ICD-10-CM 2027
ICD-10 code for Hydrancephaly
From the official ICD-10-CM alphabetic index entry “Hydrancephaly, hydranencephaly”. Page updated September 29, 2026.
About coding Hydrancephaly
The ICD-10-CM code for Hydrancephaly is Q04.3 (Other reduction deformities of brain).
Within Q04, choose Q04.3 (Other reduction deformities of brain) only when documentation doesn't support a more specific option: congenital malformations of corpus callosum (Q04.0), Arhinencephaly (Q04.1), holoprosencephaly (Q04.2), Septo-optic dysplasia of brain (Q04.4), Megalencephaly (Q04.5), congenital cerebral cysts (Q04.6), other specified congenital malformations of brain (Q04.8) and congenital malformation of brain, unspecified (Q04.9).
Don't report Q04.3 together with the conditions in its Excludes1 note: congenital malformations of corpus callosum (Q04.0).
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.
More specific Hydrancephaly codes (official index)
- with spina bifida
Don't confuse with (Excludes1 for Q04.3)
- congenital malformations of corpus callosum (Q04.0)
Common questions about Hydrancephaly ICD-10 codes
What is the ICD-10 code for Hydrancephaly?
- Q04.3 — Other reduction deformities of brain.
Is Q04.3 billable?
- Yes. Q04.3 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q04.3 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q04.3 as a principal diagnosis.
Is Q04.3 a CC or MCC?
- Q04.3 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.