Q21.4 Aortopulmonary septal defect

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applicable to

• Aortic septal defect
• Aortopulmonary window

Applies from Q21 Congenital malformations of cardiac septa

Excludes1 (never code together)

• acquired cardiac septal defect (I51.0)

MS-DRG index

Defines the logic of DRG(s) 306-307 in MDC 05.

Approximate ICD-9-CM (GEMs)

• 745.8 Other bulbus cordis anomalies and anomalies of cardiac septal closure (approximate)

Code annotations containing back-references to Q21.4

Back-references to Q21.4

• Type 1 Excludes: Q20.0 Common arterial trunk ("aortic septal defect (Q21.4)")

Back-references to Q21

• Code Also: I27.21 Secondary pulmonary arterial hypertension ("congenital heart disease (Q20-Q28)")
• Type 2 Excludes: P29 Cardiovascular disorders originating in the perinatal period ("congenital malformations of the circulatory system (Q20-Q28)")
• Code Also: Q87.85 MED13L syndrome ("congenital malformations of cardiac septa (Q21.-)")
• Code Also: Z71.87 Encounter for pediatric-to-adult transition counseling ("congenital malformations of the circulatory system (Q20-Q28)")

Diagnosis Index entries for Q21.4

• Absence (of) (organ or part) (complete or partial) › septum › between aorta and pulmonary artery
• Agenesis › septum › between aorta and pulmonary artery
• Communication › between › base of aorta and pulmonary artery
• Defect, defective › aorticopulmonary septum
• Fenestration, fenestrated › aortico-pulmonary
• Imperfect › closure (congenital) › septum › aorticopulmonary
• Imperfect › closure (congenital) › septum › between aorta and pulmonary artery
• Window › aorticopulmonary

Nearby codes

• Q21.20 Atrioventricular septal defect, unspecified as to partial or complete
• Q21.21 Partial atrioventricular septal defect
• Q21.22 Transitional atrioventricular septal defect
• Q21.23 Complete atrioventricular septal defect
• Q21.3 Tetralogy of Fallot
• Q21.4 Aortopulmonary septal defect (this code)
• Q21.8 Other congenital malformations of cardiac septa
• Q21.9 Congenital malformation of cardiac septum, unspecified