Excludes1 pair
M79.0 vs M79.7
M79.0 and M79.7 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 M79.0
fibromyalgia (M79.7)
M79.0
Rheumatism, unspecified
BillableUnspecified
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M70-M79
Indexed under
- Rheumatism (articular) (neuralgic) (nonarticular)
M79.7
Fibromyalgia
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M70-M79
Use when the record says
- Fibromyositis
- Fibrositis
- Myofibrositis
Indexed under
- Fibromyalgia
- Fibromyositis
- Fibrositis (periarticular)
- Myofibrositis
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