Alphabetic Index FY2027

G91

Hydrocephalus

FY2027Chapter 6: Diseases of the nervous system/G89–G99 Other disorders of the nervous system

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

G91 is a non-billable ICD-10-CM code category for hydrocephalus. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are G91.0 Communicating hydrocephalus; G91.1 Obstructive hydrocephalus; G91.2 (Idiopathic) normal pressure hydrocephalus; G91.3 Post-traumatic hydrocephalus, unspecified and 3 more. Its coding notes include 3 Excludes1 entries and 8 Excludes2 entries.

Excludes1

Not coded here. The listed conditions generally should not be reported together.

This code
  • Arnold-Chiari syndrome with hydrocephalus (Q07.-)
  • congenital hydrocephalus (Q03.-)
  • spina bifida with hydrocephalus (Q05.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (8 notes)
Inherited from Chapter 6 Diseases of the nervous system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Includes

Further defines or gives examples of the content of the category.

This code
  • acquired hydrocephalus

More specific codes under G91 7