Excludes1 pair
A39.9 vs A49-
A39.9 and A49 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 A49
meningococcal infection NOS (A39.9)
A39.9
Meningococcal infection, unspecified
BillableUnspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A30-A49
Use when the record says
- Meningococcal disease NOS
Indexed under
- Meningococcus, meningococcal
- Infection, infected, infective › meningococcal
- Infection, infected, infective › parameningococcus NOS
A49
Bacterial infection of unspecified site
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A30-A49
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