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The role played by coagulation defects in the occurrence of bleeding in cirrhosis is still unclear. This is partly due to the lack of tests that truly reflect the balance of procoagulant and anticoagulant factors in vivo. Conventional coagulation tests such as prothrombin time and activated partial thromboplastin time are inadequate to explore the physiological mechanism regulating thrombin, because they do not allow full activation of the main anticoagulant factor, protein C, whose levels are considerably reduced in cirrhosis. We used a thrombin generation test to investigate the coagulation function in patients with cirrhosis. Thrombin generation measured without thrombomodulin was impaired, which is consistent with the reduced levels of procoagulant factors typically found in cirrhosis. However, when the test was modified by adding thrombomodulin (i.e., the protein C activator operating in vivo), patients generated as much thrombin as controls. Hence, the reduction of procoagulant factors in patients with cirrhosis is compensated by the reduction of anticoagulant factors, thus leaving the coagulation balance unaltered. These findings help clarify the pathophysiology of hemostasis in cirrhosis, suggesting that bleeding is mainly due to the presence of hemodynamic alterations and that conventional coagulation tests are unlikely to reflect the coagulation status of these patients. In conclusion, generation of thrombin is normal in cirrhosis.

Current recommendations for early anticoagulation in acute portal vein thrombosis unrelated to cirrhosis or malignancy are based on limited evidence. The aim of this study was to prospectively assess the risk factors, outcome, and prognosis in patients managed according to these recommendations. We enrolled 102 patients with acute thrombosis of the portal vein, or its left or right branch. Laboratory investigations for prothrombotic factors were centralized. Thrombus extension and recanalization were assessed by expert radiologists. A local risk factor was identified in 21% of patients, and one or several general prothrombotic conditions in 52%. Anticoagulation was given to 95 patients. After a median of 234 days, the portal vein and its left or right branch were patent in 39% of anticoagulated patients (versus 13% initially), the splenic vein in 80% (versus 57% initially), and the superior mesenteric vein in 73% (versus 42% initially). Failure to recanalize the portal vein was independently related to the presence of ascites (hazard ratio 3.8, 95% confidence interval 1.3-11.1) and an occluded splenic vein (hazard ratio 3.5, 95% confidence interval 1.4-8.9). Gastrointestinal bleeding and intestinal infarction occurred in nine and two patients, respectively. Two patients died from causes unrelated to thrombosis or anticoagulation therapy. Conclusion: Recanalization occurs in one-third of patients receiving early anticoagulation for acute portal vein thrombosis, whereas thrombus extension, intestinal infarction, severe bleeding, and death are rare. Alternative therapy should be considered when ascites and splenic vein obstruction are present. (HEPATOLOGY 2010;51:210-218.) A cute portal vein thrombosis (PVT) is characterized by the recent development of a thrombus in the portal vein or its left or right branches. 1,2 Extension to mesenteric venous arches causes intestinal infarction, with a reported mortality of up to 50%. 3,4 Without recanalization, a cavernoma develops, associated with a permanent risk of potentially fatal gastrointestinal bleeding, recurrent thrombosis, or biliary obstruction. 1,5,7 Recanalization is therefore a major goal for the treatment of acute PVT and is often a pressing challenge, because most PVT cases are recognized at the acute stage. 8 Expert panels have recommended early anticoagulation therapy for acute PVT. 2 However, these recommendations are based on small retrospective cohort studies performed over several decades. [9][10][11] The aim of this study was to prospectively assess (1) patient characteristics of those presenting with acute PVT unrelated to cirrhosis or malignancy; (2) the incidence and predictive factors of recanalization in patients managed according to recent recommendations; and (3) the incidence of disease-and treatment-related complications.

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