Excludes1 pair
Q23.4 vs Q25.4-
Q23.4 and Q25.4 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 Q25.4
hypoplasia of aorta in hypoplastic left heart syndrome (Q23.4)
Q23.4
Hypoplastic left heart syndrome
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q20-Q28
Indexed under
- Hypoplasia, hypoplastic › left heart syndrome
- Syndrome › hypoplastic left-heart
- Atresia, atretic › aortic › congenital with hypoplasia of ascending aorta and defective development of left ventricle (with mitral stenosis)
- Atresia, atretic › aortic › in hypoplastic left heart syndrome
- Atresia, atretic › mitral valve › in hypoplastic left heart syndrome
Q25.4
Other congenital malformations of aorta
Not billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q20-Q28
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