A85 vs B05.0
A85 and B05.0 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 measles virus (B05.0)
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
B05.0
Measles complicated by encephalitis
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B00-B09
Use when the record says
- Postmeasles encephalitis
Indexed under
- Encephalitis › postmeasles (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)
- Encephalomyelitis › postmeasles
- Encephalitis › in › measles (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)
- Measles › with › encephalitis (black) (hemorrhagic) (suppressed)
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