Q21.15 — Inferior sinus venosus atrial septal defect
Is Q21.15 billable?
Yes — Q21.15 is billable for FY2027. Q21.15 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. Q21.15 may be submitted for encounters from October 1, 2026 through September 30, 2027.
Q21.15 at a glance
| Code | Q21.15 |
|---|---|
| Description | Inferior sinus venosus atrial septal defect |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does Q21.15 group to?
Q21.15 sits in MDC 05 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 306Cardiac Congenital and Valvular Disorders with MCCmedical
- 307Cardiac Congenital and Valvular Disorders without MCCmedical
As a secondary diagnosis, Q21.15 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is Q21.15 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to Q21.15. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Defect, defective › atrial septal › sinus venosus › inferior
- Defect, defective › atrial septal › vena cava type › inferior
Inclusion terms
Alternative wording in documentation that is classified to Q21.15.
- Inferior vena cava type atrial septal defect
Excludes1 — never code together — inherited from Q21
The conditions below can never be reported together with Q21.15 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- acquired cardiac septal defect (I51.0)
Excludes2 — not included here — inherited from Chapter 17
The conditions below are not part of Q21.15, but a patient may have both at the same time. When documentation supports it, Q21.15 and the excluded code may both be reported.
- inborn errors of metabolism (E70-E88)
Excludes2 — not included here — inherited from Q21.1
The conditions below are not part of Q21.15, but a patient may have both at the same time. When documentation supports it, Q21.15 and the excluded code may both be reported.
- ostium primum atrial septal defect (type I) (Q21.20)
How long has Q21.15 existed?
Q21.15 first appears in FY2023.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.