The left colic vein assists the body by draining old blood from the intestines.

The left colic vein is a branch of the inferior mesenteric vein that is responsible for draining the left flexure and descending colon. The left flexure is a sharp bend under the spleen where the transverse colon joins the descending colon. The descending colon is part of the large intestine. It lies on the left side and extends from the left flexure to the sigmoid colon.

The inferior mesenteric vein returns blood from the rectum, sigmoid colon and descending colon, emptying the blood into the splenic vein, which carries blood away from the spleen.