Q23.0 vs Q23.4
Q23.0 (Congenital stenosis of aortic valve) compared with Q23.4 (Hypoplastic left heart syndrome), 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. Q23.0 carries an Excludes1 note covering Q23.4: “congenital stenosis of aortic valve in hypoplastic left heart syndrome (Q23.4)”
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
| Q23.0Congenital stenosis of aortic valve | Q23.4Hypoplastic left heart syndrome | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | Q00-Q99 — Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99) | Q00-Q99 — Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99) |
| Definition | Congenital stenosis of aortic valve is a billable ICD-10-CM diagnosis code (Q23.0). | Hypoplastic left heart syndrome is a billable ICD-10-CM diagnosis code (Q23.4). |
| Includes | Congenital aortic atresia Congenital aortic stenosis NOS | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources