Sonographic images of a 23-gestational-week fetus diagnosed with right aortic arch. In the 3VT, the confluence of the DA and aortic arch formed a “U”-like structure, surrounding the trachea and esophagus. This was a characteristic sign of right aortic arch. 3VT, three-vessel-trachea view; DA, ductus arteriosus; E, esophagus; MPA, main pulmonary artery; S, spine; SVC, superior vena cava; T, trachea