Q21 Congenital malformations of cardiac septa

Not billable (header)Chapter 17

Report one of the more specific codes below.

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Codes under this one

Q21.0 Ventricular septal defect
Q21.1 Atrial septal defectHeader
Q21.2 Atrioventricular septal defectHeader
Q21.3 Tetralogy of Fallot
Q21.4 Aortopulmonary septal defect
Q21.8 Other congenital malformations of cardiac septa
Q21.9 Congenital malformation of cardiac septum, unspecified

Instructional notes

Chapter 17

Excludes2Not included here: the patient may have both; report both when both are present.

inborn errors of metabolism (E70-E88)

Notes

Codes from this chapter are not for use on maternal records

This code

Excludes1Not coded here: never report with this code, except when the two conditions are unrelated.

acquired cardiac septal defect (I51.0)

Chapter 17: Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1) · Q20-Q28 Congenital malformations of the circulatory system (Q20-Q28)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.