FY2027
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ICD-10 Code for Hydrocephalus

Also indexed as (acquired) (external) (internal) (malignant) (recurrent)

The ICD-10-CM code for hydrocephalus is G91.9 — Hydrocephalus, unspecified. This is the code the Alphabetic Index gives for hydrocephalus with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).

BillableUnspecified

G91.9 is billable but unspecified. If the documentation names a type, site or cause, one of the more specific codes below is likely expected.

Which hydrocephalus code should you use?

The Alphabetic Index lists 22 codes under Hydrocephalus. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.

By type

aqueduct Sylvius strictureQ03.0Malformations of aqueduct of Sylvius
causing disproportionO33.6Not billableMaternal care for disproportion due to hydrocephalic fetus
communicatingG91.0Communicating hydrocephalus
congenitalQ03.9Congenital hydrocephalus, unspecified
due to toxoplasmosisP37.1Congenital toxoplasmosis
foramen Magendie blockG91.1Obstructive hydrocephalus
newbornQ03.9Congenital hydrocephalus, unspecified
noncommunicatingG91.1Obstructive hydrocephalus
normal pressureG91.2(Idiopathic) normal pressure hydrocephalus
obstructiveG91.1Obstructive hydrocephalus
otiticG93.2Benign intracranial hypertension
post-traumatic NECG91.3Post-traumatic hydrocephalus, unspecified
secondaryG91.4Hydrocephalus in diseases classified elsewhere
specified NECG91.8Other hydrocephalus
syphilitic, congenitalA50.49Other late congenital neurosyphilis

Hydrocephalus causing disproportion

with obstructed laborO66.3Obstructed labor due to other abnormalities of fetus

Hydrocephalus congenital

with spina bifidaQ05.4Unspecified spina bifida with hydrocephalus
specified NECQ03.8Other congenital hydrocephalus
with spina bifida › cervicalQ05.0Cervical spina bifida with hydrocephalus
with spina bifida › dorsalQ05.1Thoracic spina bifida with hydrocephalus
with spina bifida › lumbarQ05.2Lumbar spina bifida with hydrocephalus
with spina bifida › lumbosacralQ05.2Lumbar spina bifida with hydrocephalus
with spina bifida › sacralQ05.3Sacral spina bifida with hydrocephalus
with spina bifida › thoracicQ05.1Thoracic spina bifida with hydrocephalus
with spina bifida › thoracolumbarQ05.1Thoracic spina bifida with hydrocephalus

Hydrocephalus foramen Magendie block

congenitalQ03.1Atresia of foramina of Magendie and Luschka

Hydrocephalus in

infectious disease NECB89Unspecified parasitic disease
neoplastic disease NECG91.4Hydrocephalus in diseases classified elsewhere
parasitic diseaseB89Unspecified parasitic disease

Hydrocephalus normal pressure

secondaryG91.0Communicating hydrocephalus

Hydrocephalus secondary

post-traumaticG91.3Post-traumatic hydrocephalus, unspecified

Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources