ICD-10/G91

G91 ICD 2026 Code: Hydrocephalus

G91 is the authoritative medical code for Hydrocephalus. This classification is used in medical billing and clinical recording to specify the clinical criteria for hydrocephalus (ICD-10-CM G91), ensuring healthcare documentation aligns with 2026 federal coding standards.

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Official Registry Overview & Definition

Hydrocephalus is a non-billable ICD-10-CM category code G91. A more specific billable subcode must be selected for claims submission. Includes: acquired hydrocephalus. Excludes1 (not coded here): Arnold-Chiari syndrome with hydrocephalus Q07.-; congenital hydrocephalus Q03.-; spina bifida with hydrocephalus Q05.-.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for G91 in the official ICD-10-CM tabular list.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • acquired hydrocephalus

Excludes1 — Not Coded Here

Conditions that can never be reported with this code; the two are mutually exclusive.

  • Arnold-Chiari syndrome with hydrocephalus Q07.-
  • congenital hydrocephalus Q03.-
  • spina bifida with hydrocephalus Q05.-

Frequently Asked Questions (FAQ) & Clinical Guidance

Can G91 be billed directly?

No. G91 (Hydrocephalus) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

What can't be coded together with G91?

Per Excludes1 instructions, G91 must not be reported with: Arnold-Chiari syndrome with hydrocephalus (Q07.-); congenital hydrocephalus (Q03.-); spina bifida with hydrocephalus (Q05.-).

Codes in This Family (7)

Official ICD-10-CM classifications in the same code family as G91, with their registry titles.

  • G91.0 — Communicating hydrocephalus
  • G91.1 — Obstructive hydrocephalus
  • G91.2 — (Idiopathic) normal pressure hydrocephalus
  • G91.3 — Post-traumatic hydrocephalus, unspecified
  • G91.4 — Hydrocephalus in diseases classified elsewhere
  • G91.8 — Other hydrocephalus
  • G91.9 — Hydrocephalus, unspecified

Related Codes & Numerical Sequence (Crawl Map)

Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures:

ICD Code G89 Pain, not elsewhere classified
ICD Code G90 Disorders of autonomic nervous system
ICD Code G92 Toxic encephalopathy
ICD Code G93 Other disorders of brain
ICD Code G94 Other disorders of brain in diseases classified elsewhere
ICD Code G95 Other and unspecified diseases of spinal cord
ICD Code G96 Other disorders of central nervous system
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