A sigmoidoscopy is a test that allows the doctor to look directly at the lining of the lower end of the large intestine (rectum and sigmoid colon) using a flexible tube that has a light and video chip at the end (either a sigmoidoscope or a colonoscope). Prior to this test the child must take medications that will clean stool out of the colon. The scope is passed through the anus, into the rectum and then into the sigmoid colon. Frequently, tiny samples of cells (biopsies) are taken to look for inflammation, infection, or other problems.