ICD-10 Code for Hydrocephalus

The default ICD-10-CM 2027 code for hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) is G91.9 – Hydrocephalus, unspecified. More specific codes depend on the details documented, as listed in the official index (22 codes, 21 billable).

Main code: G91.9 – Hydrocephalus, unspecified
Billable: Yes

Index entries for Hydrocephalus

aqueduct Sylvius stricture – Q03.0
causing disproportion – O33.6 (header)
- with obstructed labor – O66.3
communicating – G91.0
congenital (external) (internal) – Q03.9
- with spina bifida – Q05.4
  - cervical – Q05.0
  - dorsal – Q05.1
  - lumbar – Q05.2
  - lumbosacral – Q05.2
  - sacral – Q05.3
  - thoracic – Q05.1
  - thoracolumbar – Q05.1
- specified NEC – Q03.8
due to toxoplasmosis (congenital) – P37.1
foramen Magendie block (acquired) – G91.1
- congenital – Q03.1 – see also Hydrocephalus, congenital
in (due to)
- infectious disease NEC – B89 – G91.4 [manifestation]
- neoplastic disease NEC (see also Neoplasm) – G91.4
- parasitic disease – B89 – G91.4 [manifestation]
newborn – Q03.9
- with spina bifida – see Spina bifida, with hydrocephalus
noncommunicating – G91.1
normal pressure – G91.2
- secondary – G91.0
obstructive – G91.1
otitic – G93.2
post-traumatic NEC – G91.3
secondary – G91.4
- post-traumatic – G91.3
specified NEC – G91.8
syphilitic, congenital – A50.49

How to choose the right code

Start with the main term, then pick the indented subterm that matches the documentation (type, cause, site, laterality, episode of care). Always confirm the code in the tabular list: follow its Excludes1/Excludes2, “code first” and “use additional code” notes, and add a 7th character where required.

Source: CDC/NCHS ICD-10-CM FY2027 alphabetic index.