ABSTRACT
Aberrant right subclavian artery (ARSA) can be demonstrated in the three vessels and trachea view as a vessel leading from the junction of the aortic arch and the ductus arteriosus, behind the trachea, and toward the right clavicle and shoulder. It is sought by lowering the color Doppler velocity range to 10–15 cm/s. In this plane, it is important not to confuse ARSA with the azygos vein, which appears to course in the direction of the superior vena cava. When ARSA is suspected, its presence can be confirmed by demonstrating arterial flow on pulsed Doppler. If the right subclavian artery has a normal origin, it is found in a plane of the transverse aortic arch that is more cranial than the three vessels and trachea view, and it courses ventrally from the trachea. ARSA is more frequent in trisomy 21 fetuses and in fetuses with other chromosomal aberrations, including microdeletion 22q11.
