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.