Medical Content Created by the Faculty of the
Harvard Medical School
A barium swallow, or upper GI series, is an x-ray test used to examine the upper digestive tract (the esophagus, stomach, and small intestine). Because these organs are normally not visible on x-rays, you need to swallow barium, a liquid that does show up on x-rays. The barium temporarily coats the lining of the esophagus, stomach, and intestine, making the outline of these organs visible on the x-ray pictures. This test is useful for diagnosing cancers, ulcers, problems that cause narrowing of the esophagus, some causes of inflammation in the intestine, and some swallowing problems.