Excludes1 pair

I38 vs Q24.8

I38 and Q24.8 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 I38
congenital insufficiency of cardiac valve NOS (Q24.8)
I38

Endocarditis, valve unspecified

BillableUnspecified
Chapter 9
Diseases of the circulatory system
Section
I30-I5A
Use when the record says
  • endocarditis (chronic) NOS
  • valvular incompetence NOS
  • valvular insufficiency NOS
  • valvular regurgitation NOS
  • valvular stenosis NOS
  • valvulitis (chronic) NOS
Indexed under
  • Endocarditis (chronic) (marantic) (nonbacterial) (thrombotic) (valvular)
  • Disease, diseased › valve, valvular
  • Endocarditis › arteriosclerotic
  • Insufficiency, insufficient › valve, valvular (heart)
  • Stenosis, stenotic › heart valve
Q24.8

Other specified congenital malformations of heart

BillableUnspecified
Chapter 17
Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
Section
Q20-Q28
Use when the record says
  • Congenital diverticulum of left ventricle
  • Congenital malformation of myocardium
  • Congenital malformation of pericardium
  • Malposition of heart
  • Uhl's disease
Indexed under
  • Cordis ectopia
  • Ectocardia
  • Hemicardia
  • Uhl's anomaly or disease
  • Absence › pericardium (congenital)

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