Single left superior vena cava: antenatal diagnosis, associated anomalies and outcomes

OBJECTIVES: To describe the associated cardiac and extracardiac findings and estimate the prevalence of single left superior vena cava (LSVC) among fetuses referred for fetal echocardiography. METHODS: This was a retrospective case series of fetuses diagnosed with situs solitus and single LSVC at the Brompton Centre for Fetal Cardiology, London, UK, from October 2006 to December 2020. Prenatal and postnatal outcome data were collected. Prenatal diagnosis was based on abnormal vessel alignment at the three‐vessel view and/or three‐vessel‐and‐trachea view, showing a vessel to the left of the pulmonary artery (i.e. the LSVC) and absence of the usual vessel to the right of the ascending aorta (i.e. the right superior vena cava), and further visualization of the LSVC draining into the coronary sinus. RESULTS: Of 19 968 fetal echocardiograms performed during the study period, 34 cases of single LSVC were identified (a prevalence of 0.17%). Of these, 32 pregnancies had a live birth, one was lost to follow‐up and one resulted in intrauterine demise. Single LSVC was isolated in 79.4% of cases. No major congenital heart disease was identified. One fetus showed mild isthmus hypoplasia, with no aortic coarctation postnatally. Two fetuses had umbilical vessel abnormalities. A genetic abnormality was found in one case (15q24.1‐q24.2 deletion). CONCLUSIONS: Antenatal diagnosis of single LSVC in the setting of situs solitus is usually a benign isolated finding. Nevertheless, investigation of other cardiac, extracardiac and genetic disorders should be considered. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.