The splenic vein is a large vessel located retroperitoneally in the upper part of the abdominal cavity. The main function of this blood vessel is to drain the venous blood from the spleen. In addition to the spleen, it drains parts of the stomach, pancreas and the hindgut.
The splenic vein merges with the superior mesenteric vein to form the hepatic portal vein, which drains blood from the abdominal portion of the gastrointestinal tract, as well as the gallbladder, spleen and pancreas, into the liver.
|Splenic lobar veins
|Short gastric veins, left gastroepiploic vein, pancreatic veins, inferior mesenteric vein
|Hepatic portal vein
|Spleen, body and tail of the pancreas, fundus and greater curvature of the stomach, hindgut (distal transverse colon, descending colon, sigmoid colon and rectum)
This article will discuss the anatomy and function of the splenic vein.
Anatomy and course
The splenic vein begins within the splenorenal ligament found in the left hypochondriac region of the abdomen. It is formed by the union of the lobar veins that emerge from the hilum of the spleen. From its origin site, the splenic vein runs horizontally toward the midline, below the accompanying splenic artery and deep to the tail and body of the pancreas.
As it courses over the upper posterior abdominal wall, the splenic vein passes anterior to the left kidney, renal hilum and left renal vessels. The vein crosses the midline at the level of the first lumbar vertebra, anterior to the abdominal aorta and the origin of the superior mesenteric artery. The splenic vein terminates posterior to the neck of the pancreas, where it unites with the superior mesenteric vein at the splenic-mesenteric confluence to form the hepatic portal vein.
Tributaries and drainage area
Along its course, the splenic vein receives several tributaries that drain the surrounding structures. These tributaries include:
- The short gastric veins, which drain the fundus of the stomach.
- The left gastroomental (gastroepiploic) vein, which drains the greater curvature of the stomach.
- The pancreatic veins, which drain the body and tail of the pancreas.
- The inferior mesenteric vein, which drains the hindgut.
Additionally, the splenic vein receives retroperitoneal veins and may occasionally receive the left gastric vein, which drains the fundus and upper body of the stomach.
To learn more about the veins and arteries of the small intestine, explore our articles, quizzes, video tutorials and labelled diagrams.
Splenic vein thrombosis
Thrombosis of the splenic vein causes obstruction of venous drainage, leading to increased pressure and reversal of the normal direction of blood flow through the splenic vein. This backflow of blood through the splenic vein can cause splenomegaly, a condition in which the spleen becomes engorged and enlarged. In order to shunt blood around the occluded splenic vein and maintain circulation, collateral pathways are employed in the form of portosystemic anastomoses and splenoportal collaterals. For example, the blood is shunted through the portosystemic anastomosis between the gastric veins (portal) and the esophageal veins (systemic). This often results in dilated submucosal veins within the stomach and lower esophagus called gastric and esophageal varices, respectively.
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