G91.1
BillableObstructive hydrocephalus
HCC Category Mapping
V28HCC 127 — Dementia, Mild or Unspecified
0.464What This Code Means
Obstructive hydrocephalus occurs when cerebrospinal fluid accumulates in the brain due to a blockage preventing normal fluid circulation and absorption.
Coding Tips
- •Identify and document the cause of obstruction (tumor, stenosis, malformation) if known
- •Imaging should confirm ventricular enlargement with evidence of blocked flow pathways
Clinical Significance
Obstructive hydrocephalus results from physical blockage of cerebrospinal fluid flow within the ventricular system, often caused by tumors, congenital malformations, or acquired lesions. This is typically more acute and clinically urgent than communicating hydrocephalus, often requiring emergent neurosurgical intervention. The underlying cause of obstruction must be identified and addressed, making this a high-complexity diagnosis.
Documentation Requirements
- ✓Neuroimaging (CT or MRI) demonstrating ventricular dilation with identifiable point of obstruction
- ✓Identification of the obstructing lesion or cause (tumor, cyst, congenital stenosis, hemorrhage)
- ✓Clinical signs and symptoms of increased intracranial pressure (headache, nausea/vomiting, papilledema, altered consciousness)
- ✓Surgical intervention details if applicable (shunt placement, endoscopic third ventriculostomy, tumor resection)
- ✓Follow-up plan including imaging surveillance for shunt function or recurrence
Commonly Confused Codes
G91.0 — Communicating hydrocephalus: CSF absorption is impaired but flow pathways remain openG91.4 — Hydrocephalus in diseases classified elsewhere: when hydrocephalus is manifestation of a classified underlying diseaseQ03.0 — Malformations of aqueduct of Sylvius: congenital aqueductal stenosis, use for congenital formsG91.2 — Normal pressure hydrocephalus: chronic condition with normal opening pressures on lumbar puncture