Q21.1
⚠ Non-billable (Header)Atrial septal defect
Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)
⚠️ This is a category header code — not billable. Use a more specific child code below.
❌ Excludes1
inheritedRules inherited from parent codes in the hierarchy.
- • acquired cardiac septal defect (I51.0)
⚠️ Excludes2
directBoth codes can exist if both conditions are documented.
- • ostium primum atrial septal defect (type I) (Q21.20)
Child Codes (8)
Clinical Description
ICD-10-CM code Q21.1 represents atrial septal defect. This code falls under the Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0) classification. It is a non-billable category header code. A more specific child code from the list below must be used for billing and reimbursement purposes.
This is a 5-character code at the 4th level of specificity. There are 8 more specific child codes under Q21.1. Coders should note that Q21.1 has 1 Excludes1 restriction(s) — codes that cannot be reported together on the same claim.
Frequently Asked Questions
What is ICD-10 code Q21.1?
ICD-10-CM code Q21.1 is "Atrial septal defect". It belongs to the category: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0).
Is Q21.1 a billable ICD-10 code?
No, Q21.1 is a non-billable header code. A more specific child code must be used for billing.
What codes are excluded with Q21.1?
Q21.1 has 1 Excludes1 rule(s). These codes are mutually exclusive and cannot be coded together on the same claim.
Can Q21.1 be coded with other codes?
Q21.1 has 1 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.
Related Codes in Q21
Other codes in the same category that may be relevant for differential coding:
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Data Source
CMS ICD-10-CM 2026 Tabular List
Updated October 1, 2025 (FY2026)