Arteriovenous fistulas of the placenta in a singleton fetus with large atrial septal defect and anomalous connection of the umbilical veins.

Arteriovenous fistulas of the placenta rarely occur in singleton pregnancies. This report describes the fetal and neonatal hemodynamic pattern in a singleton gestation in which multiple placental artery-to-vein anastomoses were associated with a large atrial septal defect and a single umbilical artery with an anomalous connection of the persistent right and left umbilical veins. Possible links between the extracardiac vascular malformation and the congenital heart defect are discussed.