Prenatal Ultrasound Diagnosis of a Rare Vascular Ring Formed by Left Aortic Arch and Right Ductus Arteriosus: A Case Report

BACKGROUND: To guide prenatal recognition and management of this rare vascular ring formed by the left aortic arch and right ductus arteriosus. METHODS: A 23-week primigravida with an abnormal three-vessel tracheal (3VT) view underwent fetal ultrasound, chromosomal copy number variation (CNV) sequencing, and subsequent pregnancy termination. RESULTS: Ultrasound revealed a vascular ring formed by left aortic arch and right ductus arteriosus that encircled and compressed the trachea and esophagus, accompanied by thymic hypoplasia, enlarged posterior fossa, and single umbilical artery; CNV confirmed 22q11.2 deletion syndrome. Postmortem examination verified the structural abnormalities identified on prenatal ultrasound. CONCLUSION: This first reported case of a rare vascular ring with a left aortic arch and a right ductus arteriosus confirmed by postmortem examination validates the diagnostic efficacy and accuracy of prenatal ultrasound, with the 3VT view serving as the key diagnostic plane, and highlights the need for genetic assessment in perinatal management.