G91.4 Hydrocephalus in diseases classified elsewhere
Billable ICD-10-CM code, FY2026.
Excludes1 (never code together)
hydrocephalus due to congenital toxoplasmosis (P37.1)
Code first
underlying condition, such as:
congenital syphilis (A50.4-)
neoplasm (C00-D49)
plasminogen deficiency (E88.02)
Applies from G91 Hydrocephalus
Includes
acquired hydrocephalus
Excludes1 (never code together)
Arnold-Chiari syndrome with hydrocephalus (Q07.-)
congenital hydrocephalus (Q03.-)
spina bifida with hydrocephalus (Q05.-)
Risk adjustment (HCC)
CMS-HCC V28: HCC 127 — Dementia, Mild or Unspecified
ESRD V24: HCC 51
MS-DRG index
Defines the logic of DRG(s) 056-057 in MDC 01.
Approximate ICD-9-CM (GEMs)
331.7 Cerebral degeneration in diseases classified elsewhere (approximate)
Medicare Code Edits (MCE v43.1 (April 2026))
Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.
Code annotations containing back-references to G91.4
Back-references to G91.4
Use Additional: E88.02 Plasminogen deficiency ("hydrocephalus (G91.4)")
Type 1 Excludes: G94 Other disorders of brain in diseases classified elsewhere ("hydrocephalus in diseases classified elsewhere (G91.4)")
Back-references to G91
Type 1 Excludes: Q03 Congenital hydrocephalus ("acquired hydrocephalus (G91.-)")
Diagnosis Index entries for G91.4
Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) › in (due to) › infectious disease NEC
Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) › in (due to) › neoplastic disease NEC (see also Neoplasm)