2027 ICD-10-CM Diagnosis Code Q21.4Aortopulmonary septal defect
ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q21
- Billable — Valid for Submission
- POA Exempt
- Chronic Condition
Q21.4 is a billable ICD-10-CM diagnosis code for aortopulmonary septal defect. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 306 through 307. The code is exempt from POA reporting. Coders also document this condition as aortopulmonary window. 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
Q21.4 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.
- Aortopulmonary window
- Aortopulmonary window with tubular connection
- Confluent aortopulmonary window with minimal superior and inferior rim
- Distal aortopulmonary window with minimal superior rim
- Endarteritis
- Infective aortitis
- Infective endarteritis at site of aortopulmonary window
- Intermediate aortopulmonary window with adequate superior and inferior rim
- Proximal aortopulmonary window with minimal inferior rim
- Secondary aortitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q21.4: its own notes plus those printed at Q21 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.
- Aortic septal defect
- Aortopulmonary window
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 Q21.4, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming Q21.4: they are not reported together with it, unless the two conditions are unrelated.
- Q20.0 Common arterial trunkaortic septal defect (Q21.4)
Use Additional Code 1
These codes say to use an additional code from the note, and Q21.4 is one of the codes named.
- Q87.88 CTNNB1 syndrome
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Fenestration, fenestrated See Also: Imperfect, closure;
aortico-pulmonary Q21.4
Window See Also: Imperfect, closure;
aorticopulmonary Q21.4
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Aortopulmonary Septal Defect
a developmental abnormality in which the spiral (aortopulmonary) septum failed to completely divide the truncus arteriosus into ascending aorta and pulmonary artery. this abnormal communication between the two major vessels usually lies above their respective valves (aortic valve; pulmonary valve).
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 Q21.4 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q21.4Overview
What is the ICD-10 code for aortopulmonary septal defect?
The ICD-10-CM code for aortopulmonary septal defect is Q21.4 (sometimes written as Q214). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q21.4 (Congenital malformations of cardiac septa) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report aortopulmonary septal defect on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q21.4 group to?
When aortopulmonary septal defect is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9146 to 1.5457 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q21.4 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 aortopulmonary septal defect on inpatient claims. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.
Can Q21.4 be reported with I51.0?
Not as a rule. The Excludes1 note at Q21, which applies to Q21.4, lists "acquired cardiac septal defect (I51.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
