2026 ICD-10-CM Diagnosis Code Q28.1Other malformations of precerebral vessels

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q28

ICD-10-CM Q28.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q28.1 is a billable ICD-10-CM diagnosis code for other malformations of precerebral vessels. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 299 through 301. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q28.1
Billable Status
Yes — Valid for Submission
Code Describes
Other malformations of precerebral vessels
Short Description
Other malformations of precerebral vessels
Same as the full description in the CMS dataset.
Parent Code
Q28
Other congenital malformations of circulatory system

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ28Other congenital malformations of circulatory system
This CodeQ28.1Other malformations of precerebral vessels

Present on Admission (POA)Billing

Q28.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Congenital aneurysm of precerebral artery
  • Congenital anomaly of carotid artery
  • Congenital fenestration of basilar artery
  • Congenital hypoplasia of carotid artery
  • Congenital hypoplasia of internal carotid artery
  • Congenital hypoplasia of posterior communicating artery
  • Congenital hypoplasia of vertebral artery
  • Congenital malposition of carotid artery
  • Isolation of common carotid artery
  • Isolation of left common carotid artery
  • Retroesophageal carotid artery

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Congenital malformation of precerebral vessels NOS
  • Congenital precerebral aneurysm (nonruptured)

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Aberrant(congenital)
      • artery (peripheral)
        • basilar NEC
    • Aberrant(congenital)
      • artery (peripheral)
        • precerebral
    • Aberrant(congenital)
      • artery (peripheral)
        • vertebral
    • Aberrant(congenital)
      • vein (peripheral) NEC
        • precerebral
    • Absence(of) (organ or part) (complete or partial)
      • vein (peripheral) congenital NEC
        • precerebral
    • Aneurysm(anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular)
      • precerebral
        • congenital (nonruptured)
    • Anomaly, anomalous(congenital) (unspecified type)
      • artery (peripheral)
        • basilar NEC
    • Anomaly, anomalous(congenital) (unspecified type)
      • artery (peripheral)
        • vertebral NEC
    • Anomaly, anomalous(congenital) (unspecified type)
      • precerebral vessel
    • Anomaly, anomalous(congenital) (unspecified type)
      • vessel (s)
        • precerebral
    • Dissection
      • artery
        • precerebral
          • congenital (nonruptured)
    • Dissection
      • precerebral artery, congenital (nonruptured)
    • Distribution vessel, atypical
      • precerebral
    • Malformation(congenital)
      • precerebral vessels

Clinical ClassificationClinical

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

CCSR MAL001
Cardiac and circulatory congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Arteriovenous Malformations

Arteriovenous malformations (AVMs) are defects in your vascular system. Your vascular system is your body's network of blood vessels. It includes your:

The full article covers:

  • What are arteriovenous malformations (AVMs)?
  • What causes arteriovenous malformations (AVMs)?
  • What are the symptoms of arteriovenous malformations (AVMs)?
  • How are arteriovenous malformations (AVMs) diagnosed?
  • What are the treatments for arteriovenous malformations (AVMs)?

Read the full article at MedlinePlus

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

Convert Q28.1 to ICD-9-CMHistory

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

ICD-9-CM
747.89 Circulatory anomaly NEC
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Q28.1Overview

Is Q28.1 (Other congenital malformations of circulatory system) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other malformations of precerebral vessels on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q28.1 group to?

When other malformations of precerebral vessels is the principal diagnosis on an inpatient stay, it groups to MS-DRG 299, 300, 301, with relative weights from 0.7197 to 1.6327 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q28.1 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 other malformations of precerebral vessels on inpatient claims.

What is the ICD-9 equivalent of Q28.1?

Under the General Equivalence Mappings, other malformations of precerebral vessels converts to ICD-9-CM 747.89 (circulatory anomaly NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.