An EGD or "upper endoscopy" is done to investigate swallowing issues, heartburn, ulcers, abdominal pain, bleeding, digestive diseases, weight loss, and cancers. During an upper endoscopy a slim fibreoptic camera is inserted into the mouth, and advanced down through the esophagus, stomach, and into the beginning of the small bowel.

An ERCP is done to investigate and treat blockages and other abnormalities of the bile duct and pancreatic duct. ERCP is a specialized form of upper endoscopy that uses a slim fibreoptic camera, an x-ray machine, and contrast dye.

Lower endoscopy is done to investigate infections/inflammation/ischemia of the colon, abnormal bowel habits, abdominal pain, bleeding, weight loss, and cancers. It is also done as part of colon cancer screening and prevention. The goal of screening colonoscopy is to find and remove polyps, which are small growths that can turn into cancers over time if they are left untreated.

There are two types of lower endoscopy: colonoscopy and sigmoidoscopy.

During a colonoscopy a slim fibreoptic camera is inserted into the anus, and advanced backwards through the colon into the end of the small bowel.

During a sigmoidoscopy a shorter fibreoptic camera is used that can see much, but not all, of the colon.