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    v1.0.28
    OpenPayerBilling CodesCongenital malformations of the circulatory systemICD-10-CM q21-congenital-cardiac-septal-defects
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    ICD-10-CM Code For Congenital Malformations Of Cardiac Septa: Group Overview

    The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group Q21 includes congenital malformations of cardiac septa such as atrial septal defects, ventricular septal defects, and atrioventricular septal defects that disrupt normal intracardiac septation. These ICD-10-CM diagnosis codes are used to document clinical scenarios involving structural septal abnormalities, associated hemodynamic impact, and any related complications or syndromic associations. Accurate coding within the ICD-10-CM Q21 group supports proper claim adjudication, complete clinical documentation, and appropriate reimbursement.

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    ICD-10-CM Q21: Congenital Malformations Of Cardiac Septa Overview

    The ICD-10-CM Q21 group covers congenital defects of the heart septa, including atrial septal defects, ventricular septal defects, and atrioventricular septal defects that impair normal intracardiac blood flow. These conditions affect the structure of the heart within the circulatory system and often present in neonates, infants, or detected later in life. Accurate coding matters for documenting clinical complexity and supporting appropriate reimbursement and care coordination.

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    When to Use

    Use a code from this group when a documented diagnosis identifies a congenital malformation of the cardiac septum such as an atrial septal defect or ventricular septal defect. Select specific codes to reflect laterality, defect type, and any associated complications or syndromic conditions as documented in the medical record.

    ICD-10-CM Codes

    17 rows

    ICD-10-CM CodeDescription
    Q21.0Ventricular septal defect
    Q21.10Atrial septal defect, unspecified
    Q21.11Secundum atrial septal defect
    Q21.12Patent foramen ovale
    Q21.13Coronary sinus atrial septal defect
    Q21.14Superior sinus venosus atrial septal defect
    Q21.15Inferior sinus venosus atrial septal defect
    Q21.16Sinus venosus atrial septal defect, unspecified
    Q21.19Other specified atrial septal defect
    Q21.20Atrioventricular septal defect, unspecified as to partial or complete
    Q21.21Partial atrioventricular septal defect
    Q21.22Transitional atrioventricular septal defect
    Q21.23Complete atrioventricular septal defect
    Q21.3Tetralogy of Fallot
    Q21.4Aortopulmonary septal defect
    Q21.8Other congenital malformations of cardiac septa
    Q21.9Congenital malformation of cardiac septum, unspecified

    DRG Codes

    4 rows

    DRG CodeDescription
    306Cardiac Congenital and Valvular Disorders with MCC
    307Cardiac Congenital and Valvular Disorders without MCC
    791Prematurity with Major Problems
    793Full Term Neonate with Major Problems

    Typical Clinical Scenarios

    • A newborn infant is evaluated in the neonatal unit after a routine prenatal ultrasound suggested a cardiac defect and the baby develops a loud systolic murmur and mild cyanosis in the first 24 hours of life. Echocardiography confirms a communication between the left and right ventricles with left-to-right shunt and no other major cardiac anomalies, prompting assignment of a ventricular septal defect diagnosis. Typical codes: Q21.0
    • A 6-year-old child presents to pediatric cardiology for ongoing follow-up for a previously diagnosed atrial septal defect discovered after recurrent exercise intolerance and frequent respiratory infections; imaging shows a secundum-type defect with right atrial and right ventricular enlargement. The visit documents chronic management planning and surveillance for potential closure, so an atrial septal defect code is assigned to reflect the congenital septal malformation requiring follow-up. Typical codes: Q21.1, Q21.10
    • An adult patient with a history of repaired congenital septal defects in childhood is hospitalized for new onset heart failure symptoms; workup reveals residual or recurrent septal defect with volume overload contributing to heart failure, and the clinician documents the congenital septal malformation as a contributing comorbidity. Typical codes: Q21.2, Q21.9

    Related Codes

    Q20-CONGENITAL-CARDIAC-CHAMBERS-AND-CONNECTIONS

    ICD-10-CM Code For Congenital Malformations Of Cardiac Chambers And Connections: Group Overview

    Q22-CONGENITAL-PULMONARY-TRICUSPID-VALVE

    ICD-10-CM Code For Congenital Malformations Of Pulmonary And Tricuspid Valves: Group Overview

    Q23-CONGENITAL-AORTIC-AND-MITRAL-VALVE-MALFORMATIONS

    ICD-10-CM Code For Congenital Malformations Of Aortic And Mitral Valves: Group Overview

    Q24-OTHER-CONGENITAL-MALFORMATIONS-OF-HEART

    ICD-10-CM Code For Other Congenital Malformations Of Heart: Group Overview

    Q25-CONGENITAL-MALFORMATIONS-OF-GREAT-ARTERIES

    ICD-10-CM Code For Congenital Malformations Of Great Arteries: Group Overview

    Q26-CONGENITAL-MALFORMATIONS-GREAT-VEINS

    ICD-10-CM Code For Congenital Malformations Of Great Veins: Group Overview

    Q27-OTHER-CONGENITAL-PERIPHERAL-VASCULAR-MALFORMATIONS

    ICD-10-CM Code For Other Congenital Malformations Of Peripheral Vascular System: Group Overview

    Q28-OTHER-CONGENITAL-CIRCULATORY-MALFORMATIONS

    ICD-10-CM Code For Other Congenital Malformations Of Circulatory System: Group Overview

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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