Q03.1 Atresia of foramina of Magendie and Luschka

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applicable to

• Dandy-Walker syndrome

Applies from Q03 Congenital hydrocephalus

Includes

• hydrocephalus in newborn

Excludes1 (never code together)

• Arnold-Chiari syndrome, type II (Q07.0-)
• acquired hydrocephalus (G91.-)
• hydrocephalus due to congenital toxoplasmosis (P37.1)
• hydrocephalus with spina bifida (Q05.0-Q05.4)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 182 — Spinal Cord Disorders/Injuries
• CMS-HCC V22: HCC 72 — Spinal Cord Disorders/Injuries
• RxHCC V08: HCC 155 — Spinal Cord Disorders
• ESRD V24: HCC 72

MS-DRG index

Defines the logic of DRG(s) 091-093 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 742.3 Congenital hydrocephalus (approximate)

Code annotations containing back-references to Q03.1

Back-references to Q03

• Type 1 Excludes: G91 Hydrocephalus ("congenital hydrocephalus (Q03.-)")
• Type 1 Excludes: Q75 Other congenital malformations of skull and face bones ("hydrocephalus (Q03.-)")

Diagnosis Index entries for Q03.1

• Atresia, atretic › foramen of › Luschka
• Atresia, atretic › foramen of › Magendie
• Block, blocked › foramen Magendie (acquired) › congenital
• Cyst (colloid) (mucous) (simple) (retention) › Dandy-Walker
• Dandy-Walker syndrome
• Deformity › Dandy-Walker
• Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) › foramen Magendie block (acquired) › congenital
• Syndrome › Dandy-Walker

Nearby codes

• Q03 Congenital hydrocephalus
• Q03.0 Malformations of aqueduct of Sylvius
• Q03.1 Atresia of foramina of Magendie and Luschka (this code)
• Q03.8 Other congenital hydrocephalus
• Q03.9 Congenital hydrocephalus, unspecified