2026 ICD-10-CM Diagnosis Code Q26.9Congenital malformation of great vein, unspecified

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q26

ICD-10-CM Q26.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q26.9 is a billable ICD-10-CM diagnosis code for congenital malformation of great vein, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 306 through 307. The code is exempt from POA reporting. Coders also document this condition as abnormality of right superior vena cava. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q26.9
Billable Status
Yes — Valid for Submission
Code Describes
Congenital malformation of great vein, unspecified
Short Description
Congenital malformation of great vein, unspecified
Same as the full description in the CMS dataset.
Parent Code
Q26
Congenital malformations of great veins

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ26Congenital malformations of great veins
This CodeQ26.9Congenital malformation of great vein, unspecified

Present on Admission (POA)Billing

Q26.9 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.

  • Abnormality of right superior vena cava
  • Anomalies of great veins
  • Congenital abnormality of cardiac vein
  • Congenital abnormality of great cardiac vein
  • Congenital abnormality of great veins and coronary sinus
  • Congenital abnormality of middle cardiac vein
  • Congenital anomaly of inferior vena cava
  • Congenital anomaly of pulmonary veins
  • Congenital anomaly of superior vena cava
  • Congenital anomaly of vena cava

Tabular List NotesGuidance

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

Inclusion Terms

  • Congenital anomaly of vena cava (inferior) (superior) NOS

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.

    • Anomaly, anomalous(congenital) (unspecified type)
      • vein (s) (peripheral)
        • great
    • Anomaly, anomalous(congenital) (unspecified type)
      • vena cava (inferior) (superior)
    • Deformity
      • vein (congenital)
        • great
    • Malformation(congenital)
      • great
        • vein

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

Clinical InformationClinical

  • Congenital Anomaly of Pulmonary Veins

    aberrant drainage of one or more of the pulmonary veins which causes the return of oxygen-rich blood to the right atrium.

Patient EducationClinical

Congenital Heart Defects

Congenital heart defects (CHDs) are problems with the structure of the heart. "Congenital" means that that the problems are present at birth. These defects happen when a fetus's heart doesn't develop normally during pregnancy. Congenital heart defects are the most common type of birth defect.

The full article covers:

  • What are congenital heart defects?
  • What causes congenital heart defects?
  • Who is more likely to have a baby with a congenital heart defect?
  • What are the symptoms of congenital heart defects?
  • What other problems do congenital heart defects cause?
  • How are congenital heart defects diagnosed?
  • What are the treatments for congenital heart defects?

Read the full article at MedlinePlus

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

Convert Q26.9 to ICD-9-CMHistory

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

ICD-9-CM
747.40 Great vein anomaly NOS
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 Q26.9Overview

Is Q26.9 (Congenital malformations of great veins) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report congenital malformation of great vein, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q26.9 group to?

When congenital malformation of great vein, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9132 to 1.5758 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q26.9 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 congenital malformation of great vein, unspecified on inpatient claims.

What is the ICD-9 equivalent of Q26.9?

Under the General Equivalence Mappings, congenital malformation of great vein, unspecified converts to ICD-9-CM 747.40 (great vein anomaly NOS). 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.