Identification and management of fetal isolated right-sided aortic arch in an unselected population

Objective: Inclusion of the three vessels and trachea view in the routine assessment of the fetal heart at the 18-20-week morphology scan improves recognition of a right-sided aortic arch (RAA). We report our experience of RAA diagnosed in an unselected population of pregnant women attending for a routine morphology scan. Methods: The obstetric imaging databases of two ultrasound centers were reviewed retrospectively to identify all routine fetal morphology scans performed at 18-22 weeks' gestation between January 2011 and December 2014. A review of postnatal charts was conducted to ascertain findings at birth, neonatal complications and the anatomical findings at any neonatal echocardiographic or surgical procedure. Parents of older infants were contacted by phone to assess their wellbeing and identify any respiratory or feeding difficulties. Results: In the 48-month study period, 43 083 routine anomaly scans were performed. Twenty-three cases of isolated RAA were identified, a prevalence of 0.05%. Nineteen (83%) cases of isolated RAA had a left-sided arterial duct and four (17%) had a right-sided duct. Postnatal follow-up data were obtained in all cases. The prevalence of a symptomatic vascular ring due to a double aortic arch was 13% (3/23). One (4%) case was diagnosed with DiGeorge syndrome. Conclusions: RAA can be identified easily on a routine fetal anomaly scan, however the prevalence of RAA is low in an unselected population. Antenatally diagnosed cases should be referred for detailed fetal echocardiography and the patient should be made aware of the association with DiGeorge syndrome and the symptoms associated with a vascular ring.