Inferior vena caval obstruction: transvenous instrumental membranotomy.

Five transvenous instrumental membranotomies were performed in four patients with membranous obstruction of the hepatic segment of the inferior vena cava. Membranotomy was done with a specially designed instrument similar to a Tubbs' dilator, which was inserted through femoral or the right internal jugular veins. Pressure gradients across the membrane disappeared after membranotomy and the release of the stenosis was confirmed by angiography and ultrasonography. One patient needed a second membranotomy because of recurrent stenosis 7 years after the initial procedure.