Excludes1 pair
A92- vs B33.1
A92 and B33.1 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 A92
Ross River disease (B33.1)
A92
Other mosquito-borne viral fevers
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A90-A99
B33.1
Ross River disease
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B25-B34
Use when the record says
- Epidemic polyarthritis and exanthema
- Ross River fever
Indexed under
- Ross River disease or fever
- Disease, diseased › Ross River
- Fever › Ross River
- Polyarthritis, polyarthropathy › epidemic (Australian) (with exanthema)
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