ICD-10 · PDGM grouping
Q21 Congenital malformations of cardiac septa
All 17 codes in the Q21 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
17
Can lead a claim
16
Cannot lead a claim
1
What CMS assigns to Q21
16 of the 17 codes group to MMTA - Other; 1 is assigned no clinical group. None of the 17 is assigned a comorbidity subgroup. 16 of the 17 can lead a claim.
Every code in Q21
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| Q21.0 | Ventricular septal defect | Can lead a claim | A | None |
| Q21.1 Atrial septal defect | ||||
| Q21.10 | Atrial septal defect, unspecified | Can lead a claim | A | None |
| Q21.11 | Secundum atrial septal defect | Can lead a claim | A | None |
| Q21.12 | Patent foramen ovale | Can lead a claim | A | None |
| Q21.13 | Coronary sinus atrial septal defect | Can lead a claim | A | None |
| Q21.14 | Superior sinus venosus atrial septal defect | Can lead a claim | A | None |
| Q21.15 | Inferior sinus venosus atrial septal defect | Can lead a claim | A | None |
| Q21.16 | Sinus venosus atrial septal defect, unspecified | Can lead a claim | A | None |
| Q21.19 | Other specified atrial septal defect | Can lead a claim | A | None |
| Q21.2 Atrioventricular septal defect | ||||
| Q21.20 | Atrioventricular septal defect, unspecified as to partial or completeCMS: Atrioventricular septal defect, unsp as to part or complete | Can lead a claim | A | None |
| Q21.21 | Partial atrioventricular septal defect | Can lead a claim | A | None |
| Q21.22 | Transitional atrioventricular septal defect | Can lead a claim | A | None |
| Q21.23 | Complete atrioventricular septal defect | Can lead a claim | A | None |
| Q21.3 | Tetralogy of Fallot | Can lead a claim | A | None |
| Q21.4 | Aortopulmonary septal defect | Can lead a claim | A | None |
| Q21.8 | Other congenital malformations of cardiac septa | Can lead a claim | A | None |
| Q21.9 | Congenital malformation of cardiac septum, unspecified | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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