G91.1
Obstructive hydrocephalus
Risk-adjusting (HCC)Billable code
HCC risk adjustment mapping
CMS-HCC V28
HCC127
Dementia, Mild or Unspecified
CMS-HCC ESRD V24
HCC51
Dementia With Complications
Coding notes
Excludes 1 never coded together · Excludes 2 may co-exist
Inherited from G91Hydrocephalus
Inherited from chapter 6Diseases of the nervous system
Excludes 2
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)
Official Guidelines for G91.1
FY 2026 ›Find G91.1 in the alphabetic index
9 index paths lead to this code
- Block, blocked › foramen Magendie
- Hydrocephalus › foramen Magendie block
- Hydrocephalus › noncommunicating
- Hydrocephalus › obstructive
- Obstruction, obstructed, obstructive › aqueduct of Sylvius
- Occlusion, occluded › aqueduct of Sylvius
- Occlusion, occluded › ventricle NEC
- Stenosis, stenotic › aqueduct of Sylvius › acquired
- Stricture › aqueduct of Sylvius › acquired