I51.0 vs Q21
I51.0 (Cardiac septal defect, acquired) compared with Q21 (Congenital malformations of cardiac septa), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. Q21 carries an Excludes1 note covering I51.0: “acquired cardiac septal defect (I51.0)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| I51.0Cardiac septal defect, acquired | Q21Congenital malformations of cardiac septa | |
|---|---|---|
| Billing status | Billable | Non-billable header |
| Classification | I00-I99 — Diseases of the Circulatory System (I00-I99) | Q00-Q99 — Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99) |
| Definition | Cardiac septal defect, acquired is a billable ICD-10-CM diagnosis code (I51.0). | Congenital malformations of cardiac septa is a non-billable ICD-10-CM category code (Q21). |
| Includes | Acquired septal atrial defect (old) Acquired septal auricular defect (old) Acquired septal ventricular defect (old) | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources