Q04.0 vs Q04.3
Q04.0 and Q04.3 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on Q04.3
congenital malformations of corpus callosum (Q04.0)
Q04.0
Congenital malformations of corpus callosum
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q00-Q07
Use when the record says
- Agenesis of corpus callosum
Indexed under
- Absence › corpus callosum (of) (organ or part) (complete or partial)
- Agenesis › corpus callosum
- Aplasia › corpus callosum
- Hypoplasia, hypoplastic › corpus callosum
- Malformation › corpus callosum (congenital)
Q04.3
Other reduction deformities of brain
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q00-Q07
Use when the record says
- Absence of part of brain
- Agenesis of part of brain
- Agyria
- Aplasia of part of brain
- Hydranencephaly
- Hypoplasia of part of brain
- Lissencephaly
- Microgyria
Indexed under
- Agyria
- Hydrancephaly, hydranencephaly
- Lissencephalia, lissencephaly
- Microgyria (congenital)
- Pachygyria
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