Q21.4 — Aortopulmonary septal defect
Q21.4 is a billable, specific ICD-10-CM code for aortopulmonary septal defect. It is valid for submission on a claim.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Aortic septal defect
- Aortopulmonary window
Other codes that can never be billed with Q21.4
These codes carry an Excludes1 note pointing at Q21.4. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading Q21.4 alone.
- Q20.0Common arterial trunk
Risk adjustment
Q21.4 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
Q21.4 is named in 19 Medicare coverage policies — 19 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A52850Billing and Coding: Cardiac Catheterization and Coronary Angiography
- A54111Billing and Coding: Speech Language Pathology (SLP) Services: Communication Disorders
- A56451Billing and Coding: Cardiac Computed Tomography (CCT) and Coronary Computed Tomography Angiography (CCTA)
- A56476Billing and Coding: Cardiac Radionuclide Imaging
How Q21.4 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to Q21.4.
- Defect, defective›aorticopulmonary septum
- Fenestration, fenestrated›aortico-pulmonary
- Window›aorticopulmonary
- Absence›septum›between aorta and pulmonary artery
- 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
Related codes at this level
Codes that share Q21. If Q21.4 is not quite right, the correct code is usually one of these.
Questions about Q21.4
- Is Q21.4 a billable ICD-10-CM code?
- Yes. Q21.4 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does Q21.4 sit in the tabular list?
- Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0), in the block Congenital malformations of the circulatory system (Q20-Q28).