A barium meal, also known as an upper gastrointestinal series is a procedure in which radiographs of the esophagus, stomach and duodenum are taken after barium sulfate is ingested by a patient. Barium meals are useful in the diagnosis of structural and motility abnormalities of the foregut. The gastrointestinal tract, like other soft-tissue structures, does not show clearly enough for diagnostic purposes on plain radiographs. Barium salts are radioopaque: they show clearly on a radiograph. If barium is swallowed before radiographs are taken, the barium within the esophagus, stomach or duodenum shows the shape of the lumina of these organs...