Changing perspectives in portal vein thrombosis

The aetiology of portal vein thrombosis (PVT) is heterogeneous. Important primary risk factors for PVT are cirrhosis, hepatobiliary malignancies and pancreatitis. Newly discovered thrombotic risk factors, such as latent myeloproliferative disorders and prothrombotic genetic defects, have also been identified as major risk factors for PVT. At least one-third of PVT patients demonstrate a combination of thrombotic risk factors. PVT, which does not have a detrimental effect on liver function, usually becomes manifest as a variceal haemorrhage in the oesophagus months to years after the development of thrombosis. Owing to intact coagulation variceal bleeding has a better prognosis among patients with PVT than cirrhotics. Endoscopic sclerotherapy or band ligation is the primary therapeutic option for variceal bleeding in patients with PVT. It is questionable whether anticoagulant therapy should be started, since it has not proven beneficial for most PVT patients. Therapy with anticoagulants is only recommended for those with acute PVT (especially in association with mesenteric vein thrombosis), those who recently underwent a portosystemic shunt procedure, and those with other thrombotic manifestations, particularly in case of proven hypercoagulability. Mortality of patients with PVT may be associated with concomitant medical conditions which lead to the PVT or with manifestations of portal hypertension, such as variceal haemorrhage. Multivariate analysis of a large Dutch PVT population has shown that age, malignancy, ascites and the presence of mesenteric vein thrombosis are independently related to survival. Death due to a variceal haemorrhage is rare. Poor outcome of PVT thus appears to be associated primarily with concomitant diseases which lead to PVT, and not the complications of portal hypertension. It is therefore uncertain whether surgical portosystemic shunting affects survival favourably.