"Endoscopy (Upper Endoscopy)"

An endoscopy is a diagnostic test in which a small camera mounted on a tube is inserted into the digestive tract via the mouth or anus. In an upper endoscopy, which is used to diagnose some food intolerances, the camera allows gastroenterologists to observe the condition of the stomach, esophagus, and duodenum (the uppermost part of the small intestine).

Endoscopies are also used to observe the condition of other parts of the digestive tract and to diagnose conditions unrelated to food allergies or food intolerances.

Gastroenterologists can biopsy the inner lining of the small intestine to test for celiac disease during an endoscopy.