Portal vein thrombosis is associated with malignancy, protein C and S deficiency, ulcerative colitis, Behcet's disease, cirrhosis, and secondary to instrumentation (e.g. umbilical venous catheterization in neonates). The diagnosis is usually made with ultrasound. Complete occlusion leads to portal hypertension and portal-systemic collateral channels. Treatment consists of anticoagulation. Infusion of plasminogen activators through a percutaneous transhepatic approach was shown to be effective in patients with active ulcerative colitis.