Ileus is a lack of bowel function that can cause colic, vomiting, and/or constipation. Research has shown that bowel function slows down and possibly stops working for a short period of time after surgery, usually for 5-7 days. Patients report pain and discomfort from the gas that builds up in their bowel until the time the bowel begins working properly after surgery. During the period the bowel is not working after surgery, patients cannot leave the hospital until their physician is sure that their bowel function has returned. The return in bowel function is usually signaled by the passage of gas from the rectum.