Introduction
Portosystemic shunts (PSS) are a direct venous connection between the portal vein and the systemic circulation bypassing the liver parenchyma. Usually the venous return from the intestines, stomach, spleen, and pancreas flows into the portal vein and then through the sinusoidal network within the liver before draining into the hepatic veins and then into the caudal vena cava.
PSS can be congenital or acquired. In acquired shunting the abnormal venous connections form due to chronic portal hypertension. Primary portal vein hypoplasia is another variation without portal hypertension leading to microscopic malformation of the hepatic vasculature (Christiansen et al. 2000).Other conditions that can mimic clinical signs of liver failure include protein losing enteropathy and primary liver disease (cirrhosis and fibrosis). Microdntrahepatic portosystemic shunts can be a challenging diagnosis and needs to be differentiated from liver cirrhosis and fibrosis, which can only be made with histopathology.
When blood bypasses the liver, it leads to atrophy of the liver and eventually to liver failure. A loss of liver function leads to toxin build-up and loss of products normally produced by the liver (albumin, urea, glucose and clotting factors).