Antro-duodenal Motility Study

An antro-duodenal motility study is used to evaluate the ability of the muscles of the stomach and the first portion of the small intestine (duodenum) to contract. Conditions in which there is an abnormal contraction of the muscles of the stomach and the small intestine are referred to as motility disorders. Therefore, an antro-duodenal motility study is used to identify motility disorders.

An antro-duodenal motility study is used to diagnose a motility disorder of the stomach or small intestine, that is, a condition of abnormal function of the muscles of the stomach and/or small intestine. Such abnormal function usually is suspected when there are symptoms and signs of obstruction to or delayed flow of food through the stomach and intestines. These symptoms usually are nausea, vomiting, and intestinal distention (enlargement). The obstruction is a direct result of the inability of the abnormally functioning muscles to propel food through the stomach and intestines. One common cause of motility disorders of the stomach and intestines is diabetes mellitus.

For an antro-duodenal motility study, a thin tube (one-eighth inch in diameter) is passed through the nose, down the esophagus, through the stomach, and into the duodenum, the first part of the small intestine.

Sensors in the tube measure the amount of pressure generated when the muscles of the stomach and intestine contract and squeeze tightly around the tube; the greater the contraction of the muscles, the greater the pressure sensed by the tube.

All contractions are recorded by a computer for analysis. Contractions are recorded at rest for up to several hours and for one or two hours after a meal. Thus, a study may take up to six hours.

Normally, there are characteristic patterns of contraction of the stomach and duodenum during fasting periods and after meals. In patients with motility problems of the stomach and/or small intestine, the characteristic patterns are abnormal or completely absent. Such patients may be treated with drugs to stimulate contraction, such as metoclopramide (Reglan).

There are no important side effects; however, the tube can become quite irritating after several hours, giving the patient a sore throat. Occasionally, the tube also causes nasal irritation. Within 24 hours after the tube is removed, the irritation disappears.

Other tests can help with the evaluation of motility disorders, including upper gastrointestinal X-rays, gastric emptying studies, and electrogastrograms. The most recent device for determining gastrointestinal motility is a radiotelemetry capsule (Smartpill) that senses the pressure generated when the stomach or intestinal muscles contract around it. The capsule is swallowed, and it then travels through the stomach and intestines. While it is traveling, it continually senses the pressure around it and transmits this information wirelessly to a receiver worn on the outside of the body. Later, the data is downloaded from the recorder and analyzed.