2027 ICD-10-CM Diagnosis Code Q28.1Other malformations of precerebral vessels
ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q28
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- POA Exempt
- Chronic Condition
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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 299 through 301. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 30 closely related codes. 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
Code Classification
Present on Admission (POA)Billing
Q28.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the circulatory system (Q20-Q28).
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
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q28.1: its own notes plus those printed at Q28 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.
- Congenital malformation of precerebral vessels NOS
- Congenital precerebral aneurysm (nonruptured)
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 Q28.1, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming Q28.1: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 3
These codes carry an Excludes2 note naming Q28.1: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Aberrant (congenital) See Also: Malposition, congenital;
basilar NEC Q28.1
precerebral Q28.1
vertebral Q28.1
precerebral Q28.1
Anomaly, anomalous (congenital) (unspecified type) Q89.9
basilar NEC Q28.1
vertebral NEC Q28.1
precerebral vessel Q28.1
precerebral Q28.1
Malformation (congenital) See Also: Anomaly;
precerebral vessels Q28.1
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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.
Code HistoryHistory
Questions About Q28.1Overview
What is the ICD-10 code for other malformations of precerebral vessels?
The ICD-10-CM code for other malformations of precerebral vessels is Q28.1 (sometimes written as Q281). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
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 301, 300, 299, with relative weights from 0.7132 to 1.5840 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q28.1 a CC or MCC?
CMS lists Q28.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 30 closely related codes in its exclusion list.
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. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.
