Q21.21 Partial atrioventricular septal defect

The ICD-10-CM code for Partial atrioventricular septal defect is Q21.21 (FY2026). It is a billable, claim-ready diagnosis code.

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

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Q21.21:

• Incomplete › endocardial cushion defect
• Incomplete › atrioventricular › canal
• Defect, defective › cushion, endocardial › incomplete
• Canal › atrioventricular › partial
• Canal › atrioventricular › incomplete
• Incomplete › atrioventricular › septal defect
• Defect, defective › atrioventricular › septal › partial
• Defect, defective › atrioventricular › septal › incomplete

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

U.S. Hospital Utilization

• An estimated 700 U.S. inpatient stays in 2023 included Q21.21 among the documented diagnoses.
• 260 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)

Cite This Page

Reference Q21.21 with the canonical source and edition:

Q21.21 — Partial atrioventricular septal defect. ICD-10 Coding Pro (ICD-10-CM FY2026). https://icd10codingpro.com/codes/Q21.21

Canonical URL: https://icd10codingpro.com/codes/Q21.21