ICD-10-CM Q21: Congenital malformations of cardiac septa

ICD-10-CM Diagnosis Code (2025)

Official Description for Q21

Congenital malformations of cardiac septa

Coding Notes & Guidelines for Q21

Excludes1: Not Coded Here

acquired cardiac septal defect (I51.0)

Excludes2: Not Included Here

ostium primum atrial septal defect (type I) (Q21.20)

Inclusion Terms

Roger's disease

Inclusion Terms
  • Fenestrated atrial septum
  • Patent or persistent ostium secundum defect (type II)
Inclusion Terms

Persistent foramen ovale

Inclusion Terms
  • Coronary sinus defect
  • Unroofed coronary sinus
Inclusion Terms

Superior vena cava type atrial septal defect

Inclusion Terms

Inferior vena cava type atrial septal defect

Inclusion Terms

Sinus venosus defect, NOS

Inclusion Terms
  • Common atrium
  • Other specified atrial septal abnormality
Inclusion Terms
  • Atrioventricular canal defect
  • Endocardial cushion defect
  • Ostium primum atrial septal defect (type I)
Inclusion Terms
  • Atrioventricular canal, NOS
  • Endocardial cushion defect NOS
  • Ostium primum atrial septal defect (type I) NOS
Inclusion Terms
  • Incomplete atrioventricular canal
  • Incomplete atrioventricular septal defect
  • Incomplete endocardial cushion defect
  • Ostium primum atrial septal defect (type I) with separate atrioventricular valves
  • Partial atrioventricular canal
  • Partial endocardial cushion defect
Inclusion Terms
  • Intermediate atrioventricular canal
  • Intermediate atrioventricular septal defect
  • Intermediate endocardial cushion defect
  • Ostium primum atrial septal defect (type I) with separate atrioventricular valves and a small or restrictive inlet VSD
  • Transitional atrioventricular canal
  • Transitional endocardial cushion defect
Inclusion Terms
  • Common atrioventricular canal
  • Common atrioventricular septal defect
  • Common endocardial cushion defect
  • Ostium primum atrial septal defect (type I) with common atrioventricular valve and a moderate or larger inlet VSD
Inclusion Terms

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

Inclusion Terms
  • Aortic septal defect
  • Aortopulmonary window
Inclusion Terms
  • Eisenmenger's defect
  • Pentalogy of Fallot
Inclusion Terms

Septal (heart) defect NOS

Code Also
  • , if applicable:
  • Eisenmenger's complex (I27.83)
  • Eisenmenger's syndrome (I27.83)

Child Codes (More Specific Codes for Q21):

About ICD-10-CM Code Q21 (Congenital malformations of cardiac septa)

ICD-10-CM code Q21 is a billable or specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. The 2025 edition of ICD-10-CM Q21 became effective on October 1, 2024.

This page provides detailed information about Q21 - Congenital malformations of cardiac septa. It includes common terminology, coding guidelines such as "Includes," "Excludes1," and "Excludes2" notes, and information on required 7th characters. Utilizing this information correctly is essential for accurate medical coding and claims submission for conditions like Congenital malformations of cardiac septa.