50-year-old man who a week earlier had a transjugular intrahepatic portosystemic shunt (TIPS) installed. Currently admitted due to altered mental status. The TIPS seems to be patent. The liver looks normal in size with a smooth margin. A small fluid gap is seen subcapsularly just below the diaphragm.
The portal vein, a gateway between two capillary beds, is formed by the union of veins from the gastrointestinal tract, spleen and pancreas. Disorders of drainage to, from, or in the liver may lead to portal vein hypertension which may result in varice formation, ascites, splenomegaly, and all of its complications. The most common cause of portal vein hypertension is liver cirrhosis and scartissueformation which result in partial blockage of blood flow passing through the liver. When the portal vein pressure goes up, compensatory shunts are formed from the capillaries connecting the hepatic veins, bypassing the liver first pass metabolism. Elevated systemic nitrogen levels ensue. Hepatic encephalopathy in this setting can occur due to increased nitrogen levels, electrolyte and acid-base disorders, infections, drugs-induced or due to worsening liver failure.
TIPS, a bridge between the portal vein and the hepatic veins, is an alternative therapy refractory portal vein hypertension, ascites and variceal bleeding. However, this increases the immediate postoperative risk of hepatic encephalopathy.