2026 ICD-10-CM Diagnosis Code Q20.9Congenital malformation of cardiac chambers and connections, unspecified

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q20

ICD-10-CM Q20.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q20.9 is a billable ICD-10-CM diagnosis code for congenital malformation of cardiac chambers and connections, 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 congenital abnormality of atrium. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q20.9
Billable Status
Yes — Valid for Submission
Code Describes
Congenital malformation of cardiac chambers and connections, unspecified
Short Description
Congenital malform of cardiac chambers and connections, unsp
Parent Code
Q20
Congenital malformations of cardiac chambers and connections

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ20Congenital malformations of cardiac chambers and connections
This CodeQ20.9Congenital malformation of cardiac chambers and connections, unspecified

Present on Admission (POA)Billing

Q20.9 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.

  • Congenital abnormality of atrium
  • Congenital abnormality of cardiac connection
  • Congenital abnormality of left atrium
  • Congenital abnormality of right atrium
  • Congenital abnormality of ventricles and ventricular septum
  • Congenital anomaly of cardiac chamber
  • Left atrial abnormality

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)
      • cardiac
        • chambers
    • Malformation(congenital)
      • cardiac
        • chambers

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

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 Q20.9 to ICD-9-CMHistory

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

ICD-9-CM
746.9 Cong heart 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 Q20.9Overview

Is Q20.9 (Congenital malformations of cardiac chambers and connections) a billable code?

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

What MS-DRG does Q20.9 group to?

When congenital malformation of cardiac chambers and connections, 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 Q20.9 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 cardiac chambers and connections, unspecified on inpatient claims.

What is the ICD-9 equivalent of Q20.9?

Under the General Equivalence Mappings, congenital malformation of cardiac chambers and connections, unspecified converts to ICD-9-CM 746.9 (cong heart 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.