Endoscopy is a test that uses a thin, flexible, lighted viewing instrument (endoscope) to allow a doctor to examine the inside of organs, canals, and cavities in the body.

Endoscopy can reveal problems that do not show up on X-ray tests and can sometimes eliminate the need for exploratory surgery. Tissue samples also may be collected and abnormal growths removed during endoscopy.

Different types of endoscopes can be used to study the sinuses, the upper digestive tract, the colon, the uterus, and other parts of the body.

For example, in an upper gastrointestinal endoscopy, the doctor guides the endoscope down the person's throat to examine the esophagus, stomach, and the upper part of the small intestine.