A85 vs B25.8
A85 and B25.8 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 A85
encephalitis due to cytomegalovirus (B25.8)
A85
Other viral encephalitis, not elsewhere classified
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A80-A89
Use when the record says
- specified viral encephalomyelitis NEC
- specified viral meningoencephalitis NEC
B25.8
Other cytomegaloviral diseases
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B25-B34
Use when the record says
- Cytomegaloviral encephalitis
Indexed under
- Disease, diseased › cytomegaloviral › specified NEC
- Encephalitis › in › cytomegalovirus (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)
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