Diagnosis of Portal Vein Thrombosis

Portal vein thrombosis is considered to develop from portal venous vascular wall disorder, abnormal portal venous flow, and abnormalities of the blood coagulation system as the thrombogenic origins. Portal vein thrombosis can easily occur in patients with hepatic cirrhosis due to three additional factors. The first factor is the hyperpermeability of the gastrointestinal mucous membrane. Cirrhosis creates an environment susceptible to bacterial translocation, and loads to the flow of lipopolysaccharide into a portal vein, resulting in sinusoid wall injury. The second factor is clot formation promoted by portal venous congestion (sluggish blood flow) due to portal hypertension. The third factor is a decrease of antithrombin-III synthesis in liver cirrhosis. Among the underlying diseases of 539 cases of portal vein thrombosis in Japan in 2014, there were 434 cases (80.5%) of portal hypertension, whose breakdown consisted of 406 cases (75.3%) of liver cirrhosis, 25 cases of idiopathic portal hypertension, 8 cases of extrahepatic obstruction, and 7 cases of others, while 105 cases (19.5%) were not associated with portal hypertension. Secondary portal vein thrombus accounted for 69 (12.8%) of the total, if it is defined as that developed within 30 days after an operation or interventional radiology.