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Portal hypertension is hypertension (high blood pressure) in the portal vein system, which is composed of the portal vein, and its branches and tributaries. Portal hypertension is defined as elevation of hepatic venous pressure gradient to >5mmHg. Generally, in clinical practice the pressure is not measured directly until the decision to place a transjugular intrahepatic portosystemic shunt (TIPS) has already been made. As part of that procedure, a hepatic vein wedge pressure is measured with the assumption of no pressure drop across the liver yielding portal vein pressure. ==Signs and symptoms== Consequences of portal hypertension are caused by blood being forced down alternate channels by the increased resistance to flow through the systemic venous system rather than the portal system. They include: * Ascites (free fluid in the peritoneal cavity). * Hepatic encephalopathy. * Increased risk of spontaneous bacterial peritonitis. * Increased risk of hepatorenal syndrome. * Splenomegaly (enlargement of the spleen) with a consequent accumulation of red blood cells, white blood cells, and platelets, together leading to mild pancytopenia. * Development of varices at portacaval anastomoses: Esophageal varices, gastric varices, anorectal varices (not to be confused with hemorrhoids), and caput medusae. Esophageal and gastric varices pose an ongoing risk of life-threatening bleeding, with bloody vomiting or melena. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「portal hypertension」の詳細全文を読む スポンサード リンク
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