2026 ICD-10-CM Diagnosis Code Q21.12Patent foramen ovale

ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q21

ICD-10-CM Q21.12
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q21.12 is a billable ICD-10-CM diagnosis code for patent foramen ovale. 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 fenestrated interatrial communication within oval fossa. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.

Code Identity

ICD-10-CM Code
Q21.12
Billable Status
Yes — Valid for Submission
Code Describes
Patent foramen ovale
Short Description
Patent foramen ovale
Same as the full description in the CMS dataset.
Parent Code
Q21.1
Atrial septal defect

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ20-Q28Congenital malformations of the circulatory system
CategoryQ21Congenital malformations of cardiac septa
This CodeQ21.12Patent foramen ovale

Present on Admission (POA)Billing

Q21.12 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.

  • Fenestrated interatrial communication within oval fossa
  • Nonfenestrated interatrial communication within oval fossa
  • Ostium secundum type atrial septal defect
  • Patent foramen ovale

Tabular List NotesGuidance

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

Inclusion Terms

  • Persistent foramen ovale

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)
      • foramen
        • Botalli
    • Anomaly, anomalous(congenital) (unspecified type)
      • foramen
        • ovale
    • Closure
      • foramen ovale, imperfect
    • Cyanosis
      • due to
        • patent foramen botalli
    • Cyanosis
      • due to
        • persistent foramen ovale
    • Foramen ovale(nonclosure) (patent) (persistent)
    • Imperfect
      • closure (congenital)
        • foramen
          • botalli
    • Imperfect
      • closure (congenital)
        • foramen
          • ovale
    • Nonclosure
      • foramen
        • botalli
    • Nonclosure
      • foramen
        • ovale
    • Patent
      • foramen
        • botalli
    • Patent
      • foramen
        • ovale
    • Persistence, persistent(congenital)
      • foramen
        • Botalli
    • Persistence, persistent(congenital)
      • foramen
        • ovale

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

  • Patent Foramen Ovale

    a persistent opening in the atrial septum after birth. while a normal part of fetal circulation, the foramen ovale should close once the newborn begins breathing and the pressure in the left atrium exceeds that of the right atrium. while a pfo is generally asymptomatic, it can lead to the passage of clots from the venous circulation into the artierial circulation, resulting in paradoxical emboli, and possible strokes.

  • Patent Foramen Ovale Closure|PFO Closure

    repair of a hole in the foramen ovale.

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.

Code History & ChangesHistory

Replacement Q21.12 replaces the following previously assigned code(s):

  • Q21.1 - Atrial septal defect
FY 2023AddedAdded to the ICD-10-CM code setEffective October 1, 2022.
FY 2024–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Q21.12Overview

Is Q21.12 (Atrial septal defect) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report patent foramen ovale on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does Q21.12 group to?

When patent foramen ovale 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 Q21.12 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 patent foramen ovale on inpatient claims.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.