Extrahepatic portosystemic shunts are a rare venous abnormality that can be congenital or acquired.

Those of congenital origin are classified by the Abernethy Classification System, either type 1 or 2. This kind is associated with other issues such as an increase in liver tumors (FNH, HCC etc.)

Shunts that are acquired are the result of chronic portal venous hypertension that results in small portosystemic anastomoses to dilate. Lee et al mention that there are over 20 variations of acquired shunts described in the literature, with varices occurring in a number of areas including esophagus, gastric, paraumbilical, coronary and azygos veins.

It is important that venous anomalies like these are assessed and described as issues (some life-threatening) can be associated, including pyelothrombosis, or portal vein thrombus, pylephlebitis, gas within the venous system and venous calcifications.