Excludes1 pair
B33.3 vs B34-
B33.3 and B34 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 B34
retrovirus infection NOS (B33.3)
B33.3
Retrovirus infections, not elsewhere classified
BillableUnspecified
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B25-B34
Use when the record says
- Retrovirus infection NOS
Indexed under
- Infection, infected, infective › retrovirus
- Human › T-cell lymphotropic virus › type-1 infection (HTLV-I)
- Infection, infected, infective › human › T-cell lymphotropic virus type-1 (HTLV-1)
B34
Viral infection of unspecified site
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B25-B34
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