Coagulation abnormalities in cirrhotic patients with portal vein thrombosis.

The liver has a central role in the clotting process and an altered haemostasis is common in advanced liver disease. Nevertheless, recent studies have questioned the historical belief that impaired haemostasis in liver disease means an increased risk of bleeding. Coagulation and anticoagulation mechanisms are still balanced but are set at a lower level. Platelet function and number also play a role. The prevalence of thrombotic events is similar in both cirrhotic patients and in the general population but the cirrhotic patients have an increased risk for thrombosis in the splanchnic area. Portal blood flow stasis is the main underlying change favouring thrombosis even if other local, systemic, congenital and acquired factors are present. The onset of portal vein thrombosis strongly affects the prognosis of liver cirrhosis, worsening both portal hypertension and liver function. Some of the known risk factors for venous thrombosis--G20210A mutation of prothrombin, factor V Leiden, endoscopic treatment of esophageal varices and abdominal surgery--have a specific role in the development of splanchnic thrombosis in cirrhotic patients. The knowledge of the pathophysiological aspects of portal vein thrombosis and clotting alterations in liver disease will allow determination of the indication, duration and timing of anticoagulation therapy.