Agenesis of the ductus venosus and its correlation to hydrops fetalis

Absence of the ductus venosus is a rare vascular anomaly. We report a late onset of a hydrops fetalis seen in a fetus at 34 completed weeks of gestation. A persistence of the cranial parts of the left and right umbilical veins and of the paired cranial vitelline veins with an absent ductus venosus led to a bilateral hydrothorax, ascites and skin-edema. Postnatally the hydrops resolved within 7 days most probably due to the change from the fetal to the adult circulation. The abnormal venous system was confirmed by angiography. Agenesis of the ductus venosus can manifest in two different morphologic patterns: The umbilical vein drains exclusively into the left branch of the intrahepatic portal vein or the umbilical vein drains into the inferior vena cava or directly into the right atrium by-passing the liver completely. In both patterns, the preferential direction of the flow towards the foramen ovale is not present. While the first pattern leads to hyperperfusion of the liver parenchyma, the latter would result in reduced perfusion and oxygenation. Our findings suggest that agenesis of ductus venosus might induce hydrops fetalis. We conclude, that in every case of hydrops fetalis the venous system should be evaluated by ultrasonography prenatally and/or immediately postnatally.