Prenatal Diagnosis of an Isolated Persistent Left Superior Vena Cava With Absent Right Superior Vena Cava: A Case Report.

Persistent left superior vena cava (PLSVC) with absent right superior vena cava (RSVC) is a rare congenital venous anomaly resulting from the failure of the left anterior cardinal vein to regress. Although often asymptomatic in isolated cases, prenatal diagnosis has clinical benefits, including the exclusion of coexisting congenital heart disease (CHD) and awareness of possible complications during central venous access or pacemaker implantation. We report the case of a 34-year-old G2P1 woman who underwent a fetal echocardiography at 34 weeks of gestation. Examination of the four-chamber view (4CV) revealed an enlarged coronary sinus adjacent to the left atrium, suggesting a PLSVC. Subsequent assessment of the right ventricular outflow tract (RVOT) and three-vessel view (3VV) confirmed the absence of the RSVC and presence of a persistent left superior vena cava (LSVC). Color and spectral Doppler imaging of the aortic arch and isthmus showed no narrowing, ruling out coarctation of the aorta. The pregnancy progressed uneventfully, and the patient had a spontaneous vaginal delivery at 38 weeks, resulting in a healthy newborn. Postnatal evaluations, including echocardiography, confirmed PLSVC draining into a dilated coronary sinus, with no additional cardiac anomalies identified. Although truly isolated, PLSVC typically does not require special delivery planning or postnatal intervention; prenatal recognition allows clinicians to ensure thorough fetal cardiac evaluation, offer appropriate counseling, and plan for potential challenges with right-sided central venous access in the future.