The venous blood supply of the upper abdomen parallels the arterial blood supply. The portal vein (1) is the major vessel that has the unique function of receiving venous blood from all intraperitoneal viscera with the exception of the liver. It is formed behind the head of the pancreas by the union of the superior mesenteric (2) and splenic (3) veins. It ascends posterior to the gastrohepatic ligament to enter the liver at the porta hepatis. It lies in a plane posterior to and between the hepatic artery on the left and the common bile duct on the right. This vein has surgical significance in cases of portal hypertension. When portacaval anastomosis is performed, exposure is obtained by means of an extensive Kocher maneuver. Several small veins (4) from the posterior aspect of the pancreas enter the sides of the superior mesenteric vein near the point of origin of the portal vein. Care must be taken to avoid tearing these structures during the mobilization of the vein. Once hemorrhage occurs, it is difficult to control.

The coronary (left gastric) vein (5) returns blood from the lower esophageal segment and the lesser curvature of the stomach. It runs parallel to the left gastric artery and then courses retroperitoneally downward and medially to enter the portal vein behind the pancreas. It anastomoses freely with the right gastric vein (6), and both vessels drain into the portal vein to produce a complete venous circle. It has a significance in portal hypertension in that the branches of the coronary vein, along with the short gastric veins (7), produce the varicosities in the fundus of the stomach and lower esophagus.