Risk factors and natural history. Since the first description of portal vein thrombosis (PVT) by Balfour and Stewart in 1869, in their report of a 20-year-old patient who died from complications of splenomegaly, ascites, and varicose dilation with associated PVT, the clinical manifestations and management of PVT have been met with great interest.1 PVT is classically defined as obstruction of ....