I00 vs M02
I00 and M02 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on M02
rheumatic fever (I00)
I00
Rheumatic fever without heart involvement
Billable
- Chapter 9
- Diseases of the circulatory system
- Section
- I00-I02
Use when the record says
- arthritis, rheumatic, acute or subacute
Indexed under
- Fever › rheumatic (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- Pneumonia › rheumatic (acute) (double) (migratory) (purulent) (septic) (unresolved)
- Rheumatic › pneumonia (acute) (subacute)
- Erythema, erythematous › marginatum › inacute rheumatic fever (infectional) (inflammation)
- Pneumonia › in › rheumatic fever (acute) (double) (migratory) (purulent) (septic) (unresolved)
M02
Postinfective and reactive arthropathies
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M00-M02
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027