These tests require two different densities of barium drinks and effervescent granules, taken with a small amount of water. The radiodense barium allows the examination of the function and the anatomical lining of the esophagus, stomach and proximal small intestine, also known as the duodenum.

A barium swallow study is a variant of the UGI in which the patient’s swallowing mechanism, pharynx, and esophagus are the focus of the study. A small bowel follow-through is a continuation of a UGI whereby the entire small bowel is examined.