A study used to detect and record the contractions of the muscles of the stomach and duodenum in order to diagnose motility disorders of the stomach and small intes- tine. A tube is passed through the nose, throat, esophagus, and stomach, until the tip lies in the small intestine. The tube senses when the muscles of the stomach and small intestine contract and squeeze it. The contractions are recorded by a com- puter and analyzed.