Excludes1 pair
G35.A vs G37.9
G35.A and G37.9 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 G35.A
demyelinating disease of central nervous system, unspecified (G37.9)
G35.A
Relapsing-remitting multiple sclerosis
Billable
- Chapter 6
- Diseases of the nervous system
- Section
- G35-G37
Indexed under
- Sclerosis, sclerotic › multiple › relapsing-remitting
G37.9
Demyelinating disease of central nervous system, unspecified
BillableUnspecified
- Chapter 6
- Diseases of the nervous system
- Section
- G35-G37
Use when the record says
- Clinically isolated syndromes
Indexed under
- Degeneration, degenerative › myelin, central nervous system
- Demyelination, demyelinization › central nervous system
- Disease, diseased › demyelinating, demyelinizating (nervous system)
- Sclerosis, sclerotic › brain (generalized) (lobular)
- Syndrome › clinically isolated
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