DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

Q21 Congenital malformations of cardiac septa

  • Header · not billable

Q21 is not billable. The category heads 17 billable codes in FY2027, grouped under 7 subdivisions.

Index → code

Where it sits

  1. Chapter 17 Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA1)
  2. Q20-Q28 Congenital malformations of the circulatory system (Q20-Q28)
  3. Q21 Congenital malformations of cardiac septa
Billable codes
17
Subdivisions
7
CC / MCC codes
13 / 1
HCC V28 codes
0
New FY2027
0
Index entries
168

Codes in Q21

  1. Q21.0
    Ventricular septal defect
    BillableCCExempt
    Inclusion terms 1

    Inclusion terms

    • Roger's disease
  2. Q21.1
    Atrial septal defect
    Header
    Excludes2 1

    Excludes2

    • ostium primum atrial septal defect (type I) (Q21.20) Q21.20
  3. Q21.10
    Atrial septal defect, unspecified
    BillableCCExempt
  4. Q21.11
    Secundum atrial septal defect
    BillableCCExempt
    Inclusion terms 2

    Inclusion terms

    • Fenestrated atrial septum
    • Patent or persistent ostium secundum defect (type II)
  5. Q21.12
    Patent foramen ovale
    BillableCCExempt
    Inclusion terms 1

    Inclusion terms

    • Persistent foramen ovale
  6. Q21.13
    Coronary sinus atrial septal defect
    BillableCCExempt
    Inclusion terms 2

    Inclusion terms

    • Coronary sinus defect
    • Unroofed coronary sinus
  7. Q21.14
    Superior sinus venosus atrial septal defect
    BillableCCExempt
    Inclusion terms 1

    Inclusion terms

    • Superior vena cava type atrial septal defect
  8. Q21.15
    Inferior sinus venosus atrial septal defect
    BillableCCExempt
    Inclusion terms 1

    Inclusion terms

    • Inferior vena cava type atrial septal defect
  9. Q21.16
    Sinus venosus atrial septal defect, unspecified
    BillableCCExempt
    Inclusion terms 1

    Inclusion terms

    • Sinus venosus defect, NOS
  10. Q21.19
    Other specified atrial septal defect
    BillableCCExempt
    Inclusion terms 2

    Inclusion terms

    • Common atrium
    • Other specified atrial septal abnormality
  11. Q21.2
    Atrioventricular septal defect
    Header
    Inclusion terms 3

    Inclusion terms

    • Atrioventricular canal defect
    • Endocardial cushion defect
    • Ostium primum atrial septal defect (type I)
  12. Q21.20
    Atrioventricular septal defect, unspecified as to partial or complete
    BillableCCExempt
    Inclusion terms 3

    Inclusion terms

    • Atrioventricular canal, NOS
    • Endocardial cushion defect NOS
    • Ostium primum atrial septal defect (type I) NOS
  13. Q21.21
    Partial atrioventricular septal defect
    BillableCCExempt
    Inclusion terms 6

    Inclusion terms

    • Incomplete atrioventricular canal
    • Incomplete atrioventricular septal defect
    • Incomplete endocardial cushion defect
    • Ostium primum atrial septal defect (type I) with separate atrioventricular valves
    • Partial atrioventricular canal
    • Partial endocardial cushion defect
  14. Q21.22
    Transitional atrioventricular septal defect
    BillableCCExempt
    Inclusion terms 6

    Inclusion terms

    • Intermediate atrioventricular canal
    • Intermediate atrioventricular septal defect
    • Intermediate endocardial cushion defect
    • Ostium primum atrial septal defect (type I) with separate atrioventricular valves and a small or restrictive inlet VSD
    • Transitional atrioventricular canal
    • Transitional endocardial cushion defect
  15. Q21.23
    Complete atrioventricular septal defect
    BillableCCExempt
    Inclusion terms 4

    Inclusion terms

    • Common atrioventricular canal
    • Common atrioventricular septal defect
    • Common endocardial cushion defect
    • Ostium primum atrial septal defect (type I) with common atrioventricular valve and a moderate or larger inlet VSD
  16. Q21.3
    Tetralogy of Fallot
    BillableMCCExempt
    Inclusion terms 1

    Inclusion terms

    • Ventricular septal defect with pulmonary stenosis or atresia, dextroposition of aorta and hypertrophy of right ventricle.
  17. Q21.4
    Aortopulmonary septal defect
    BillableExempt
    Inclusion terms 2

    Inclusion terms

    • Aortic septal defect
    • Aortopulmonary window
  18. Q21.8
    Other congenital malformations of cardiac septa
    BillableExempt
    Inclusion terms 2, Code also 3

    Inclusion terms

    • Eisenmenger's defect
    • Pentalogy of Fallot

    Code also

    • , if applicable:
    • Eisenmenger's complex (I27.83) I27.83
    • Eisenmenger's syndrome (I27.83) I27.83
  19. Q21.9
    Congenital malformation of cardiac septum, unspecified
    BillableExempt
    Inclusion terms 1

    Inclusion terms

    • Septal (heart) defect NOS

CC/MCC: as a secondary diagnosis, unless the principal diagnosis is on the code’s PDX exclusion list (MS-DRG v44 Appendix C; list on the code card).

Sources of each column.

Instructions

At Q21

Excludes1

  • acquired cardiac septal defect (I51.0) I51.0

Notes that also apply

Chapter 17 instructions (Notes 1, Excludes2 1): printed on the chapter 17 page.

Index entries

  • Gerbode defect → Q21.0
  • Maladie de Roger → Q21.0
  • Roger's disease → Q21.0
  • Foramen ovale (nonclosure) (patent) (persistent) → Q21.12
  • Unroofed coronary sinus → Q21.13
  • Acleistocardia → Q21.19
  • Lutembacher's disease or syndrome (atrial septal defect with mitral stenosis) → Q21.19
  • Tetralogy of Fallot → Q21.3
  • Bulbus cordis (left ventricle) (persistent) → Q21.8
  • Pentalogy of Fallot → Q21.8
  • Anomaly, anomalous (congenital) (unspecified type)Gerbode → Q21.0
  • Closureinterventricular septum, defective → Q21.0
  • Defect, defectivebulbar septum → Q21.0
  • Defect, defectiveGerbode → Q21.0
  • Defect, defectiveinterventricular septal → Q21.0
  • Defect, defectiveventricular septal → Q21.0
  • Disease, diseasedRoger's (congenital interventricular septal defect) → Q21.0
  • Displacement, displacedventricular septum → Q21.0
  • Fusion, fused (congenital)ventricles, heart → Q21.0
  • Imperfectseptum, ventricular → Q21.0
  • Patentinterventricular septum → Q21.0
  • Defect, defectiveatrial septal → Q21.10
  • Defect, defectiveauricular septal → Q21.10
  • Deformityatrial septal → Q21.10
  • Fenestration, fenestratedatrial septum → Q21.11
  • Ostiumsecundum (arteriosum) (defect) (patent) (persistent) → Q21.11
  • Patentostium secundum (type II) → Q21.11
  • Closureforamen ovale, imperfect → Q21.12
  • Defect, defectivecoronary sinus → Q21.13
  • Abnormal, abnormality, abnormalitiessinus venosus → Q21.16
  • Defect, defectivesinus venosus → Q21.16
  • Abnormal, abnormality, abnormalitiesatrial septal, specified NEC → Q21.19
  • Absence (of) (organ or part) (complete or partial)atrial septum (congenital) → Q21.19
  • Closureinterauricular septum, defective → Q21.19
  • Commonatrium → Q21.19
  • Defect, defectiveinteratrial septal → Q21.19
  • Defect, defectiveinterauricular septal → Q21.19
  • Disease, diseasedLutembacher's (atrial septal defect with mitral stenosis) → Q21.19
  • Fusion, fused (congenital)atria → Q21.19
  • Fusion, fused (congenital)auricles, heart → Q21.19

128 more, longer entries are not listed; the search box finds them by word.

NCHS Alphabetic Index. Index first, then the Tabular List.

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