# Colonic Transit Tests - not reliable



## tummyrumbles (Aug 14, 2005)

This is a very interesting study which shows that colonic transit tests (using radio-opaque markers) can sometimes get it wrong.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3221847/

Interpretation of the tests are based on the location of the markers throughout the colon.

A young girl with a history of functional constipation had this test which showed retention of these markers. The doctors performed a colonoscopy with the intention to operate to remove the impacted faeces. They found to their surprise the colon was empty. The markers had adhered to the sticky mucus of the colon wall.

This study shows that markers do not always mix appropriately with faeces. If doctors had just relied on the CTT testing and xrays, faecel impaction would have been presumed and therapy would have been based on these results. You would expect stool to show up on xrays though.


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## annie7 (Aug 16, 2002)

yes, this is interesting isn't it.

i happened to read this article right before i had my sitz. and my gastro actually brought this type of situation up when we were discussing my taking the test.. none of my markers were clustered like this. i saw the x-ray on the screen and have a copy. my colon was totally full of stool when i was x-rayed since i had not had a BM at all during the test and had become impacted--or maybe obstructed since I couldn't even pass gas. the markers were all in the stool. i doubt if they could have become clustered and stuck in the colonic wall because i was so packed with stool.

i said something to the radiologist too about this study and he told me they were trained to recognize this type of clustering thing. so all that was reassuring to hear.

yes, you're right--stool shows up on x-rays.

but yes i can see where this clustering sort of thing could happen with an empty colon like that girl had. mine was anything but--lol...


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## Kathleen M. (Nov 16, 1999)

Every medical test has the potential for false positives and false negatives. That doesn't mean all of them are unreliable. That is why often there are follow up tests between the first evidence of something and the treatment for the something.

It would be weird if this was the one test in all the world that never had a false positive or false negative. Typically to be approved and used in humans the rate of false positives and false negatives has to be statistically low enough to make them mostly reliable most of the time.

This is why there are sometimes controversies about screening healthy people for some diseases rather than just people with some kind of symptom or indication of an issue. Where do you balance early detection with how much unnecessary pain and suffering do you cause to how many people.


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## tummyrumbles (Aug 14, 2005)

Thanks for the replies. Yes, even though no test is 100% reliable it can be an important test and would confirm constipation if xrays weren't enough. It was puzzling how the girl complained of pain and low bowel movements yet her colon was empty. Maybe the pain was from gas. It was a very interesting study anyway.


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