Ileus occurs when there is a problem with motility in the stomach and small or large intestine (bowel). Motility is the movement of food and waste through the digestive tract. Ileus is not caused by a physical blockage (obstruction).
Normally, muscles in the bowel walls squeeze (contract) to move waste along. Signals from nerves tell the muscles when to contract. With ileus, this movement slows down or stops completely. As a result, waste can't move through the bowels and out of the body. This can cause belly (abdominal) pain and other symptoms. Treatment is needed to restore normal movement and ease symptoms.