coding-icd10

Coding OpenMed diagnoses to ICD-10-CM / PCS

Suggest ICD-10-CM diagnosis codes (and ICD-10-PCS for inpatient procedures) for the diagnosis and procedure spans OpenMed extracts. This is decision support for a certified coder, not autonomous billing: OpenMed + this skill narrow the candidate set and explain why; a human validates the final, billable code.

ICD-10-CM and ICD-10-PCS are public domain. CMS publishes the complete annual code files, addenda, and indexes for free. (CPT/HCPCS procedure codes are AMA-licensed and restricted — out of scope here; obtain those separately under the user's own AMA license.)

When to use

• A note yields diagnoses ("type 2 diabetes with diabetic CKD", "community- acquired pneumonia") and you want candidate ICD-10-CM codes plus rationale.
• You need to route a span to the right chapter quickly (see references/icd10-chapters.md for code ranges).
• You hold legacy ICD-9 codes and need an approximate GEM cross-walk.
• You are pre-filling encounter diagnoses for a coder's review queue.

For clinical-meaning codes use mapping-to-snomed; for HCC/risk capture use coding-hcc-risk-adjustment; this skill is for the ICD-10 classification.

Quick start (public data + public FHIR lookup)

Two complementary paths, both license-clean:

A) CMS files, loaded locally (public domain; you download once):

# CMS publishes the order/addenda file; load the code->description table.
# Columns: code (no dot), description; you insert the dot for display.
icd10cm = {}                       # "E1122" -> "Type 2 diabetes mellitus with diabetic chronic kidney disease"
with open("icd10cm_order_2025.txt", encoding="latin-1") as fh:
    for line in fh:
        code = line[6:13].strip()
        billable = line[14] == "1"     # '1' = valid billable code
        long_desc = line[77:].strip()
        if billable:
            icd10cm[code] = long_desc

def search_local(term: str, limit: int = 5):
    t = term.lower()
    hits = [(c, d) for c, d in icd10cm.items() if t in d.lower()]
    return sorted(hits, key=lambda cd: len(cd[1]))[:limit]