Body Surface Gastric Mapping (Gastric Alimetry®)

BSGM uses a recording device placed on the skin to measure electrical activity in the stomach. It is similar to an ECG, which checks your heart, but instead of looking at your heart, it looks at how your stomach is working.

This test helps your doctor understand how your stomach moves (motility), the electrical signals that control those movements, and how those signals relate to any symptoms you are having.

Recording of the electrical signals is done whilst your stomach is empty, when you eat and then after you have eaten.

BSGM can be used to help investigate stomach (gastric) symptoms such as:

• Early satiety (feeling full very quickly)
• Vomiting
• Stomach pain
• Nausea

The test can help find out if your symptoms are being caused by problems in your stomach.

The test involves placing a large sticky patch with electrodes (sensors) onto the skin that lies above the stomach. A recording device is also attached to the patch. First, we clean the skin and then we take some measurements and put some small marks on your stomach to know where to place the patch.

You then recline in a chair and recording takes place for 4 hours and 30 minutes. During this time you must stay still and relax, though you can get up for a few minutes to go to the toilet or to stretch out. You will be given a computer tablet to record your symptoms on throughout the test. You will also be given some questionnaires to complete to help us gain more information about your symptoms.

The appointment takes around 5 hours in total and is split up into:

• 15 minutes of preparation and speaking with the clinician
• 30 minutes recording with an empty stomach
• About 10 minutes to eat a small meal we provide for you
• 4 hours of recording after finishing the meal
• 15 minutes to finish and remove the sticker.

The meal provided is a protein shake-like drink and a cereal bar. If you have any special dietary requirements or allergies (or are diabetic), please let us know and we will adjust the meal if needed. It is important that you eat all or nearly all of this meal. This may be difficult and cause symptoms, but it is important for the test, and seeing and recording your symptoms as they happen helps us get a better understanding of what is causing them.

In general the test is very safe and well tolerated. Common risks or side effects include:

• Mild redness on the skin due to exfoliation or a mild itch or rash. This usually goes away within 1-2 days.
• Some stiffness or discomfort due sitting in one position for a long period of time.
• After eating you may experience your typical symptoms, but this is important for the test.

Rare risks or side effects include:

• An allergic reaction to the patch or adhesive.
• An allergic reaction to the food provided – please inform us if you have any food allergies.

There are other tests that look at the emptying of your stomach such as gastric scintigraphy and barium studies. While this test is similar it does not provide information about the activity of the nerves or muscles.

Please let us know before the test if you have:

• Any open wounds, skin cuts, abrasions or infections on the abdomen
• An allergy to plasters, tape, adhesive or adhesive remover
• Any dietary requirements or allergies

You will have to stop some medications for 1-2 days prior to the test. These will include:

• Medications that effect stomach and gut motility e.g. Metoclopramide, erythromycin, Buscopan, prucalopride, domperidone
• Opioid pain killers such as Morphine, Zapain, Tramadol, Codeine, co-codamol, oxycodone, buprenorphine

This will be discussed with you beforehand.

You must fast for at least 6 hours prior the test. This means no food or liquids (including water) before the test, though if you take any regular medications that must be taken in the morning, you can take these with a sip of water before the test.

On the day of the test:

• Wear loose comfortable clothing that allows easy access to your stomach (we recommend not wearing a dress).
• Please do not wear a wired bra as this affects the electrodes.
• Please do not apply lotion or moisturiser to the stomach.
• If you have any piercings on the stomach, please remove these.
• We may need to shave your stomach if there is excess hair.

Please bring something to entertain yourself during the test such as a tablet, laptop, book, movie with headphones or some work. You are not allowed to sleep during the test and talking must also be limited so it is not recommended to bring another person.

The patch will be removed, and you are then free to resume your normal activities, including eating and drinking as you normally would, and you can resume taking any medications as normal.

The results will be sent to your referring doctor, and they will contact you with the next steps.

Pathway Co-ordinator (Monday to Friday 09:00-17:00)
Direct line: 0203 447 9130 / 0203 456 2060
E-mail: uclh.giphysiology@nhs.net

Switchboard: 0845 155 5000 / 020 3456 7890

Address: GI Physiology Unit, Lower Ground Floor, EGA Wing, University College Hospital, London, WC1E 6DB