Congenitally corrected transposition of the great arteries

Congenitally corrected transposition of the great arteries (cTGA) is an uncommon cardiac malformation characterized by discordant atrioventricular and ventriculoarterial connections. Most cases of cTGA are associated with cardiac anomalies. As the ventricular outflow tract may appear to arise correctly from the right and left ventricles, cases of cTGA with a mild associated anomaly are rarely detected prenatally. Parallel vessels are evident in cTGA, but this sign is also present in complete TGA. We report a case of cTGA diagnosed in utero at 29 weeks' gestation. The fetus was diagnosed as TGA and referred to our hospital at 28 weeks' gestation. cTGA was found at 29 weeks' gestation in our hospital, and no additional cardiac anomalies were seen prenatally. After birth, patent ductus arteriosus with bidirectional flow was present. Careful examination of the four-chamber view suggested atrioventricular discordance. Identification of a parallel course of the great vessels, with the aorta anterior and to the left of the pulmonary trunk (l-transposition), may help accurate prenatal diagnosis of cTGA.