Q21.2 Atrioventricular septal defect

The ICD-10-CM code for Atrioventricular septal defect is Q21.2 (FY2026). It is a non-billable category code — select a more specific code below for claims.

Classification

Chapter

17: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

Section

Q20-Q28: Congenital malformations of the circulatory system (Q20-Q28)

Category Q21

20 codes (17 billable)

FY2026 Status

Stable since FY2024

Inclusion Terms

• Atrioventricular canal defect
• Endocardial cushion defect
• Ostium primum atrial septal defect (type I)

U.S. Hospital Utilization

• An estimated 4,680 U.S. inpatient stays in 2022 included Q21.2 among the documented diagnoses.
• 1,240 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

POA indicator for congenital conditions/anomalies and Q00-Q99 exception

Congenital conditions and anomalies Assign “Y” for congenital conditions and anomalies except for categories Q00- Q99, Congenital anomalies, which are on the exempt list. Congenital conditions are always considered present on admission.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)