Colonic Transit Study (Sitz Marker Test)

This test uses tiny radio-opaque ‘markers’ to test how fast food is moving through the colon. It is most often used with patients who are suffering from chronic constipation.


  • DO NOT take laxatives, enemas, or suppositories during the week this test is in progress.
  • You may eat and drink as usual.
  • We will need to have you come in for an abdominal x-ray a specific number of days after you swallow the radiopaque markers depending on your location, per the following instructions.
  • You will need an x-ray in exactly 5 full days after you swallow the radiopaque markers. Do not swallow the Sitz Markers on Tuesday or Wednesday because most x-ray centers are closed on the weekend when you would need your x-ray done. If you swallow the capsule on:
    • Monday, you need an x-ray on Friday
    • Thursday, you need an x-ray on Monday
    • Friday, you need an x-ray on Tuesday
    • Saturday, you need an x-ray on Wednesday
    • Sunday, you need an x-ray on Thursday


  • You will be provided with a capsule which contains 24 radiopaque markers to swallow. This capsule contains small markers which will show up on x-ray and let the doctors track their progress through your colon.
  • You will need to be scheduled for an abdominal x-ray on certain day(s) after you swallow the radiopaque markers to see if any of the markers are left in your colon. Please see more specific timing instructions by location under Preparation.


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