A mechanical bowel obstruction can develop in either the small intestine or the large intestine (also called the colon). The condition partially or completely prevents the contents of the intestine and blood from flowing normally through the bowels.

The picture on the left shows a blockage in the small intestine that might develop, for example, as a result of scar tissue formation (adhesions). The picture on the right shows a partial blockage in the colon caused by a tumor (cancer).