Barium swallow

A barium swallow is a diagnostic procedure for the esophagus and the stomach in which a patient swallows barium sulphate, which blocks x-rays, and then is subjected to fluoroscopy.  The material coats the esophagus, allowing it to be seen as a hollow tube. It is usually used with sodium bicarbonate, which creates gas when swallowed, which doesn't block x-rays at all and shows as white areas.
The test involves exposure to a fair amount of radiation, and should be avoided in pregnant women and children.  As the barium sulphate will irritate tissues outside of the digestive tract, it should also be avoided if a tear is suspected.
Barium swallow at Wikipedia
Category:Medical procedures