Macroscopic intrahepatic portosystemic venous shunt: review of the literature and reclassification

Macroscopic intrahepatic portosystemic venous shunts (IHPSS) are defined as communications between the portal and the systemic venous circulation, mea suring more than 1mm in diameter, and at least partially located inside the liver. Four different types can be identified based on anatomical, clinica l, and pathophysiological criteria. Type I includes patent paraumbilical ve ins, located in the liver, and commonly encountered in portal hypertension. Types II, III, and IV are much less common and have been reported in only 47 publications in the entire French and English literature. They include s hunts, unique or multiple, between a portal branch and a hepatic vein, loca ted either in two adjacent liver segments (type II) or in non-adjacent live r segments (type III). Type IV corresponds to any tubular communication dev eloped between the right portal branch and the inferior vena cava. The exceptional patent ductus venosus or a patent umbilical vein should not be considered as IHPSS since their course is strictly extrahepatic.