AGENESIS OF THE DUCTUS VENOSUS AND ITS CORRELATION TO HYDROPS-FETALISAND THE FETAL HEPATIC CIRCULATION - CASE-REPORTS AND REVIEW OF THE LITERATURE

Under normal conditions about 50% of the placental venous return bypas ses the liver through the ductus venosus. This blood flow is preferent ially directed toward the foramen ovale and provides optimum oxygenati on to the fetal heart and brain. Absence of the ductus venosus is a ra re vascular anomaly, the significance of which has been disputed. We d istinguish the pattern in which the liver is entirely bypassed, a mani festation of a fundamental malformation in the umbilical venous system , from the pattern in which the ductus venosus is absent despite a nor mal course of the umbilical vein. We review the literature regarding t he latter and report eight new cases. Three of the four previously rep orted cases showed associated malformations and two of them suffered f rom portal congestion and hydrops. Among our eight cases three showed severe malformations in the cardiovascular system. Three cases present ed themselves with hydrops fetalis and disturbance in the portal circu lation, and two cases expressed signs of intrauterine asphyxia. The ab sence of the ductus venosus might be a minor vascular maldevelopment r esulting in an early disturbance in the portal circulation. Our findin gs suggest that this anomaly might induce hydrops fetalis.