To investigate the ultrasonic imaging features of and differential diagnosis methods for the right aortic arch, to analyze the causes of missed diagnosis and misdiagnosis, and to further improve the accuracy of prenatal ultrasound diagnosis.

Cardiac screening examination of the fetus was carried out with views of gray-scale and color Doppler or power Doppler imaging (PDI). When the three-vessel tracheal (3VT) view found that the aortic arch was located in the right of the trachea, the coronary views of the trachea and its branches were obtained to further clarify the relationship among the aortic arch, arterial ductus, and trachea. The sonographic features of 31 cases of fetal right aortic arch were summarized, and the reasons for misdiagnosis were analyzed.

Of the 31 cases of fetal right aortic arch diagnosed by prenatal ultrasound, 20 were alive, 15 were induced, and 6 were lost. As for the results of echocardiography for postpartum children, operation or autopsy were obtained in 31 cases, of which 6 had misdiagnosis or missed diagnosis by prenatal ultrasonography. The coronal views of the trachea and its branches were not obtained in two cases of fetal left aortic arch, and they were misdiagnosed as right aortic arch because the transversely sectioned bronchus were mistaken as the transversely sectioned trachea in the 3VT view. In two cases of right aortic arch with aberrant left subclavian artery, the left common carotid artery was misdiagnosed as a stunted left arch, which resulted in a misdiagnosis as a double aortic arch of the advantage type. In two cases of right aortic arch combined with cardiac defects, right aortic arch was missed in prenatal ultrasound diagnosis. Of 20 children who were followed, 13 were diagnosed with isolated right aortic arch, 2 with combined persistent left superior cavity, 1 with combined 2-3 lumbar vertebral body fusion, and 2 with combined right aortic arch inner or outer non-complex structure abnormality. Follow-up was conducted to the maximum age up to 3 years and 6 months, and 18 of these cases were in good condition and showed no symptoms of respiratory tract compression. One case suffered from complicated intracardiac malformation combined with IDD type congenitally corrected transposition of the great arteries. The child is currently in good condition 11 months after the delivery. One case suffered from combined esophageal atresia and died 14 days after delivery. Chromosome karyotype determination was performed in 6 cases, of whom 5 were normal and 1 was confirmed to have 18-trisomy with severe intracardiac multiple malformation.

The 3VT view is the most important view for diagnosis of right aortic arch of fetus. The accuracy of prenatal ultrasound diagnosis can be improved through the combination of the 3VT view and the coronal view of the trachea and its branches. Simple right aortic arch offers a good prognosis, and the prognosis of right aortic arch with severe ectopic and extracardial malformations depends on the severity of the combined malformation.