A blood vessel that drains blood from the large intestine that usually terminates when reaching the splenic vein, which goes on to form the portal vein with the superior mesenteric vein (SMV). Anatomical variations include the IMV draining into the confluence of the SMV and splenic vein and the IMV draining in the SMV. The IMV lies to the right of the similarly name artery, the inferior mesenteric artery, which originates from the abdominal aorta. [WP,unvetted].