ICD-10 Q21.10
Billable / Specific CCAtrial septal defect, unspecified
About ICD-10-CM Q21.10
ICD-10-CM code Q21.10 represents Atrial septal defect, unspecified. This is a billable/specific code in the Congenital Malformations chapter (block Q21). The 2026 edition of ICD-10-CM Q21.10 became effective on October 1, 2025.
Coding Tips for Q21.10
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
Q21.10 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inpatient DRG Impact, CC
codes Atrial septal defect, unspecified. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for Q21.10
Local Coverage Determinations (LCDs) from CMS MACs that list Q21.10 as a covered diagnosis.
Showing top 10 of 287 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing Q21.10.
4 Aetna
1 Cigna
5 Medicare
CPT Codes Commonly Billed with Q21.10
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To Q21.10
Other codes in section Q20-Q28 (Congenital malformations of the circulatory system).
ICD-10 Q21.10, Billing FAQ
Is ICD-10 code Q21.10 billable? +
Yes, Q21.10 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Is Q21.10 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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