Q20.9 Congenital malformation of cardiac chambers and connections, unspecified

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applies from Q20 Congenital malformations of cardiac chambers and connections

Excludes1 (never code together)

• dextrocardia with situs inversus (Q89.3)
• mirror-image atrial arrangement with situs inversus (Q89.3)

MS-DRG index

Defines the logic of DRG(s) 306-307 in MDC 05.

Approximate ICD-9-CM (GEMs)

• 746.9 Unspecified congenital anomaly of heart (approximate)

Code annotations containing back-references to Q20.9

Back-references to Q20

• Code Also: I27.21 Secondary pulmonary arterial hypertension ("congenital heart disease (Q20-Q28)")
• Type 2 Excludes: P29 Cardiovascular disorders originating in the perinatal period ("congenital malformations of the circulatory system (Q20-Q28)")
• Code Also: Z71.87 Encounter for pediatric-to-adult transition counseling ("congenital malformations of the circulatory system (Q20-Q28)")

Diagnosis Index entries for Q20.9

• Anomaly, anomalous (congenital) (unspecified type) › cardiac › chambers
• Malformation (congenital) › cardiac › chambers

Nearby codes

• Q20.3 Discordant ventriculoarterial connection
• Q20.4 Double inlet ventricle
• Q20.5 Discordant atrioventricular connection
• Q20.6 Isomerism of atrial appendages
• Q20.8 Other congenital malformations of cardiac chambers and connections
• Q20.9 Congenital malformation of cardiac chambers and connections, unspecified (this code)