Endoscopy is a nonsurgical procedure used to examine a person’s digestive tract. Using an endoscope, a flexible tube with a light and camera attached to it, your doctor can view pictures of your digestive tract on a color TV monitor.
During an upper endoscopy, an endoscope is easily passed through the mouth and throat and into the esophagus, allowing the doctor to view the esophagus, stomach, and upper part of the small intestine.
Similarly, endoscopes can be passed into the large intestine (colon) through the rectum to examine this area of the intestine. This procedure is called sigmoidoscopy or colonoscopy depending on how far up the colon is examined.