled with both inheres_in and direct_site | Farzaneh to take these back and discuss internally for a steer on the use of inheres_in for these concepts On hold SI propose to remove inheres_in but await formal decision from this group |
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Issues and decisions log
Item | Description | Owner | Notes | Decision |
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1 | Time aspect specification in description AND modelling | All | Concept is primitive if the description is more specific than the modelling. Concept logical definition must not be more specific than concept description LOINC uses time_aspect NPU is implied Definition - Time of specimen collection | Must be stated consistently in description AND modelling in accordance with SI editorial policy modelling single point in time explicitly to enable correct classification of content Time-specific concepts must not be subsumed by unmodelled soft default implicit 'single point in time' concepts UK NRC to discuss applying the same principle |
2 | Inheres_in for sample based diagnostic reporting | All | Inheres_in effectively duplicates direct_site. They are two different perspectives (lab and clinical) of the same target Direct_site is suitable for sample-based diagnostics and not other areas but NPU will not be following those guidlines In Cancer Synoptic histology - carcinoma inheres_in neoplasm, when specimen is taken, the direct_site is specimen LOINC and NPU share linkage via 3 attributes, as SNOMED CT concepts they will classify as siblings, because of the different use of Inheres_in and direct_site Can compute mapping using ECL Some challenges e.g. NPU uses units, LOINC does not ---------------- e.g. mass content of mercury in hair mass content of iron in liver Body structure is used for inheres_in for NPU-SNOMED CT project This enables modelling location of hair from body structure hierarchy also model cell structures - e.g. in erythrocytes use a specimen value of inheres in if the observable was specifically about the specimen (e.g. specimen volume). ALL - Hair length can be another observation in FHIR observation group i.e. one observation to represent mass content of mercury in hair; and another observation to represent length of hair with a codable concept e.g. 12704-3 Length of hair The mercury content inheres in the hair follicles were the hair structure was created and at the time when the structure was created. the hair acts as a physical memory and integrator of mercury exposure https://www.annclinlabsci.org/content/36/3/248.full
| Direct_site attribute sufficiently captures specimen and derivable substance / site from specimen modelling LOINC Ontology to model direct_site NPU to model inheres_in Create interoperable rules and document in guidance LOINC and NPU take different approached (to be documented) UK NRC need to decide and test approach with LOINC Ontology content for UK gap requirements |
3 | Representation of percent | All | Concept is primitive if the description is more specific than the modelling. Concept logical definition must not be more specific than concept description
unit not required field in LOINC so in SNOMED CT, if fully defined without unit, could generate logical equivalences | Represent percent in the description and the unit in SNOMED CT in accordance with SI editorial policy LOINC Committee decided to remove 100 denominator and reflect percent as UoM. LOINC Ontology will only release codes with 'fraction property (e.g number fraction, mass fraction)' and percent will be identified by unit. Percent unit is used with NPU. NPU is more standardised with use of units so there is less variation (e.g. for substance conc, one unit) International content will continue to model percent unit according to cancer synoptic content - any question mark for moving to LOINC Ontology? UK will maintain SNOMED CT percentage subtypes to support the UK labs migration from Read, modelling percent unit as standardised exceptions, but align to LOINC Ontology properties in order to compute equivalences (when combined with unit %) and classify as subtypes if needed
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4 | Inconsistencies - International content for cancer synoptic reporting by immunohistochemistry 1255078008 | Percent of cell nuclei positive for proliferation marker protein Ki-67 in primary malignant neoplasm by immunohistochemistry (observable entity) | | All | Does not use percent unit in modelling e.g. 1 - modelling time_aspect -> single point in time but not stating this in the description In contrast to LOINC Ontology examples that do state 'at single point in time' in the description and model in the logic e.g.2 - use inheres_in whereas LOINC Ontology used direct_site | SI are adding percent unit to the content Awaiting formal decision on inheres_in from this group Awaiting formal decision on time_aspect from this group |
5 | Qualitative and semi-quantitative representation in SNOMED CT | KN | How do we represent both axes of ordinal AND qualitative / semi-q in SNOMED CT model? NPU descriptions in this link (not complete yet): https://labterminology.com/npu-concept-model/general-rules-on-result-type/... Hierarchies are inconsistent for qualifiers that represent the targets of scale_type defining attribute for observable entity concepts (see presentation slides)
| Both are ordinal scales Both represented as presence in LOINC and international SNOMED CT Semi-q needs to be defined UK need to make a distinction between qualitative and semi-q in the terminology |
6 | Relative concentration of a substance in two different specimens Relative concentration two different measurement properties CALCULATIONS | KN / DK | How do we assess effort vs impact? The requirement to model them accurately for machine reasoning - auto-classifications; erroneous subsumptions Karim reviewed the modelling options with Daniel and presented to group | Young Bae recommended we look at IUPAC relative properties and ratios Patient test results calculations - consistent approach to reference external formulae, and not represent in SNOMED CT observable entity concept model (including ratios)
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7 | Fractions and ratios |
| After review of the resources, internal discussions and a review with the LOINC team, we've determined that "Ratio" and "Fraction" should be classified as sibling properties. IFCC-IUPAC Silverbook https://iupac.org/what-we-do/books/silverbook/ but also on the homepage: https://labterminology.com/list-of-kinds-of-property/ NOTES Mass content is deprecated in the IUPAC green book Mass content and mass fraction are equivalent No change required to SNOMED CT properties NPU can map mass fraction to LOINC / SNOMED CT mass content Mass fraction - of components (e.g. haemoglobin types) Mass content - of the specimen (e.g. hair sample, calculus)
NPU is in agreement with LOINC for mass ratios and relative concentrations (mass or molar) Expand ratios and relative concentrations in the terminology descriptions e.g. Ratio of mass concentration of protein to substance concentration of creatinine in urine at point in time Ratio of mass concentration of creatinine to mass concentration of protein in urine at point in time | Agreement to have sibling properties and not subtypes for fraction and ratio Agreement on suggested terminology for FSN of ratios of different measurement properties and creation of new properties for mass/mol and mol/mass |
8 | Use of inheres_in for colour, appearance, identification | FA | inheres_in used for the property to describe the characteristic of an organism, cell or body structure - applicable to LOINC Ontology representations | See Farazaneh's slides - 2025-04-08 - SI April Business Meeting Laboratory Terminology Standards WG - Room: Munch 2 - Laboratory reporting working group - SNOMED Confluence |
9 | Microbiol0gy decisions |
| Placeholder - will summarise outputs once HL7 white paper is drafted |
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