Gastric Emptying Study
Bhupinder Anand, MD
What is a gastric emptying study?
The most common type of gastric emptying study is a procedure that is done by nuclear medicine physicians using radioactive chemicals that measures the speed with which food empties from the stomach and enters the small intestine. Gastric emptying studies are used for evaluating patients who are having symptoms that may be due to slow and, less commonly, rapid emptying of the stomach. The symptoms of slow emptying are primarily nausea, vomiting, and abdominal fullness after eating. The symptoms of rapid emptying are diarrhea, weakness, or light-headedness after eating.
How is a gastric emptying study done?
For a gastric emptying study, a patient eats a meal in which the solid component of the meal (for example, scrambled eggs), the liquid component of the meal (for example, water), or both, are mixed with a small amount of radioactive material. A scanner (acting like a Geiger counter) is placed over the patient's stomach to monitor the amount of radioactivity in the stomach for several hours after the test meal is eaten. As the radioactively-labeled food empties from the stomach, the amount of radioactivity in the stomach decreases. The rate at which the radioactivity leaves the stomach reflects the rate at which food is emptying from the stomach
Some medications such as narcotic pain relievers and anticholinergic medications can cause a delay in emptying of the stomach, while other medications such as metoclopramide (Reglan) and erythromycin can cause rapid emptying of the stomach. Medications that slow emptying of the stomach can give a falsely abnormal test result, while medications that speed up emptying of the stomach can give a falsely normal result. Therefore, medications that affect emptying of the stomach should be withheld for 48-72 hours before performing emptying studies.
Abnormally high blood glucose (sugar) levels also can slow emptying of the stomach. Therefore, it is important to control blood glucose levels to near normal levels before performing emptying studies in patients with diabetes who are prone to develop high blood glucose levels.