A gastric emptying scan, also known as a gastric emptying study or test, is an exam that uses nuclear medicine to determine how fast food leaves the stomach.
It differs from a standard X-ray in that it uses a small amount of radioactive material to emit photon energy. The energy is detected by a gamma camera, which creates a computerized image.
The gastric emptying scan is the most commonly used test to diagnose gastroparesis. There are several variations of the test depending on which medical center performs it.
For this test, the patient is instructed to not eat or drink anything after midnight the night before and to avoid certain medications the day of the test. Some meds can affect the accuracy of the test results.
Before the test, the patient is given a meal with a trace of radioactive markers in it. The most common food used is eggs and toast, but often oatmeal or other foods are provided.
A small amount of water or juice may also accompany the meal. This meal should be eaten within a certain timeframe in order to ensure the most accurate results.
What Is a Gastric Emptying Scan Used For?
Gastric emptying scans are often used to diagnose gastroparesis, a condition in which the stomach’s muscles don’t work properly. This results in a delay in sending food to the small intestine.
Doctors order the scans for adults and children who frequently vomit, feel bloated after eating, or complain of abdominal pain. Weight loss or changes in sugar levels are also symptoms of gastroparesis.
Where and How Will the Test Be Administered?
Gastric emptying scans take place at hospitals. They are performed by professionals trained in nuclear medicine or radiology.
Before the scan, the patient will eat a meal. This is usually scrambled eggs treated with a small amount of tasteless radioactive material.
For children who refuse to eat, the radioactive substance can be administered through a nasal feeding tube or gastrostomy tube.
Infants and toddlers are usually given formula, milk, or juice. The radioactive substance allows the camera to follow the food through the digestive process.
The patient will lie on a table while the camera takes pictures. Over the course of three to five hours, four to six scans lasting about a minute each will be taken.
In the case of infants and toddlers, the camera takes continuous images for about an hour. Some hospitals use a gamma camera that takes pictures while the patient is standing.
It is important to remain still during the scan.
What Are the Risks of a Gastric Emptying Scan?
A person will experience a small amount of radiation exposure from the material put in the food eaten before the scan.
This is not considered dangerous, unless a woman is breast-feeding, pregnant, or planning to become pregnant. Anyone in these circumstances should tell her doctor before having a gastric emptying scan.
How Does a Patient Prepare for Gastric Emptying Scan?
Other than the radioactive meal before the scan, patients should not eat or drink anything for four to six hours before the test.
It’s a good idea to bring books to read or a personal listening device to pass the time. A parent might want to bring their child’s favorite toy or pacifier.
Be sure to let the technician know if you are taking any medications or have any health complications, such as diabetes.
During the test
The GES typically lasts anywhere from 90 minutes to 6 hours. Images of the rate at which the food is digested are taken at certain intervals, often at the first half hour, then every half hour-hour after that. In most instances, the patient is allowed to return to the waiting room in between images.
It is believed that the 4-6 hour tests are the most accurate. Many people may have normal results with the 90 minute test, but show delayed emptying during the 4-6 hour version.
After the test
Nothing is required after the test is over. The patient may return to normal meds, activity, and eating as instructed by his/her physician. Test results may take a couple of days to analyze.
A negative result means the meal moved through the stomach at a normal rate and is not suggestive of gastroparesis.
If the results are positive, gastroparesis is the first suspicion and the physician may request additional testing to rule out additional causes for delayed emptying such as blockages, certain medications, or tumors.