ICD-10 G91
Non-Billable HeaderHydrocephalus
About ICD-10-CM G91
ICD-10-CM code G91 represents Hydrocephalus. This is a non-billable header code in the Nervous System chapter (block G91). The 2026 edition of ICD-10-CM G91 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Type 1 Excludes
Pure excludes, these codes can never be coded together with G91. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- Arnold-Chiari syndrome with hydrocephalus (Q07.-)
- congenital hydrocephalus (Q03.-)
- spina bifida with hydrocephalus (Q05.-)
Includes
- acquired hydrocephalus
Medicare LCD Coverage for G91
Local Coverage Determinations (LCDs) from CMS MACs that list G91 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G91.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but G91 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with G91
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To G91
Other codes in section G89-G99 (Other disorders of the nervous system).
ICD-10 G91, Billing FAQ
Is ICD-10 code G91 billable? +
No, G91 is a non-billable header code. Use a more specific child code from block G91 when submitting claims.
What codes are Type 1 Excludes for G91? +
Type 1 Excludes (never code together with G91): Arnold-Chiari syndrome with hydrocephalus (Q07.-); congenital hydrocephalus (Q03.-); spina bifida with hydrocephalus (Q05.-)
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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