[Diagnosis of isolated fetal aberrant right subclavian artery]

A case of a fetal isolated aberrant right subclavian artery (ARSA) diagnosis and discuss its clinical implications and the methodology used to assess the fetal right subclavian artery by transabdominal ultrasound in normal cases and those with ARSA is reported.

A 35-year-old pregnant woman in her twentieth week of pregnancy was evaluated at our Fetal Medicine Unit. An isolated ARSA was detected by a transabdominal ultrasound scan of the fetus. The visualization of this anomaly was achieved through an axial view of the fetal thorax, at the level of the three vessels and trachea scanning plane. It was observed that the origin of ARSA from the aortic arch was close to the ductus arteriosus and it followed a retrotracheal course towards the right arm. The described methodology used to assess the right subclavian artery could be useful for prenatal diagnosis in cases of ARSA. Based on this protocol, further studies could be performed to evaluate the utility of ARSA as a sonographic marker for chromosomal abnormality and congenital heart disease. After the diagnosis of an isolated ARSA, the performance of a fetal karyotype test is still debatable.