Aberrant right subclavian artery: the importance of distinguishing between isolated and non-isolated cases in prenatal diagnosis and clinical management.

Objectives: This study aimed to evaluate the association of aberrant right subclavian artery (ARSA) with genetic abnormalities and postnatal symptomatology, by comparing isolated and non-isolated ARSA cases.

Methods: Retrospective, descriptive and comparative study involving fetuses diagnosed with ARSA during routine fetal ultrasound scans, between 19 and 40 weeks, in a tertiary referral university hospital in Barcelona from January 2007 to December 2023.

Results: Out of 154 fetuses diagnosed with ARSA, 75.3 % (116) were classified as isolated cases, while 24.7 % (38) had associated structural anomalies. Non-invasive prenatal testing with cell-free DNA was performed in 27.3 % (42) of cases, yielding low-risk results in 96.6 %, with only one case of trisomy 21 detected. Genetic evaluation was pursued in 15.6 % (24) of cases, revealing abnormalities in three fetuses: one with trisomy 21 and two with 22q11 deletion. All affected fetuses had associated structural defects. Overall, 151 fetuses survived after birth, there were two terminations of pregnancy and one stillbirth. Mild symptoms at birth were observed in 1.9 % (3) of newborns, all from the non-isolated ARSA group.

Conclusions: These findings emphasize the significance of distinguishing between isolated and non-isolated ARSA cases in prenatal diagnosis and clinical management, suggesting that isolated ARSA may be considered a normal vascular variation.