Gastrointestinal series utilize x-rays to examine the structures of the gastrointestinal tract mainly esophagus, stomach and duodenum. Fluoroscopy is often used in the is type of imaging. This imaging technique generally use barium, which is a contrast agent with a white chalky appearance. Upon swallowing, the barium drink coats the inside walls of the gastrointestinal tract structures so that various characteristics of the esophagus, stomach, and duodenum can be visualized. A gastrointestinal series can help detect tumors, ulcers, hernias, diverticula, strictures, inflammation, and swallowing difficulties.