Q21.3 Tetralogy of Fallot

Billable ICD-10-CM code, FY2026. Acts as a Major Complication or Comorbidity (MCC) as a secondary diagnosis. Exempt from present-on-admission (POA) reporting.

Applicable to

• Ventricular septal defect with pulmonary stenosis or atresia, dextroposition of aorta and hypertrophy of right ventricle.

Applies from Q21 Congenital malformations of cardiac septa

Excludes1 (never code together)

• acquired cardiac septal defect (I51.0)

Risk adjustment (HCC)

• RxHCC V08: HCC 191 — Ventricular Septal Defect and Major Congenital Heart Disorders

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 745.2 Tetralogy of fallot

Code annotations containing back-references to Q21.3

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 Q21.3

• Anomaly, anomalous (congenital) (unspecified type) › heart › septum › interventricular › with pulmonary stenosis or atresia, dextraposition of aorta and hypertrophy of right ventricle
• Anomaly, anomalous (congenital) (unspecified type) › heart › septum › ventricular › with pulmonary stenosis or atresia, dextraposition of aorta and hypertrophy of right ventricle
• Anomaly, anomalous (congenital) (unspecified type) › heart › tetralogy of Fallot
• Defect, defective › interventricular septal › with dextroposition of aorta, pulmonary stenosis and hypertrophy of right ventricle
• Defect, defective › interventricular septal › in tetralogy of Fallot
• Defect, defective › ventricular septal › in tetralogy of Fallot
• Dextraposition, aorta › in tetralogy of Fallot
• Fallot's › tetrad or tetralogy
• Hypertrophy, hypertrophic › ventricle, ventricular (heart) › in tetralogy of Fallot
• Imperfect › closure (congenital) › septum › interventricular › in tetralogy of Fallot
• Imperfect › closure (congenital) › septum › ventricular › with pulmonary stenosis or atresia, dextraposition of aorta, and hypertrophy of right ventricle
• Imperfect › closure (congenital) › septum › ventricular › in tetralogy of Fallot
• Stenosis, stenotic (cicatricial) › pulmonary (artery) (congenital) › with ventricular septal defect, transposition of aorta, and hypertrophy of right ventricle
• Stenosis, stenotic (cicatricial) › pulmonary (artery) (congenital) › in tetralogy of Fallot
• Syndrome › Fallot's
• Tetralogy of Fallot

Nearby codes

• Q21.2 Atrioventricular septal defect
• 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 (this code)
• Q21.4 Aortopulmonary septal defect
• Q21.8 Other congenital malformations of cardiac septa
• Q21.9 Congenital malformation of cardiac septum, unspecified