2027 ICD-10-CM Diagnosis Code Q03.1Atresia of foramina of Magendie and Luschka
ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q03
- Billable — Valid for Submission
- Risk Adjusts — HCC 182
- POA Exempt
- Chronic Condition
Q03.1 is a billable ICD-10-CM diagnosis code for atresia of foramina of Magendie and Luschka. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. The code is exempt from POA reporting. Coders also document this condition as congenital anterior polar cataract. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.
For Medicare Advantage risk adjustment, Q03.1 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q03.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the nervous system (Q00-Q07).
Medicare Risk Adjustment (HCC)Billing
Q03.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Congenital anterior polar cataract
- Congenital atresia of foramen of Luschka
- Congenital atresia of foramen of Magendie
- Craniosynostosis with Dandy-Walker malformation and hydrocephalus syndrome
- Dandy-Walker malformation with postaxial polydactyly syndrome
- Dandy-Walker syndrome
- Distal spinal muscular atrophy
- Facial dysmorphism, macrocephaly, myopia, Dandy-Walker malformation syndrome
- Hydrocephalus due to Dandy-Walker malformation
- Spinal muscular atrophy, Dandy-Walker malformation, cataract syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q03.1: its own notes plus those printed at Q03 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Dandy-Walker syndrome
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q03.1, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming Q03.1: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Dandy-Walker syndrome Q03.1
Dandy-Walker Q03.1
Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) G91.9
foramen Magendie block (acquired) G91.1
congenital See Also: Hydrocephalus, congenital; Q03.1
Syndrome See Also: Disease;
Dandy-Walker Q03.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Dandy-Walker Syndrome
a congenital abnormality of the central nervous system marked by failure of the midline structures of the cerebellum to develop, dilation of the fourth ventricle, and upward displacement of the transverse sinuses, tentorium, and torcula. clinical features include occipital bossing, progressive head enlargement, bulging of anterior fontanelle, papilledema, ataxia, gait disturbances, nystagmus, and intellectual compromise. (from menkes, textbook of child neurology, 5th ed, pp294-5)
Patient EducationClinical
Brain Malformations
Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q03.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q03.1Overview
What is the ICD-10 code for atresia of foramina of Magendie and Luschka?
The ICD-10-CM code for atresia of foramina of Magendie and Luschka is Q03.1 (sometimes written as Q031). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q03.1 (Congenital hydrocephalus) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report atresia of foramina of Magendie and Luschka on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q03.1 group to?
When atresia of foramina of Magendie and Luschka is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q03.1 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for atresia of foramina of Magendie and Luschka on inpatient claims. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.
Can Q03.1 be reported with a code from Q07.0?
Not as a rule. The Excludes1 note at Q03, which applies to Q03.1, lists "Arnold-Chiari syndrome, type II (Q07.0-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is Q03.1?
Q03.1 (atresia of foramina of Magendie and Luschka) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does Q03.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q03.1 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
