Gastric Emptying Study

A gastric emptying study, also called gastric emptying scintigraphy, is the standard test that confirms gastroparesis. You eat a small meal that holds a trace of safe radioactive material, and a scanner measures how much remains in your stomach over about four hours. If too much food stays behind, the stomach is emptying too slowly.

What is a gastric emptying study?

A gastric emptying study measures the one thing that defines gastroparesis: a stomach that empties too slowly when nothing is blocking it. According to the National Institute of Diabetes and Digestive and Kidney Diseases, you eat a bland meal, usually eggs or an egg substitute, that holds a small and safe amount of radioactive material, and a camera then tracks how quickly the meal leaves your stomach. A doctor orders the test after reviewing your symptoms and ruling out a blockage, and it is the most reliable way to confirm the diagnosis. Our guide to gastroparesis diagnosis shows where this test fits among the others.

What happens during a gastric emptying study?

The test is simple and painless. You are given a standard low-fat meal, typically scrambled egg whites mixed with a small amount of a radioactive tracer, along with toast and water, and you are asked to finish it within about ten minutes so the timing starts cleanly. A special camera then scans your abdomen for roughly a minute at a time at set points, usually right after the meal and again at one, two, and four hours. Between scans you sit and wait. The radiation involved is very low, similar to other routine imaging, and it leaves your body naturally over the next day or two. Most of the appointment is simply waiting, so many people bring something to read.

How do you prepare for a gastric emptying study?

A few steps protect the accuracy of the result. You will be asked not to eat or drink for at least four hours beforehand, and the test is often scheduled in the morning so you can fast overnight. Some medicines slow the stomach and can make a normal result look delayed, so your doctor may have you pause certain drugs for about two days before the test, in particular opioid pain medicines, prokinetics, and some antidepressants. Never stop a prescribed medicine on your own; follow the instructions your care team gives you. Smoking also slows emptying, so avoid it on the day of the test.

If you have diabetes, the staff will check your blood sugar first and may reschedule if it is too high, because high blood sugar slows the stomach and can skew the reading, so bring your glucose monitor and insulin. Tell the team about any food allergies, since the meal usually contains egg.

What do the results mean?

Results are reported as the share of the meal still in your stomach at each time point. Emptying is considered normal when about 90% of the meal has left the stomach by four hours. It is considered delayed, the finding that confirms gastroparesis, when more than 60% remains at two hours or more than 10% remains at four hours.

The amount left behind also grades how severe the delay is:

• roughly 11% to 20% retained at four hours is mild
• 21% to 35% is moderate
• 36% to 50% is severe
• more than 50% is very severe

This grading helps your doctor judge how closely to manage your care. A clear result is often a relief after months of unexplained symptoms, because it points toward a plan. See gastroparesis treatment for what usually comes next.

Why does the test take four hours?

Shorter scans miss cases. For years many centers imaged for only one or two hours, but studies found that stopping at one hour overlooks roughly a third of the people whose delayed emptying shows up by four hours. The full four-hour study is now the recommended standard precisely because it catches these slower cases. If your appointment is set for the morning and runs into the afternoon, that length is by design, not a sign of a problem.

Are there other ways to measure stomach emptying?

The scan is the most common test, but it is not the only one. A breath test has you eat a meal containing a harmless marker that is later measured in your breath to estimate emptying speed, and a wireless motility capsule, a small device you swallow, records how fast food moves through the stomach and intestines. The SmartPill, the wireless motility capsule long used for this purpose, was discontinued in 2023; newer capsules such as the Atmo capsule are emerging as replacements, though availability varies by center. Your doctor chooses the approach that fits your situation and the equipment available. Our page on gastroparesis diagnosis compares these options in more detail.

Sources

Reviewed by Owen Hastings.

• NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases), Diagnosis of Gastroparesis (niddk.nih.gov), last reviewed January 2018, for the gastric emptying scan, the meal, and the roughly four-hour scan time.
• Cleveland Clinic, Gastric Emptying Study (my.clevelandclinic.org), for the preparation steps, the meal and scanning schedule, the low radiation dose, and the normal and delayed result ranges.
• Consensus Recommendations for Gastric Emptying Scintigraphy, a joint report of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine (Journal of Nuclear Medicine Technology, 2008), for the standardized low-fat egg-white meal, imaging at zero, one, two, and four hours, the thresholds of more than 60% retention at two hours and more than 10% at four hours, and the severity grades.
• American College of Gastroenterology Clinical Guideline on Gastroparesis (2022), for the recommended four-hour protocol and the customary practice of pausing motility-affecting medicines for about 48 hours before the test.
• Becker's ASC, Medtronic to discontinue GI SmartPill after 17 years (beckersasc.com), 2023, for the SmartPill discontinuation.

This page is general health information, not medical advice. Talk to your doctor about your own care. Last reviewed July 2026.