Endoscopy is a visual examination of the gastrointestinal tract using a lighted, flexible fiberoptic or video endoscope. In gastroenterology, this procedure is called either gastroscopy, the examination of the upper gastrointestinal tract; sigmoidoscopy, the visual examination of the rectum and sigmoid colon; or colonoscopy, which is the examination of the entire lower gastrointestinal tract.
The flexible endoscope is a remarkable piece of equipment that can be gently directed and moved around the bends and turns of the gastrointestinal tract. Endoscopes now come in two types. The original pure fiberoptic instrument has a flexible bundle of glass fibers that collect the lighted image at one end and transfer the image to the eye piece. The newer video endoscopes have a tiny, color TV camera with a wide-angle lens at the end. Electronic signals are then transmitted up the scope to the computer which then displays the image on a large video screen. An open channel in these scopes allows other instruments to be passed through in order to take tissue samples, remove polyps, and perform other exams.