A barium swallow (also called a contrast esophagram), is a series of x-rays of your esophagus. For the test, you will drink a barium-containing liquid, which coats the inside of the esophagus and makes its shape and contours appear on x-rays. As the liquid moves from the mouth down to the esophagus, the physician can assess any narrowing, enlargement or abnormalities. You will most likely be asked not to eat or drink for 8 to 10 hours before the test.