Q21.4 — Aortopulmonary septal defect
Is Q21.4 billable?
Yes — Q21.4 is billable for FY2027. Q21.4 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. Q21.4 may be submitted for encounters from October 1, 2026 through September 30, 2027.
Q21.4 at a glance
| Code | Q21.4 |
|---|---|
| Description | Aortopulmonary septal defect |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does Q21.4 group to?
Q21.4 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
How is Q21.4 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to Q21.4. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Defect, defective › aorticopulmonary septum
- Fenestration, fenestrated › aortico-pulmonary
- Window › aorticopulmonary
- Absence › septum › between aorta and pulmonary artery (of) (organ or part) (complete or partial)
- Agenesis › septum › between aorta and pulmonary artery
- Communication › between › base of aorta and pulmonary artery
- Imperfect › closure › septum › aorticopulmonary
- Imperfect › closure › septum › between aorta and pulmonary artery
Inclusion terms
Alternative wording in documentation that is classified to Q21.4.
- Aortic septal defect
- Aortopulmonary window
Excludes1 — never code together — inherited from Q21
The conditions below can never be reported together with Q21.4 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 Q21.4, but a patient may have both at the same time. When documentation supports it, Q21.4 and the excluded code may both be reported.
- inborn errors of metabolism (E70-E88)
How long has Q21.4 existed?
Q21.4 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with Q21.4?
ICD-10-CM declares these codes mutually exclusive with Q21.4 — exactly one of each pair can be correct for a given encounter.