It’s a test that measures how long it takes food to move through your system.
It uses a special pill or some other method to track how quickly your body moves food from your stomach to your small intestine and on to your colon before you poop it out.
Why Do You Get It?
If you’re experiencing constipation, diarrhea, bloating, heartburn, abdominal pain, nausea, and vomiting, your doctor might want to do a bowel transit time test. It can help them determine the cause of your discomfort.
The following things can affect how food moves through your GI tract:
- Irritable bowel syndrome (IBS)
- Functional dyspepsia (your stomach burns or feels full without a natural cause)
- Gastroparesis (your stomach takes a long time to empty but there’s no blockage)
- Chronic constipation
Your doctor also may want to do this test if you’re considering surgery for constipation.
How Is It Done?
A bowel transit time test typically means swallowing a pill with a wireless transmitter that sends signals to a small data receiver you wear. The signals from the pill tell your doctor how long it takes food to move through your digestive tract. It can also point to a problem in your stomach or small or large intestine.
Another way to measure bowel transit time is scintigraphy. In this test, you eat a meal or swallow a capsule labeled with a radioactive marker. This allows your doctor to follow the food or capsule’s progress through your stomach and gastrointestinal (GI) tract using a gamma camera.
Preparing for the Test
Before a bowel transit time test, you’ll need to fast for 8 hours. You should also tell your doctor what medications you’re on. They may tell you to stop taking them in the days leading up to the test. Certain pain medicines slow movement in your GI tract. Laxatives and stool softeners speed it up.
You’ll typically take the pill at the doctor’s office with water and a snack. After 30 minutes or so, you can go back to your normal activities.
The pill measures pH, temperature, and contractions as it moves through your stomach and GI tract. You won’t feel it moving through your body. Normally, your doctor will monitor you in a lab for about an hour after you take the pill.
For the next 3 to 5 days, you’ll be allowed to eat and drink like you normally would. You’ll be wearing the data receiver. Your doctor will ask you to push the button on the receiver at certain times. They’ll also ask you to keep a diary of meals, sleep, and bowel movements.
This test will give your doctor images at certain points to show how the radioactive food or capsule is moving through your system.
Within 5 days (plenty of time to complete the transit study, even if there are delays), the pill will come out with your poop. You’ll return the receiver to your doctor.
Who Shouldn’t Get This Test?
Your doctor may decide not to give you the bowel transit time test using the pill if you have Crohn’s disease or if you’ve had surgery in your GI tract before. In these cases, you may have narrow spots called strictures that make it difficult for the pill to pass.
This bowel transit time test also might not be right for you if you’ve got a bowel obstruction.
In these cases, you may do the scintigraphy test. That’s because the food labeled with the radioactive isotopes gets fully digested and turned into liquid. That makes it less likely to get stuck than a hard pill.
What Do the Results Mean?
If your bowel transit time test was done using the pill, your doctor will download the data from your receiver and analyze the results.
Once they find out how long the pill took to move from your stomach through various stages of your GI tract, they’ll be able to pinpoint the location of your problem and possibly the cause. That’ll help them to decide the best treatment for you.
A stomach that functions properly will empty in 4 to 6 hours. Food generally takes 5 hours to move through the small intestine and 10 to 59 hours to move through the colon.