FY2027
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Excludes1 pair

Q04.8 vs Q07.0-

Q04.8 and Q07.0 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 Q07.0
Arnold-Chiari syndrome, type IV (Q04.8)
Q04.8

Other specified congenital malformations of brain

BillableUnspecified
Chapter 17
Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
Section
Q00-Q07
Use when the record says
  • Arnold-Chiari syndrome, type IV
  • Macrogyria
Indexed under
  • Macrogyria (congenital)
  • Ulegyria
  • Arnold-Chiari disease, obstruction or syndrome › type IV
  • Displacement, displaced › brain stem, caudal (congenital)
  • Displacement, displaced › cerebellum, caudal (congenital)
Q07.0

Arnold-Chiari syndrome

Not billable
Chapter 17
Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
Section
Q00-Q07
Use when the record says
  • Arnold-Chiari syndrome, type II

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