PRENATAL DIAGNOSIS Prenat Diagn 2011; 31: 380–388. Published online 20 January 2011 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pd.2699 Prenatal diagnosis of abnormal cardinal systemic venous return without other heart defects: a case series Catherine Barrea 1,2 *, Caroline Ovaert 1 , St´ ephane Moniotte 1 , Jean-Marc Biard 2 , Patricia Steenhaut 2 and Pierre Bernard 2 1 Pediatric Cardiology Unit, Department of Pediatrics, Cliniques universitaires Saint Luc, UCL, Brussels, Belgium 2 Fetal Medicine Unit, Department of Obstetrics and Gynecology, Cliniques universitaires Saint Luc, UCL, Brussels, Belgium Objectives To describe fetal spectrum and echocardiographic characteristics of anomalous systemic venous return (ASVR, cardinal veins) without other structural heart defects (isolated ASVR), evaluate associated extracardiac and genetic anomalies and review neonatal outcome. Methods From 2003 to 2009, 369 consecutive fetuses were diagnosed with cardiac malformation, including 27 cases with an isolated ASVR. The following variables were collected: type of ASVR, extracardiac anomalies, karyotype and short-term outcome. Results The most common forms of ASVR were persistent left superior vena cava (SVC) (n = 15) and interrupted inferior vena cava (IVC) (n = 6). The other ASVR types were a persistent left SVC without a right SVC (n = 4), bilateral agenesis of the SVC with cephalic venous drainage toward the IVC through the azygos system (n = 1) and total ASVR to the coronary sinus (n = 1). Genetic disorders were confirmed in five cases, all with a persistent left SVC, with extracardiac anomalies present in four of them. Ten other patients had extracardiac anomalies detected prenatally or postnatally. When available, ASVR diagnosis was confirmed postnatally in all cases. Conclusion Isolated ASVRs can be accurately diagnosed prenatally and are frequently associated with extracardiac and genetic anomalies. A detailed morphological ultrasound and fetal karyotype should be suggested. Neonatal outcome was mainly related to the associated anomalies. Copyright  2011 John Wiley & Sons, Ltd. KEY WORDS: congenital heart defects; systemic venous return; cardinal veins; fetal echocardiography; diagnosis; outcome INTRODUCTION Increasing experience in fetal ultrasound (US) and fetal echocardiography leads to more frequent diagnoses of anatomically subtle congenital heart defects (CHD) (Hornberger and Barrea, 2001) such as anomalous systemic venous return (ASVR) of the cardinal veins not associated with other structural heart defects (isolated ASVR). Congenital anomalies of the cardinal systemic venous drainage to the heart represent a heterogeneous group of malformations with variable consequences (Freedom et al., 1997; Fasouliotis et al., 2002). Prenatal diagnosis of ASVR has only been reported recently, mainly as case reports on the persistence of a left superior vena cava (SVC) or as series on persistent left SVC associated with other structural heart defects (Jouannic et al., 2003; Kalache et al., 2003; Pasquini et al., 2005a, 2006; Berg et al., 2006; Guarnieri et al., 2006; Galindo et al., 2007; Freund et al., 2008). The available literature on the echocardiographic features of an isolated ASVR, the associated extracardiac and genetic anomalies and the perinatal outcome is scarce. *Correspondence to: Catherine Barrea, Pediatric Cardiology Unit, Cliniques universitaires Saint Luc, 10 Avenue Hippocrate, 1200 Brussels, Belgium. E-mail: catherine.barrea@uclouvain.be Such information is however crucial to guide both prenatal parental counseling and perinatal management. Our objectives were (1) to describe the prenatal spec- trum and echocardiographic characteristics of ASVR of the cardinal veins without other structural heart defects, (2) to evaluate the associated extracardiac and genetic anomalies and (3) to review neonatal outcome. METHODS Isolated ASVR was defined by the presence of an abnor- mal systemic venous connection (of the cardinal veins) to the heart not associated with another CHD. Anoma- lies of the umbilical and portal veins were not included. Small muscular ventricular septal defects or hyper- echogenic mitral valve spots were not considered as associated CHD. Cases of ASVR and cardiac asymme- try were not excluded as asymmetry may be related, to a certain degree, to ASVR. Drainage of a persistent left SVC into a dilated coronary sinus (CS) may indeed impair left inflow with subsequent diminutive left-sided heart structures (Jouannic et al., 2003; Pasquini et al., 2005a; Stos et al., 2007). From January 2003 to June 2009, 369 consecutive fetuses with a structural heart defect were retrieved from Copyright  2011 John Wiley & Sons, Ltd. Received: 7 October 2010 Accepted: 9 December 2010 Published online: 20 January 2011