Excludes1 pair

B57.0 vs I41

B57.0 and I41 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 I41
acute (B57.0)
B57.0

Acute Chagas' disease with heart involvement

Billable
Chapter 1
Certain infectious and parasitic diseases
Section
B50-B64
Use when the record says
  • Acute Chagas' disease with myocarditis
Indexed under
  • Chagas' › acute › cardiovascular NEC
  • Chagas' › acute › myocarditis
  • Cardiomyopathy › in › Chagas' disease › acute
I41

Myocarditis in diseases classified elsewhere

Billable
Chapter 9
Diseases of the circulatory system
Section
I30-I5A
Indexed under
  • Myocarditis › in › epidemic louse-borne typhus
  • Myocarditis › in › typhus NEC

These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.

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