ASYMPTOMATIC MEMBRANOUS OBSTRUCTION OF THE INFERIOR VENA-CAVA FORMINGINTRAHEPATIC COLLATERAL PATHWAYS

Intrahepatic and/or extrahepatic collateral pathways result from the m embranous obstruction of the inferior vena cava. These collaterals are usually insufficient to prevent Budd-Chiari syndrome. We reprot an un usual case of asymptomatic membranous obstruction of the inferior vena cava in which marked intrahepatic collateral pathways were formed. Al though the inferior vena cava terminated above the orifice of the righ t hepatic vein, the middle and left hepatic veins were patent above th e membrane, without narrowing. Blood from the inferior vena cava drain ed into the right atrium via the intrahepatic collaterals between the right and middle hepatic veins without resistance.