FY2027
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Excludes1 pair

I00 vs I01.0

I00 and I01.0 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 I00
rheumatic fever with heart involvement (I01.0 -I01.9)
I00

Rheumatic fever without heart involvement

Billable
Chapter 9
Diseases of the circulatory system
Section
I00-I02
Use when the record says
  • arthritis, rheumatic, acute or subacute
Indexed under
  • Fever › rheumatic (active) (acute) (chronic) (subacute)
  • Pneumonia › rheumatic
  • Rheumatic › pneumonia
  • Erythema, erythematous › marginatum › in acute rheumatic fever (due to)
  • Pneumonia › in › rheumatic fever
I01.0

Acute rheumatic pericarditis

Billable
Chapter 9
Diseases of the circulatory system
Section
I00-I02
Use when the record says
  • Any condition in I00 with pericarditis
  • Rheumatic pericarditis (acute)
Indexed under
  • Pericarditis › rheumatic (active) (acute) (with effusion) (with pneumonia)
  • Rheumatic › pericarditis (active) (acute) (with effusion) (with pneumonia)
  • Pericarditis › acute › rheumatic

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