A gastric emptying study measures the rate at which food leaves the stomach to pass into the small intestine. Its purpose is to investigate patients whose symptoms are thought to arise from problems where the stomach empties too slowly or too quickly. The procedure involves the patient swallowing a small quantity of a radioactive substance. Then, for a period of up to three hours, a radiation scanner is used to measure the level of radioactivity in the stomach. In this way, the gastric emptying study allows the doctors to calculate an individual's rate of stomach emptying, which can be compared with normal values.
Symptoms which might lead to a patient having a gastric emptying study could include feeling unusually full after eating or experiencing nausea or vomiting. These symptoms are more likely if the stomach is emptying too slowly, but, in cases where emptying occurs too quickly, symptoms of dizziness, weakness and diarrhea may occur after meals. Some patients may have stomach pain, and, if abnormal digestion is occurring in a child, there may be a failure to grow and gain weight normally. Conditions which may cause abnormal gastric emptying include gastric outlet obstruction, where the section of gut leading out of the stomach is blocked, and gastroparesis, where the stomach muscles do not function normally.
Before a gastric emptying study, the patient is given a meal which combines both solids and liquids. A common example might be scrambled eggs with toast and a drink of milk or water. The meal is prepared by a technician who mixes into the food the small amount of radioactive substance required for the study. Levels of radioactivity during the procedure are very low and should not cause any side effects, but women who are pregnant or breast-feeding should not participate, as there is a small risk of harm to the fetus.
The test is carried out with the patient wearing a gown and arranged in a semi-reclining position on a bed, with the back supported. A scanner is fixed in place over the stomach to measure the levels of radioactivity, and it may be necessary to remain still for the duration of the procedure. If a visit to the bathroom is urgently required, the scanner may be stopped until the patient returns. A member of the staff stays with the patient throughout the procedure. After a gastric emptying study is completed, patients should feel quite normal and should be able to travel home by themselves.