EP09.59: Fetal aberrant right subclavian artery: insights into association with additional soft markers, structural and chromosomal anomalies

The aim of our study is to follow up all fetuses with Fetal aberrant right subclavian artery (ARSA) detected between 16- 24 weeks of pregnancy for presence or absence of additional soft markers, structural and/or chromosomal anomalies and postnatal outcomes. This is a retrospective study of antenatally diagnosed ARSA from a tertiary fetal care centre in South India from 2008 to 2023. Fetuses with ARSA diagnosed in second trimester were analysed for presence or absence of additional soft markers, structural and/or chromosomal anomalies and postnatal wellbeing. 559 fetuses scanned by FMF certified operators, stored in Astraia software and outcomes collected by telephonic interview with parents confirming absence of neurodevelopmental delay, hospital records and prenatal testing if performed, were considered for further analyses. 559 fetuses were studied in 3 groups: 94/559(16.8%) had additional soft markers, 96/559(17.2%) had associated anomalies and 369/559(66%) had no other anomalies/markers. ARSA+ additional soft markers: Commonest were EIF, nuchal edema and hypoplastic nasal bone.7/80(8.8%) had abnormal KT. ARSA+ associated anomalies were subdivided into cardiac 46/96(47.9%) and extracardiac 50/96(52.1%). ARSA+ associated cardiac anomalies: Commonest were Right Aortic Arch, Tetralogy of Fallot and Atrioventricular Septal Defect. 3/18(16.7%) had abnormal Karyotype(KT). ARSA+ associated extracardiac anomalies: Most commonly involved flat facial profile. 8/18(44.4%) had abnormal KT. In isolated ARSA group, 6/351(1.7%) had abnormal KT. Except for one baby in additional soft marker group with ARSA, remaining 445 live births had no neurodevelopmental issues. ARSA is an important soft marker for chromosomal anomalies that can be easily identified on the prenatal scan. When detected, it is vital to assess for additional markers and structural anomalies as when associated the probability of a chromosomal or a genetic anomaly increases significantly. Once this has been excluded, the prognosis for these babies after birth appears to be excellent in our study.