A portacaval anastomosis (also known as porto-systemic anastomosis or portal caval system) is a specific type of anastomosis that occurs between the veins of portal circulation and those of systemic circulation. The inferior end of esophagus and the inferior part of the rectum are some of the most important sites of portal systemic anastomosis.
It can be one of the conditions caused by portal hypertension. A useful mnemonic is that portal hypertension causes problems in the butt, the gut, and caput. A dilated inferior mesenteric vein may or may not be related to portal hypertension.