ICD-10-CM
ICD-10 code for Hydrocephalus: G91.9
The ICD-10-CM index points "Hydrocephalus" to G91 (Hydrocephalus), a header that is not billable. When nothing more specific is documented, the billable code is G91.9, Hydrocephalus, unspecified.
Source: CDC ICD-10-CM FY2027 Alphabetic Index file dated June 16, 2026. Publisher page
Run it in Rivvi
Check every code on your export
Upload a claims or problem-list export. Rivvi flags codes that are not billable, replaced, or unspecified when a specific code exists.
Check my exportFree to start. Opens Rivvi, the AI workspace for healthcare teams.
Index subterms
A header groups codes and is not billed. A billable code is one you can report. Listed second marks a billable manifestation code (its CDC title says it is "classified elsewhere"): code the underlying disease or condition first, then this code.
- Q03.0aqueduct Sylvius stricture, Malformations of aqueduct of SylviusBillable
- O33.6causing disproportion, Maternal care for disproportion due to hydrocephalic fetusHeader
- G91.0communicating, Communicating hydrocephalusBillable
- Q03.9congenital (external) (internal), Congenital hydrocephalus, unspecifiedBillable
- P37.1due to toxoplasmosis (congenital), Congenital toxoplasmosisBillable
- G91.1foramen Magendie block (acquired), Obstructive hydrocephalusBillable
- Q03.9newborn, Congenital hydrocephalus, unspecifiedBillable
- G91.1noncommunicating, Obstructive hydrocephalusBillable
- G91.2normal pressure, (Idiopathic) normal pressure hydrocephalusBillable
- G91.1obstructive, Obstructive hydrocephalusBillable
- G93.2otitic, Benign intracranial hypertensionBillable
- G91.3post-traumatic NEC, Post-traumatic hydrocephalus, unspecifiedBillable
- G91.4secondary, Hydrocephalus in diseases classified elsewhereListed second
- G91.8specified NEC, Other hydrocephalusBillable
- A50.49syphilitic, congenital, Other late congenital neurosyphilisBillable
More specific codes in G91
A header groups codes and is not billed. A billable code is one you can report. Listed second marks a billable manifestation code (its CDC title says it is "classified elsewhere"): code the underlying disease or condition first, then this code.
- G91HydrocephalusHeader
- G91.0Communicating hydrocephalusBillable
- G91.1Obstructive hydrocephalusBillable
- G91.2(Idiopathic) normal pressure hydrocephalusBillable
- G91.3Post-traumatic hydrocephalus, unspecifiedBillable
- G91.4Hydrocephalus in diseases classified elsewhereListed second
- G91.8Other hydrocephalusBillable
- G91.9Hydrocephalus, unspecifiedBillable
Excludes1
Excludes1 means these codes are not reported together.
From G91. A note on a category applies to every code under it.
Related conditions
Related pages
- G91.9 code detailsNotes, nearby codes, CMS-HCC group
- Category G91Every code under it
- Chapter 6Diseases of the nervous system
- ICD-10 codes by conditionA to Z
- Check a list of ICD-10 codes
- Denial code CO-11Diagnosis does not support the procedure
- Denial code CO-146Diagnosis invalid for the date of service
- HCPCS Level II code lookup
Questions
What is the ICD-10 code for Hydrocephalus?
The ICD-10-CM index points "Hydrocephalus" to G91 (Hydrocephalus), a header that is not billable. When nothing more specific is documented, the billable code is G91.9, Hydrocephalus, unspecified.
Is G91.9 billable?
Yes. G91.9 is a billable code in the FY2027 ICD-10-CM file. Use a more specific code when the record documents one.
What documentation notes apply to G91.9?
The CDC tabular list gives 3 Excludes1 notes (not coded together) for G91.9 and the categories above it. They are listed on this page.
What chapter is G91.9 in?
Chapter 6. Diseases of the nervous system.
When do ICD-10-CM codes change?
Every October 1, with the new fiscal year file. Some years add April 1 updates. This page uses the FY2027 file, effective October 1, 2026.