FY2027 ICD-10-CM reference
G91: Hydrocephalus
By the HCC Buddy Coding Team
The official ICD-10-CM descriptor is Hydrocephalus. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Nonbillable heading. Verified against the official FY2027 order file.
More specific FY2027 codes
- G91.0: Communicating hydrocephalusBillable code
- G91.1: Obstructive hydrocephalusBillable code
- G91.2: (Idiopathic) normal pressure hydrocephalusBillable code
- G91.3: Post-traumatic hydrocephalus, unspecifiedBillable code
- G91.4: Hydrocephalus in diseases classified elsewhereBillable code
- G91.8: Other hydrocephalusBillable code
- G91.9: Hydrocephalus, unspecifiedBillable code
FY2027 Tabular instructions
Instructions below include applicable chapter, section and parent-code notes. Each note identifies where it appears in the official source.
Excludes2
certain conditions originating in the perinatal period (P04-P96)
Source: G00-G99 (chapter, inherited).
Excludes2
certain infectious and parasitic diseases (A00-B99)
Source: G00-G99 (chapter, inherited).
Excludes2
complications of pregnancy, childbirth and the puerperium (O00-O9A)
Source: G00-G99 (chapter, inherited).
Excludes2
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
Source: G00-G99 (chapter, inherited).
Excludes2
endocrine, nutritional and metabolic diseases (E00-E88)
Source: G00-G99 (chapter, inherited).
Excludes2
injury, poisoning and certain other consequences of external causes (S00-T88)
Source: G00-G99 (chapter, inherited).
Excludes2
neoplasms (C00-D49)
Source: G00-G99 (chapter, inherited).
Excludes2
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: G00-G99 (chapter, inherited).
Includes
acquired hydrocephalus
Source: G91 (category, direct).
Excludes1
Arnold-Chiari syndrome with hydrocephalus (Q07.-)
Source: G91 (category, direct).
Excludes1
congenital hydrocephalus (Q03.-)
Source: G91 (category, direct).
Excludes1
spina bifida with hydrocephalus (Q05.-)
Source: G91 (category, direct).
Compare the FY2027 additions, removals and billable-status changes
What does G91 mean in FY2027?
The official ICD-10-CM descriptor is Hydrocephalus. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Is G91 billable in FY2027?
The FY2027 order file marks G91 as a nonbillable heading. Select a complete billable child code.
Does G91 map to an HCC?
Risk-model mapping is not applicable to this nonbillable heading. Check a complete billable child code.
Source: CMS FY2027 ICD-10-CM order file. Payment model: CMS CY 2027 Rate Announcement. Read the FY2027 Official Guidelines.
Review the FY2026 April edition