World Heart Day
Chronic constipation is a common digestive problem that affects millions of people worldwide, often leading to discomfort, bloating, and difficulty with daily activities. When lifestyle changes, fiber supplements, or laxatives do not solve the problem, doctors turn to specialized tests to uncover the root cause. One of the most reliable methods is the colon transit study, also known as the Sitz marker test.
This test measures how quickly stool moves through the large intestine by tracking small radiopaque markers that are visible on X-rays. It helps doctors determine whether constipation is caused by slow movement of stool through the colon (slow-transit constipation) or by pelvic floor dysfunction (outlet obstruction constipation).
In this guide, we will explain what a colon transit study is, why it is performed, how the procedure works, what the results mean, and its benefits and limitations. You will also learn how the test is performed at Alliance Hospital BD, where advanced diagnostic facilities ensure accurate results and effective treatment planning.
A colon transit study, also known as a Sitz marker test or colonic transit time test, is a diagnostic procedure used to measure how quickly stool moves through the large intestine. It helps determine whether chronic constipation is caused by slow movement of stool through the colon (slow-transit constipation) or by pelvic floor dysfunction (outlet obstruction constipation).
The test involves swallowing capsules that contain tiny radiopaque markers (visible on X-rays). Over several days, X-rays are taken to track how many markers remain in the colon and where they are located. This simple, non-invasive test provides valuable insight into bowel function.
Doctors recommend this test when a patient has long-term constipation that does not improve with diet changes, fiber supplements, or laxatives.
Reasons for performing a colon transit study include:
Chronic constipation (lasting for months or years)
Unexplained abdominal bloating or discomfort
Incomplete bowel movements despite strong urges
Evaluating colon motility disorders such as slow-transit constipation
Differentiating outlet obstruction from slow-transit constipation
Assessing effectiveness of treatment after surgery or medication
The results help guide targeted treatment, ensuring patients avoid unnecessary or ineffective therapies.
The colon transit study is safe, non-invasive, and easy to perform.
Step 1 – Swallowing the Capsule
The patient swallows a capsule containing 20–24 tiny radiopaque markers.
These markers are harmless and pass through the digestive tract with stool.
Step 2 – Tracking the Markers
Abdominal X-rays are taken on specific days (usually day 3 and day 5, sometimes up to day 7).
Doctors count how many markers remain in the colon and where they are located.
Step 3 – Analyzing Results
If most markers remain spread throughout the colon → slow-transit constipation is likely.
If markers cluster near the rectum → pelvic floor dysfunction is suspected.
If most markers are passed → bowel movement is normal.
Patients can continue daily activities, normal diet, and medications (unless told otherwise).
The colon transit study provides clear evidence about bowel movement speed and patterns.
Normal transit: Most markers are passed within 5 days.
Slow-transit constipation: Markers are scattered throughout the colon, showing that stool is moving very slowly.
Outlet obstruction constipation: Markers collect near the rectum, suggesting the muscles are not relaxing properly.
Mixed patterns: Some patients have both slow movement and outlet dysfunction.
These findings allow doctors to recommend specific therapies such as biofeedback, pelvic floor therapy, medications, or surgery.
Simple and non-invasive – No anesthesia or complex preparation.
Low radiation exposure – Minimal compared to CT scans.
Clear differentiation between slow-transit constipation and outlet dysfunction.
Guides personalized treatment, preventing trial-and-error approaches.
Takes several days – Requires multiple visits for X-rays.
Radiation exposure – Although minimal, may not be suitable for pregnant women.
Does not show structural problems – Must be combined with other tests (e.g., defecography, manometry) for full evaluation.
At Alliance Hospital BD, we provide advanced diagnostic services for patients struggling with chronic constipation. Our colon transit study program offers:
Safe and accurate Sitz marker testing
Modern digital X-ray facilities
Expert interpretation by gastroenterologists and colorectal specialists
Integration with other diagnostic tools (defecography, anorectal manometry, balloon expulsion test)
Personalized treatment recommendations based on results
We ensure that patients not only receive a diagnosis but also a clear management plan for long-term relief.
If you are experiencing chronic constipation, incomplete evacuation, or unexplained abdominal discomfort, a colon transit study could be the key to finding the cause.
📞 Contact Alliance Hospital BD today to schedule your test and take the first step toward restoring healthy bowel function.
The colon transit study is a simple yet powerful test that helps doctors understand the cause of chronic constipation. By tracking the movement of radiopaque markers through the colon, it differentiates between slow-transit constipation and pelvic floor dysfunction, guiding precise treatment.
At Alliance Hospital BD, we combine advanced diagnostic tests with expert medical care, ensuring that patients receive accurate results and effective treatment plans to improve their quality of life.
