Upper endoscopy allows your gastroenterologist to examine the lining of the upper part of your gastrointestinal tract, which includes the esophagus, stomach and duodenum (first portion of the small intestine). Your gastroenterologist will use a thin, flexible tube called an endoscope, which has its own lens and light source, and will view the images on a video monitor. Upper endoscopy is also referred to as as upper GI endoscopy, esophagogastroduodenoscopy (EGD) or panendoscopy.

Links
For more information please see here