Excludes1 pair
B51- vs B53.1
B51 and B53.1 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 B53.1
Malaria due to simian plasmodia with Plasmodium vivax (B51.-)
B51
Plasmodium vivax malaria
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B50-B64
Use when the record says
- mixed infections of Plasmodium vivax with other Plasmodium species, except Plasmodium falciparum
B53.1
Malaria due to simian plasmodia
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- B50-B64
Indexed under
- Monkey malaria
- Simian malaria
- Malaria, malarial › Plasmodium › simian
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