Excludes1 pair

B50- vs B53.0

B50 and B53.0 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 B53.0
Plasmodium ovale with Plasmodium falciparum (B50.-)
B50

Plasmodium falciparum malaria

Not billable
Chapter 1
Certain infectious and parasitic diseases
Section
B50-B64
Use when the record says
  • mixed infections of Plasmodium falciparum with any other Plasmodium species
B53.0

Plasmodium ovale malaria

Billable
Chapter 1
Certain infectious and parasitic diseases
Section
B50-B64
Indexed under
  • Fever › Plasmodium ovale
  • Malaria, malarial › ovale
  • Malaria, malarial › Plasmodium › ovale

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