Q21.1Atrial septal defect

Q21.1 is the ICD-10-CM diagnosis code for atrial septal defect. It belongs to category Q21 (congenital malformations of cardiac septa), block Q20-Q28 (congenital malformations of the circulatory system) and chapter 17 (congenital malformations, deformations, chromosomal abnormalities, and genetic disorders). It is a header code, so it can't be reported by itself; one of its 8 subcodes must be used instead.

Within Q21 (congenital malformations of cardiac septa), Q21.1 is specifically for atrial septal defect. Related codes cover ventricular septal defect (Q21.0), atrioventricular septal defect (Q21.2), tetralogy of Fallot (Q21.3), Aortopulmonary septal defect (Q21.4), other congenital malformations of cardiac septa (Q21.8) and congenital malformation of cardiac septum, unspecified (Q21.9).

To report this condition, pick the subcode that matches the documentation: Q21.10 (unspecified), Q21.11 (defect), Q21.12 (ovale), Q21.13 (defect), Q21.14 (defect), Q21.15 (defect), Q21.16 (unspecified) and Q21.19 (defect).

The conditions in its Excludes2 note aren't part of Q21.1, but may be coded alongside it if the patient has both: ostium primum atrial septal defect (type I) (Q21.20).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015, and changed in FY2023 (expanded into subcodes).

Before ICD-10, this condition was coded in ICD-9-CM as 745.5 (ostium secundum type atrial septal defect).