Commonest cause of Budd Chiary syndrome is:
Valve in the IVC
Hepatocellular carcinoma
Paroxysmal nocturnal hemoglobinuria
Renal cell carcinoma
Answer is C (Paroxysmal nocturnal hemoglobinuria): The most common cause of hepatic vein thrombosis from the list mentioned in Harrison is Paroxysmal nocturnal hemoglobinuria, and hence is the answer of choice here.