A GI (gastrointestinal) endoscope is a medical device consisting of a flexible tube with a video camera in the tip.  Illumination is provided by glass fiber (fiberoptic) bundles in the tube  that transmit light from an external light source.  A hollow channel through the shaft allows insertion of small instruments that can be used to take samples of tissue.  Water can be injected through this channel for irrigation and, with suction, fluid can be withdrawn through this channel.  The physician controls the direction of the flexible tip with four-way controls.  Air can be pumped under low pressure through the endoscope to inflate the stomach or intestine.

These instruments are specially designed for visual inspection of the interior lining (mucosa) of the digestive tract.  There are several types of GI endoscopes, each designed specifically for examination of a particular area of the digestive tract.  The instruments come in different sizes, and the physician will select the instrument best suited for a particular patient’s examination.

The upper GI endoscope is designed for examination of the esophagus (food tube), stomach and duodenum (the first section of the small intestine), and it is passed through the mouth.  The standard upper endoscope is one meter (39 inches) in length and 9.5 mm (3/8 inch) in diameter.  Colonoscopes are designed for examination of the large intestine (rectum, colon and cecum), and the colonoscope is passed through the anus.  Colonoscopes are longer (1.7 meter or about 5.6 feet) and somewhat larger in diameter than the upper GI endoscope.