Bowel transit time
Bowel transit time refers to how long it takes for the food to move from the mouth to the end of the intestine (anus).
This article talks about the medical test used to determine bowel transit time using a radiopaque marker testing.
Food passes from the stomach into the small intestine. In the small intestine all nutrient absorption occurs. Whatever has not been absorbed by the small intestine passes into the colon. In the colon most of the water is absorbed from the food residue. The residue is then eliminated from the body as feces.
How the Test is Performed
You will be asked to swallow multiple radiopaque markers (show up on x-ray) in a capsule, bead, or ring.
The movement of the marker in the digestive tract will be tracked using x-ray, done at set times over several days.
The number and location of markers are noted.
How to Prepare for the Test
You may not need to prepare for this test. However, your provider may recommend you follow a high-fiber diet. You will likely be asked to avoid laxatives, enemas, and other medicines that change the way your bowels function.
How the Test will Feel
You will not feel the capsule move through your digestive system.
Why the Test is Performed
The test helps determine bowel function. You may need this test done to evaluate the cause of constipation or other problems involving difficulty passing stool.
Normal Results
The bowel transit time varies, even in the same person.
- The average transit time through the colon in someone who is not constipated is 30 to 40 hours.
- Up to a maximum of 72 hours is still considered normal, although transit time in women may reach up to around 100 hours.
What Abnormal Results Mean
If more than 20% of the marker is present in the colon after 5 days, you may have slowed bowel function. The report will note in what area the markers appear to collect.
Risks
There are no risks.
Considerations
The bowel transit time test is rarely done these days. Instead, bowel transit is often measured with small probes called manometry. Your provider can tell you if this is needed for your condition.
References
Camilleri M. Disorders of gastrointestinal motility. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 127.
Iturrino JC, Lembo AJ. Constipation. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 19.
Rayner CK, Hughes PA. Small intestinal motor and sensory function and dysfunction. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 99.
Version Info
Last reviewed on: 7/30/2022
Reviewed by: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
