Barium swallow is an X-ray examination of the upper gastrointestinal tract. It involves swallowing a solution containing barium sulfate, a metallic compound which is easily visualized on X-ray images. Barium coats the walls of the pharynx and esophagus and appears white on the images. It can be tracked as it moves through the digestive system by performing a series of X-rays. A barium swallow can help identify problems with swallowing and diagnose abnormalities of the esophagus and stomach.