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.
The other major venous channel in the area is the splenic vein (3), which lies deep and parallel to the splenic artery along the superior aspect of the pancreas. The splenic vein also receives venous drainage from the greater curvature of the stomach and the pancreas, as well as from the colon, through the inferior mesenteric vein (8). When a splenorenal shunt is performed, meticulous dissection of this vein from the pancreas with ligation of the numerous small vessels is necessary. As the dissection proceeds, the splenic vein comes into closer proximity with the left renal vein where anastomosis can be performed. The point of anastomosis is proximal to the entrance of the inferior mesenteric vein.
The venous configuration on the gastric wall is relatively constant. In performing a conservative hemigastrectomy, venous landmarks can be used to locate the proximal line of resection. On the lesser curvature of the stomach, the third branch (5a) of the coronary vein down from the esophagocardiac junction is used as a point for transection. On the greater curvature of the stomach the landmark is where the left gastroepiploic vein (9) most closely approximates the gastric wall (9a). Transection is carried out between these two landmarks (5a, 9a).
The anterior and posterior pancreaticoduodenal veins (10) produce an extensive venous network about the head of the pancreas. They empty into the superior mesenteric or hepatic portal vein. The anterior surface of the head of the pancreas is relatively free of vascular structures, and blunt dissection may be carried out here without difficulty. There is, however, a small anastomotic vein (11) between the right gastroepiploic (12) and the middle colic vein (13). This vein, if not recognized, can produce troublesome bleeding in the mobilization of the greater curvature of the stomach, as well as of the hepatic flexure of the colon. The pancreaticoduodenal veins have assumed new importance with the advent of transhepatic venous sampling and hormonal assays for localization of endocrine-secreting tumors of the pancreas and duodenum.
In executing the Kocher maneuver, no vessels are encountered unless the maneuver is carried inferiorly along the third portion of the duodenum. At this point the middle colic vessels (13) cross the superior aspect of the duodenum to enter the transverse mesocolon. Unless care is taken in doing an extensive Kocher maneuver, this vein may be injured.
The lymphatic drainage of the upper abdominal viscera is extensive. Lymph nodes are found along the course of all major venous structures. For convenience of reference, there are four major zones of lymph node aggregations. The superior gastric lymph nodes (A) are located about the celiac axis and receive the lymphatic channels from the lower esophageal segment and the major portion of the lesser curvature of the stomach, as well as from the pancreas. The suprapyloric lymph nodes (B) about the portal vein drain the remaining portion of the lesser curvature and the superior aspect of the pancreas. The inferior gastric subpyloric group (C), which is found anterior to the head of the pancreas, receives the lymph drainage from the greater curvature of the stomach, the head of the pancreas, and the duodenum. The last major group is the pancreaticolienal nodes (D), which are found at the hilus of the spleen and drain the tail of the pancreas, the fundus of the stomach, and the spleen. There are extensive communications among all these groups of lymph nodes. The major lymphatic depot, the cisterna chyli, is found in the retroperitoneal space. This communicates with the systemic venous system by way of the thoracic duct into the left subclavian vein. This gives the anatomic explanation for the involvement of Virchow's node in malignant diseases involving the upper abdominal viscera.