2027 ICD-10-CM Diagnosis Code Q03.0Malformations of aqueduct of Sylvius

ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q03

ICD-10-CM Q03.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q03.0 is a billable ICD-10-CM diagnosis code for malformations of aqueduct of Sylvius. 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 aqueduct of Sylvius anomaly. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.

For Medicare Advantage risk adjustment, Q03.0 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

ICD-10-CM Code
Q03.0
Billable Status
Yes — Valid for Submission
Code Describes
Malformations of aqueduct of Sylvius
Short Description
Malformations of aqueduct of Sylvius
Same as the full description in the CMS dataset.
Parent Code
Q03
Congenital hydrocephalus

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ00-Q07Congenital malformations of the nervous system
CategoryQ03Congenital hydrocephalus
This CodeQ03.0Malformations of aqueduct of Sylvius

Present on Admission (POA)Billing

Q03.0 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

Q03.0 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.

CMS-HCC V28 Category (Payment Model)
HCC 182— Spinal Cord Disorders/Injuries
Payment HCC · PY 2027 one of 251 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.478
community, non-dual, aged · ranges 0.270–0.478 across segments
Hierarchy
Superseded by HCC 180, HCC 181, HCC 191, and HCC 192
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 72
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 72 · ESRD (V21): HCC 72 · ESRD (V24): HCC 72
ESRD V21 weights: 0.102 dialysis, 0.256–0.456 functioning graft · ESRD V24 weights: 0.099 dialysis, 0.222–0.523 functioning graft
Part D (RxHCC)
RxHCC 155 — Spinal Cord Disorders
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Aqueduct of Sylvius anomaly
  • Atresia of aqueduct of Sylvius
  • Congenital obstruction of aqueduct of Sylvius
  • Congenital stenosis of aqueduct of Sylvius
  • Hydrocephalus associated with congenital aqueduct stenosis
  • Hydrocephalus with anomaly of aqueduct of Sylvius
  • Spina bifida with stenosis of aqueduct of Sylvius

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q03.0: 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.

Includes

Further defines, or gives examples of, the content of the category.

From Q03 Congenital hydrocephalus applies to 4 codes
  • hydrocephalus in newborn

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.

  • Anomaly of aqueduct of Sylvius
  • Obstruction of aqueduct of Sylvius, congenital
  • Stenosis of aqueduct of Sylvius

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Q03 Congenital hydrocephalus applies to 4 codes
  • 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)

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.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • inborn errors of metabolism (E70-E88)

Notes

General instructions on how these codes are used.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • 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 Q03.0, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming Q03.0: they are not reported together with it, unless the two conditions are unrelated.

  • G91 Hydrocephalus
    congenital hydrocephalus (Q03.-) names Q03.-, which includes this code
  • Q75 Other congenital malformations of skull and face bones
    hydrocephalus (Q03.-) names Q03.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL004
Nervous system congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Congenital Hydrocephalus

    hydrocephalus that is present at birth.

Patient EducationClinical

Hydrocephalus

Hydrocephalus is the buildup of too much cerebrospinal fluid in the brain. Normally, this fluid cushions your brain. When you have too much, though, it puts harmful pressure on your brain.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Q03.0 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
742.3 Congenital hydrocephalus
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Q03.0Overview

What is the ICD-10 code for malformations of aqueduct of Sylvius?

The ICD-10-CM code for malformations of aqueduct of Sylvius is Q03.0 (sometimes written as Q030). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q03.0 (Congenital hydrocephalus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malformations of aqueduct of Sylvius on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Q03.0 group to?

When malformations of aqueduct of Sylvius 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 Q03.0 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 malformations of aqueduct of Sylvius on inpatient claims. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.

Can Q03.0 be reported with a code from Q07.0?

Not as a rule. The Excludes1 note at Q03, which applies to Q03.0, 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 Q03.0?

Q03.0 (malformations of aqueduct of Sylvius) 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 Q03.0 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, Q03.0 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.