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The inferior mesenteric vein connects in the majority of people on the splenic vein, but in some people, it is known to connect on the portal vein or the superior mesenteric vein. Roughly, the portal venous system corresponds to areas supplied by the celiac trunk , the superior mesenteric artery , and the inferior mesenteric artery .
It is a major component of the hepatic portal system, one of three portal venous systems in the human body; the others being the hypophyseal and renal portal systems. The portal vein is usually formed by the confluence of the superior mesenteric , splenic veins , inferior mesenteric , left , right gastric veins and the pancreatic vein .
As a radical treatment for portal hypertension, surgical creation of a portacaval fistula produces an anastomosis between the hepatic portal vein and the inferior vena cava across the omental foramen (of Winslow). This spares the portal venous system from high pressure which can cause esophageal varices, caput medusae, and hemorrhoids.
In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale. The hepatic lobule is a building block of the liver tissue, consisting of a portal triad, hepatocytes arranged in linear cords between a capillary network, and a central vein.
An interventional radiologist typically performs TIPS, which involves placing a stent between the portal vein and hepatic veins to lower blood pressure in the portal circulation. Compared to portacaval shunting, TIPS is less invasive, safer, and is now the preferred option for patients with advanced liver failure or those at high surgical risk.
The hepatic duct lies in front and to the right, the hepatic artery to the left, and the portal vein behind and between the duct and artery. It also transmits nerves and lymphatics . Sympathetic nerves - these provide afferent pain impulses from the liver and gall bladder to the brain.
The human hepatic portal system delivers about three-fourths of the blood going to the liver.The final common pathway for transport of venous blood from spleen, pancreas, gallbladder and the abdominal portion of the gastrointestinal tract [2] (with the exception of the inferior part of the anal canal and sigmoid colon) is through the hepatic portal vein.
A dilated portal vein (diameter of greater than 13 or 15 mm) is a sign of portal hypertension, with a sensitivity estimated at 12.5% or 40%. [18] On Doppler ultrasonography , a slow velocity of <16 cm/s in addition to dilatation in the main portal vein are diagnostic of portal hypertension. [ 19 ]