2026 ICD-10-CM Diagnosis Code Q26.4Anomalous pulmonary venous connection, unspecified

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q26

ICD-10-CM Q26.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q26.4 is a billable ICD-10-CM diagnosis code for anomalous pulmonary venous connection, 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q26.4
Billable Status
Yes — Valid for Submission
Code Describes
Anomalous pulmonary venous connection, unspecified
Short Description
Anomalous pulmonary venous connection, 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 CodeQ26.4Anomalous pulmonary venous connection, unspecified

Present on Admission (POA)Billing

Q26.4 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.

  • Abnormal inferior vena caval connection
  • Anomalous pulmonary to systemic collateral vein
  • Anomalous pulmonary venous connection of mixed type
  • Anomalous pulmonary venous connection of mixed type with two pulmonary venous confluences
  • Anomalous pulmonary venous drainage
  • Anomalous pulmonary venous drainage to abdominal portion of inferior vena cava
  • Anomalous pulmonary venous drainage to coronary sinus
  • Anomalous pulmonary venous drainage to hepatic veins
  • Anomalous pulmonary venous drainage to right atrium
  • Anomalous pulmonary venous drainage to superior vena cava
  • Anomalous termination of right pulmonary vein
  • Congenital abnormality of hepatic vein
  • Congenital hypoplasia of pulmonary artery
  • Congenital hypoplasia of right side of chest
  • Congenital pulmonary vein confluence
  • Cor triatriatum with some pulmonary veins to proximal chamber draining to left atrium
  • Cor triatriatum with some pulmonary veins to proximal chamber draining to right atrium and others connecting directly to left atrium
  • Divided left atrium with some pulmonary veins to proximal chamber
  • Divided left atrium with some pulmonary veins to proximal chamber draining to left atrium and others connecting directly to left atrium
  • Divided left atrium with some pulmonary veins to proximal chamber draining to right atrium
  • Divided left atrium with some pulmonary veins to proximal chamber draining to right atrium and others connecting anomalously
  • Infracardiac location of anomalous pulmonary venous connection
  • Infracardiac location of anomalous pulmonary venous connection to hepatic vein
  • Infracardiac location of anomalous pulmonary venous connection to patent venous duct
  • Infracardiac location of anomalous pulmonary venous connection with two descending veins
  • Infracardiac location of anomalous pulmonary venous connections to inferior caval vein
  • Infracardiac location of anomalous pulmonary venous connections to portal system
  • Intracardiac location of anomalous pulmonary venous connection
  • Intracardiac location of anomalous pulmonary venous connection to coronary sinus
  • Intracardiac location of anomalous pulmonary venous connection to midline with isomeric atria
  • Intracardiac location of anomalous pulmonary venous connection to right atrium
  • Intracardiac location of anomalous pulmonary venous connections to bilateral isomeric atriums
  • Obstructed pulmonary venous connection
  • Obstructed pulmonary venous connection at coronary sinus orifice
  • Pulmonary vein atresia
  • Pulmonary venous confluence in direct proximity to left atrium
  • Pulmonary venous confluence in horizontal orientation
  • Pulmonary venous confluence in vertical orientation
  • Pulmonary venous confluence remote from left atrium
  • Scimitar syndrome
  • Scimitar syndrome with additional anomalous pulmonary venous connection
  • Supracardiac location of anomalous pulmonary venous connection
  • Supracardiac location of anomalous pulmonary venous connection to azygos vein
  • Supracardiac location of anomalous pulmonary venous connection to hemiazygos vein
  • Supracardiac location of anomalous pulmonary venous connection to left sided vertical vein
  • Supracardiac location of anomalous pulmonary venous connection to left superior caval vein
  • Supracardiac location of anomalous pulmonary venous connection to right sided vertical vein
  • Supracardiac location of anomalous pulmonary venous connection to right superior caval vein
  • Transposition of pulmonary veins

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)
      • connection
        • pulmonary venous
    • Anomaly, anomalous(congenital) (unspecified type)
      • opening, pulmonary veins
    • Anomaly, anomalous(congenital) (unspecified type)
      • pulmonary
        • venous connection
    • Atresia, atretic
      • vein NEC
        • pulmonary
    • Malformation(congenital)
      • great
        • vein
          • anomalous
            • pulmonary venous connection

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

  • Scimitar Syndrome

    an anomalous pulmonary venous return in which the right pulmonary vein is not connected to the left atrium but to the inferior vena cava. scimitar syndrome is named for the crescent- or turkish sword-like shadow in the chest radiography and is often associated with hypoplasia of the right lung and right pulmonary artery, and dextroposition of the heart.

  • Scimitar Syndrome

    a rare congenital cardiopulmonary defect characterized by abnormal right-sided pulmonary venous drainage and right lung malformations.

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 Q26.4 to ICD-9-CMHistory

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

ICD-9-CM
747.42 Part anom pulm ven conn
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 Q26.4Overview

Is Q26.4 (Congenital malformations of great veins) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report anomalous pulmonary venous connection, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q26.4 group to?

When anomalous pulmonary venous connection, 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 Q26.4 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 anomalous pulmonary venous connection, unspecified on inpatient claims.

What is the ICD-9 equivalent of Q26.4?

Under the General Equivalence Mappings, anomalous pulmonary venous connection, unspecified converts to ICD-9-CM 747.42 (part anom pulm ven conn). 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.