G91
Non-billableHydrocephalus
Hydrocephalus
This is a header/category code. For billing purposes, use a more specific child code from the list below.
Coding Notes
Includes
Conditions included under this code
- acquired hydrocephalus
Excludes 1
Codes that cannot be used together with this code (mutual exclusion)
Excludes 2
Conditions not included here, but the patient may have both
- •certain conditions originating in the perinatal periodP04-P96
- •certain infectious and parasitic diseasesA00-B99
- •complications of pregnancy, childbirth and the puerperiumO9A)O00
- •congenital malformations, deformations, and chromosomal abnormalitiesQ00-Q99
- •endocrine, nutritional and metabolic diseasesE00-E88
- •injury, poisoning and certain other consequences of external causesS00-T88
- •neoplasmsC00-D49
- •symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classifiedR00-R94
Child Codes (7)
G91.0Communicating hydrocephalus
G91.1Obstructive hydrocephalus
G91.2(Idiopathic) normal pressure hydrocephalus
G91.3Post-traumatic hydrocephalus, unspecified
G91.4Hydrocephalus in diseases classified elsewhere
G91.8Other hydrocephalus
G91.9Hydrocephalus, unspecified
ICD-11 Equivalents(1)
ICD-11 Equivalents
View full mappingCorresponding ICD-11 codes from the WHO crosswalk mapping
Also Known As / Clinical Terms(17)
UMLS
- Acquired HydrocephalusC0270716
- Acquired hydrocephalusC0270716
- Acquired hydrocephalus (disorder)C0270716
- Hydrocephalus acquiredC0270716
- acquired hydrocephalusC0270716
- HydrocephalusC0020255
- Hydrocephalus (disorder)C0020255
- Hydrocephalus NOSC0020255
- Hydrocephalus, unspecifiedC0020255
- HydrocephalyC0020255
- Nonsyndromal hydrocephalusC0020255
- Too much cerebrospinal fluid in the brainC0020255
- Water on the brainC0020255
- hydrencephalusC0020255
- hydrencephalyC0020255
- hydrocephalusC0020255
- hydrocephalyC0020255
Frequently Asked Questions
What is the ICD-10 code for hydrocephalus?
The ICD-10-CM code for hydrocephalus is G91. The full clinical description is "Hydrocephalus". G91 is a non-billable header code. Use a more specific child code for billing purposes.
What does ICD-10 code G91 mean?
ICD-10-CM code G91 represents “Hydrocephalus”. It is classified under Chapter 6: Diseases of the Nervous System and is a non-billable header code. Use a more specific child code for billing purposes.
Is G91 a billable code?
No, G91 is a non-billable header code. You need to use one of its more specific child codes for billing. There are 7 child codes under G91.
What chapter is G91 in?
G91 is in Chapter 6: Diseases of the Nervous System (codes G00-G99).
What codes cannot be used with G91?
G91 has Excludes1 notes indicating codes that cannot be used together with it, including: Arnold-Chiari syndrome with hydrocephalus (Q07.-); congenital hydrocephalus (Q03.-); spina bifida with hydrocephalus (Q05.-).
What are the subcategories under G91?
G91 has 7 child codes, including: G91.0 (Communicating hydrocephalus), G91.1 (Obstructive hydrocephalus), G91.2 ((Idiopathic) normal pressure hydrocephalus), G91.3 (Post-traumatic hydrocephalus, unspecified), and 3 more.
What are the UMLS CUIs for G91?
G91 is linked to 2 UMLS Concept Unique Identifiers: C0270716, C0020255. The UMLS (Unified Medical Language System) integrates multiple biomedical vocabularies maintained by the U.S. National Library of Medicine.
How does G91 relate to ICF functioning codes?
ICF (International Classification of Functioning, Disability and Health) codes describe how conditions like hydrocephalus affect a person's functioning — body functions, activities, participation, and environmental factors. AutoICD provides ICF Core Sets for 12+ conditions and can map clinical text to ICF categories automatically. Browse the ICF directory to explore functioning codes.
What is the ICD-11 equivalent of G91?
G91 maps to the ICD-11 code: 8D64.Z (Hydrocephalus, unspecified).
Automate ICD-10 Coding With AI
Send clinical text to the AutoICD API and get back structured ICD-10 codes with confidence scores. Integrates into any EHR or billing system in minutes.
Includes SNOMED Clinical Terms® (SNOMED CT®) used by permission of SNOMED International. Includes content from the UMLS Metathesaurus, courtesy of the U.S. National Library of Medicine.