This page is about your gastric emptying scan at Royal Brompton Hospital. It explains what will happen, how to prepare, and what to expect on the day.

A gastric emptying scan measures how quickly your stomach empties food into your intestines. This helps your specialist understand whether your stomach is working more slowly or more quickly than expected.

We know that having a scan can feel worrying, especially when it involves eating a test meal. This page explains what will happen, how to prepare, and what to expect on the day. Our team will support you throughout your visit.

What the scan involves

For this scan, we mix a very small amount of radioactive tracer with a meal, usually porridge. If you cannot tolerate porridge, we will offer an alternative meal.

The tracer is not absorbed by your stomach. It moves through your digestive system with the food. A gamma camera takes pictures to show how quickly the meal leaves your stomach and travels through your intestines.

The tracer does not cause any side effects.

What will happen on the day

When you arrive

• A technologist will prepare the meal and mix in the tracer.
• You will be asked to eat the meal slowly over up to ten minutes.
• We will give you gloves and a disposable apron in case any of the meal spills.

During the scan

• As soon as you finish the meal, we will take the first picture.
• You will lie on the scanning couch and need to stay as still as possible.
• 1 minute scans will be taken every 30 minutes for the first 2 hours.
• After this, 2 more scans will be taken, one at 3 hours and one at 4 hours after you start the meal.
• Between the 3 hour and 4 hour pictures, you may leave the department if you wish, but you must not eat, drink or smoke.

The gamma camera is similar in size to a CT scanner and quieter than an MRI scanner.

If your clothing has metal fastenings that cannot be removed, we may ask you to change into a gown.

How to prepare

A member of staff will call you before your appointment to check your medicines and any food allergies.

• You will be asked to stop any medicines that affect stomach emptying for 24 hours before the scan. Please call us before your appointment if you are not sure whether to stop taking your medication so we can advise you. 
• If you are unsure whether your medicines affect your stomach, tell us the names and we will advise you.
• You must not eat or drink anything for 8 hours before the scan.
• Because of the timing of the test, appointments are usually at the start of the working day.

Risks of radiation during a gastric emptying scan

The amount of radiation used during a gastric emptying scan is small and kept to a minimum. We believe that the benefits of having the scan far outweigh any risks.

The risk of a person getting cancer because of this radiation is very low, 1 in 100,000 to 1 in 10,000 people. This level of risk is very small compared with the overall lifetime chance of getting cancer. The overall lifetime chance of getting cancer is around 1 in 2 people. 

After the scan

• A doctor will check the images while you wait.
• Once the images are confirmed, you can go home.
• The radiation dose from this scan is very small.
• You do not need to make any changes to your routine.
• There are no contact restrictions after this scan.
• The tracer will not make you sleepy and will not affect your ability to drive.

Your results

A nuclear medicine consultant will review your scan and send the report to your referring specialist. The results will also be available on the hospital’s electronic system.

Your specialist doctor will discuss the results with you and explain any next steps.