A87.9 vs A88
A87.9 and A88 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 A88
viral meningitis NOS (A87.9)
A87.9
Viral meningitis, unspecified
BillableUnspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A80-A89
Indexed under
- Meningitis › viral NEC (basal) (basic) (brain) (cerebral) (cervical) (congestive) (diffuse) (hemorrhagic) (infantile) (membranous) (metastatic) (nonspecific) (pontine) (progressive) (simple) (spinal) (subacute) (sympathetic) (toxic)
A88
Other viral infections of central nervous system, not elsewhere classified
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A80-A89
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