G91.3 — Post-traumatic hydrocephalus, unspecified
G91.3 is a billable, specific ICD-10-CM code for post-traumatic hydrocephalus, unspecified. It is valid for submission on a claim.
Excludes1 inherited from the categories above G91.3
These are not written on G91.3, but they bind it: a note on a category applies to every code beneath it. Billing G91.3 with anything listed here is a denial.
Other codes that can never be billed with G91.3
These codes carry an Excludes1 note pointing at G91.3. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading G91.3 alone.
- Q03Congenital hydrocephalus
Risk adjustment
G91.3 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 127 Dementia, Mild or Unspecified0.341 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.
Medicare coverage
G91.3 is named in 4 Medicare coverage policies — 4 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
- A56612Billing and Coding: CT of the Head
- A57204Billing and Coding: MRI and CT Scans of the Head and Neck
- A57780Billing and Coding: Psychological and Neuropsychological Tests
How G91.3 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to G91.3.
- Hydrocephalus›post-traumatic NEC
- Hydrocephalus›secondary›post-traumatic
Code history
G91.3 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share G91. If G91.3 is not quite right, the correct code is usually one of these.
Questions about G91.3
- Is G91.3 a billable ICD-10-CM code?
- Yes. G91.3 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does G91.3 sit in the tabular list?
- Diseases of the nervous system (G00-G99), in the block Other disorders of the nervous system (G89-G99).
- What cannot be coded together with G91.3?
- G91.3 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above G91.3 (G91) and apply to it just the same.