According to a recent hypothesis,
venous thrombosis results from the concurrence of several factors. This hypothesis was assessed in patients with portal or hepatic
venous thrombosis by simultaneously investigating most of the currently identified prothrombotic disorders, local precipitating factors, and other risk factors such as
oral contraceptive use. Patients with a tumorous obstruction and patients with
cirrhosis with portal vein
thrombosis were excluded. The prothrombotic disorders that were investigated included classical and occult
myeloproliferative disorders;
antiphospholipid syndrome;
protein C;
protein S and
antithrombin deficiency; factor V Leiden;
factor II; and
methylene-tetrahydrofolate-reductase gene mutations. We found 1 or several prothrombotic disorders and a local precipitating factor in 26 and 10 of the 36 patients with portal vein
thrombosis, respectively; and in 28 and none of the 32 patients with
hepatic vein thrombosis, respectively. We found a combination of prothrombotic disorders in 5 and 9 patients with portal and
hepatic vein thrombosis, respectively, whereas such a combination is expected in less than 1% of asymptomatic subjects. Of the 10 patients with a local precipitating factor, 8 had a prothrombotic disorder. Of the 13 patients who use
oral contraceptives, 10 had a prothrombotic disorder. We conclude that portal or hepatic
venous thrombosis should be regarded as an index for 1 or several prothrombotic disorders, whether or not local precipitating factors or
oral contraceptive use are found. Concurrence of prothrombotic disorders is more common than expected. Extensive investigation of prothrombotic disorders and anticoagulation should be considered in patients with portal or hepatic
venous thrombosis.