ABSTRACT
Objective To study the anatomical location and pathology of membranous obstruction of the inferior vena cava(IVC)in Budd-Chiari syndrome(BCS)with research on the etiologic mechanism and pathology.Methods Analysis of 100 normal adults was performed including the gross anatomy of IVC segment from the level of diaphragm up to right atrium.The conventional,microscopic pathologic examination of the biopsy sampling IVC obstruetice mambrane tissue in 70 cases toghther with the complete resected membrane from the radical therapy for 20 cases of BCS,were collected and under investigation.Results The macroscopic examination revealed the obstructive membrane in one case(1%)localizing at the diaphragmatic level,approximately 28 mm,away from the IVC entrance into the right atrium and a newly found valvula was seen on the left lateral wall of the upper part of the hepatic vein orifice.Simultaneously,47% adults showed Eustachiun valve existing in IVC near the entrance to right atrium.Microscopy confirmed all the forementioned membranes consisting of vascular valvular structures.Among them(21/70),30% showed additional organized thrombus formations,and 9%(6/70)with a few amount of inflammatory cellular infiltrations.The total intact resection membrane was continuous with the vascular wall under microscopic examination.Conclusions The first newly report of the existence of a special valvula at the diaphragmatic level of IVC reveals the possibility of high correlation with the occurance of IVC membranous obstruction type in BCS.