Interruption of the inferior vena cava with azygos termination associated with congenital absence of portal vein

The authors report an exceptional and well-documented case of interruption of the retrohepatic segment of the inferior vena cava with an "azygos conti nuation", combined with absence of the portal vein. The only known combinat ion of congenital anomalies of the inferior vena cava and the portal vein w as that of an "azygos continuation" and a preduodenal portal vein. The doub le interruption, portal and inferior caval, may be associated with a distur bance of preferential flows induced by the left umbilical thrust. According to hemodynamic theory, the left umbilical flow is the determining factor i n organogenesis of the portal vein and the retrohepatic segment of the infe rior vena cava.