Excludes1 pair
A87- vs B26.1
A87 and B26.1 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 A87
meningitis due to mumps virus (B26.1)
B26.1
Mumps meningitis
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B25-B34
Indexed under
- Mumps › meningitis (aseptic)
- Meningitis › in › mumps (virus)
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