The type of obstruction in Budd-Chiari syndrome is

Budd Chiari Syndrome BCS is caused by obstruction of hepatic venous outflow producing intense congestion of liver Etiology Polycythemia Vera is the MC etiology In the West, thrombosis of the major hepatic veins is more common In BCS all three major hepatic veins usually are occluded Small hepatic veins that join the retro hepatic IVC, paicularly veins draining the caudate lobe are spared Membranous obstruction of IVC is MC cause of BCS in Japan, China, India and South America Infections causing BCS : Filariasis, amebic liver abscess, aspergillosis, schistosomiasis, syphillitic gumma & hydatid disease MC cancers associated with BCS : HCC, RCC, adrenal carcinoma & Leiomyosarcomas oglf the IVC Ref: schwaz's principle of surgery 10th edition Pgno : 1283-1284