A flexible sigmoidoscopy (sig moi-DOS-kuh-pee) is an exam used to evaluate the lower part of the large intestine (colon). During a flexible sigmoidoscopy exam, a thin, flexible tube (sigmoidoscope) is inserted into the rectum.A tiny video camera at the tip of the tube allows the doctor to view the inside of the rectum and most of the sigmoid colon - about the last two feet (61 centimeters) of the large intestine. If necessary, tissue samples (biopsies) can be taken through the scope during a flexible sigmoidoscopy exam.Flexible sigmoidoscopy doesn't allow the doctor to see the entire colon. As a result, any cancers or polyps farther into the colon can't be detected with flexible sigmoidoscopy alone.