G91
⚠ Non-billable
Hydrocephalus
ICD-10-CM · FY2026 · Diseases of the Nervous System
Code
G91
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Diseases of the Nervous System
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Official coding notes
From CMS's ICD-10-CM Tabular List.
Includes
- acquired hydrocephalus
Excludes1 — never code together
- Arnold-Chiari syndrome with hydrocephalus (Q07.-)
- congenital hydrocephalus (Q03.-)
- spina bifida with hydrocephalus (Q05.-)
Frequently asked questions
What is ICD-10 code G91?
ICD-10-CM code G91 represents Hydrocephalus. It is a non-billable header code requiring a more specific subcategory in the Diseases of the Nervous System chapter, effective October 1, 2025 – September 30, 2026.
Is G91 billable?
No. G91 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is G91 in?
G91 belongs to the Diseases of the Nervous System chapter (G00–G99) of ICD-10-CM.
Related codes in the G91 category
G91.0
Communicating hydrocephalus
Billable
G91.1
Obstructive hydrocephalus
Billable
G91.2
(Idiopathic) normal pressure hydrocephalus
Billable
G91.3
Post-traumatic hydrocephalus, unspecified
Billable
G91.4
Hydrocephalus in diseases classified elsewhere
Billable
G91.8
Other hydrocephalus
Billable
G91.9
Hydrocephalus, unspecified
Billable
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