Q20.0 vs Q21.4
Q20.0 and Q21.4 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on Q20.0
aortic septal defect (Q21.4)
Q20.0
Common arterial trunk
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q20-Q28
Use when the record says
- Persistent truncus arteriosus
Indexed under
- Common › arterial trunk
- Common › truncus
- Persistence, persistent › truncus arteriosus or communis (congenital)
- Truncus › arteriosus
- Truncus › communis
Q21.4
Aortopulmonary septal defect
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q20-Q28
Use when the record says
- Aortic septal defect
- Aortopulmonary window
Indexed under
- 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
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027