Anomalies of the fetal aortic arch:: a novel sonographic approach to in-utero diagnosis

Objective To describe a novel, sonographic approach for in-utero evaluation of normal and abnormal aortic arch. Methods Aortic arch was evaluated by imaging of the axial view of the upper fetal mediastinum. The normal left aortic arch was defined by the V-shaped appearance of the junction between the ductus arteriosus and aortic arch, with the trachea situated posteriorly. Right and double aortic arches were diagnosed when the great vessels appeared U-shaped, with intermediate location of the trachea. Results Between 1997 and 1999, 18 347 women were scanned in three prenatal centers, and pathological findings were prospectively recorded. In a retrospective analysis of the records, we identified 19 fetuses (0.1%) with atypical, U-shaped appearance, and no other structural abnormalities present. With the exception of one fetus with a ventricular septal defect, no congenital cardiac defects were present. Right aortic arch was found in 18 cases, while color Doppler made it possible to diagnose one case with double aortic arch, and one fetus was demonstrated as having Kommerell's diverticulum. In all 18 cases, a left descending aorta and left ductus arteriosus were present, the latter coursing to the left of the trachea, forming a loose partial vascular ring. All were asymptomatic at birth and early infancy. The fetus with double aortic arch that had a true vascular ring underwent early infantile correction. Conclusion It is possible to diagnose right and double fetal aortic arch using prenatal ultrasound. The use of color Doppler facilitated in-utero evaluation of possible complications, such as true vascular ring.