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G91

⚠ Non-billable (Header)

Hydrocephalus

Diseases of the nervous system (G00-G99)

⚠️ This is a category header code — not billable. Use a more specific child code below.

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✅ Includes

  • • acquired hydrocephalus

❌ Excludes1

direct

Cannot be coded with G91

  • • Arnold-Chiari syndrome with hydrocephalus (Q07.-)
  • • congenital hydrocephalus (Q03.-)
  • • spina bifida with hydrocephalus (Q05.-)

Child Codes (7)

G91.0Communicating hydrocephalusG91.1Obstructive hydrocephalusG91.2(Idiopathic) normal pressure hydrocephalusG91.3Post-traumatic hydrocephalus, unspecifiedG91.4Hydrocephalus in diseases classified elsewhereG91.8Other hydrocephalusG91.9Hydrocephalus, unspecified

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Code Information

CodeG91
BillableNo — Header code
CategoryDiseases of the nervous system (G00-G99)
Excludes13 rule(s)
Excludes20 note(s)
Child codes7

Data Source

CMS ICD-10-CM 2026 Tabular List

Updated October 1, 2025 (FY2026)