Hi LOINC team,
I’m preparing a coordinated LOINC submission for structured results from our carrier screening, cfDNA NIPT, and fetal antigen testing, and would appreciate brief pre-submission guidance on a few modeling questions before we submit the batch formally.
We reviewed 98 result codes and sorted them into three groups:
- 31 appear to map cleanly to existing LOINC codes, included for context only; no new requests planned for these.
- 9 have candidate existing codes, but we’re not confident the existing terms fully represent our reported result values.
- 58 appear to require new or revised terms, primarily for fetal antigen NIPT, single-gene NIPT, and carrier-result interpretations.
We’d especially value your guidance on three issues:
1. Modeling novel cfDNA fetal-antigen results
Our fetal antigen results are predicted from maternal plasma cell-free DNA. We’re currently modeling them after LOINC 100670-9: a gene-allele Component with a Plas.cfDNA^Fetus construction, reported as presence/threshold with ordinal values such as Detected / Not Detected, rather than as a serologic fetal red-cell antigen construction.
Does that approach seem appropriate for the broader fetal antigen panel, including RHCE, KEL, Duffy, Kidd, MNS, and HPA platelet antigens? Or would LOINC prefer these modeled as fetal red-cell or platelet antigen phenotype terms instead?
2. Carrier-screen result interpretations
Most of our carrier results are reported to providers as a collapsed NEGATIVE / POSITIVE interpretation. The closest existing terms we found are gene mutation-analysis terms with identity, document, or method-specific constructions. For example, some interpretive carrier terms include a specific method such as MS.MALDI-TOF — e.g., 77017-2 — whereas our result is a method-agnostic molecular carrier interpretation.
For NEGATIVE / POSITIVE carrier interpretations by molecular genetics, would LOINC prefer that we reuse existing interpretive terms where available, request changes to existing terms, or submit new method-agnostic interpretive terms? This affects approximately 13 of our result codes.
3. Candidate terms with incomplete answer-value coverage
For several results, a candidate code is close but may not cover all reported values. For example, our 22q11.2 result reports Low Risk / High Risk and maternal findings such as maternal_duplication and maternal_deletion. The existing fetal 22q11.2 deletion risk term, 88572-3, appears to cover the fetal risk interpretation but not necessarily the maternal findings.
For cases like this, would you advise using the existing code with local answer values, requesting a new distinct observation, or submitting a change request / revised term?
Happy to share our full crosswalk, including all three buckets with candidate codes, proposed names, and rationale, on request.
Thank you for any guidance before we submit. We’re aiming to keep the formal submission as clean and easy to review as possible.