Abnormal portal venous system morphology Thickened intrahepatic portal venules 2023-02-20T13:53:34Z Increased width of the vascular wall of portal venules within the liver. The portal vein (PV) is the main vessel of the portal venous system (PVS), which drains the blood from the gastrointestinal tract, gallbladder, pancreas, and spleen to the liver. Once in the liver, the PV ramifies and reaches the sinusoids, forming portal venules.