Excludes1 pair
M30.0 vs M31.7
M30.0 and M31.7 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on M31.7
polyarteritis nodosa (M30.0)
M30.0
Polyarteritis nodosa
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M30-M36
Indexed under
- Panangiitis
- Panarteritis nodosa
- Periarteritis nodosa (disseminated) (infectious) (necrotizing)
- Polyangiitis
- Arteritis › nodosa
M31.7
Microscopic polyangiitis
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M30-M36
Use when the record says
- Microscopic polyarteritis
Indexed under
- Microscopic polyangiitis (polyarteritis)
- Polyangiitis › microscopic
- Polyarteritis › microscopic
- Disorder › glomerular › microscopic polyangiitis
- Glomerulonephritis › in › microscopic polyangiitis
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