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Colonoscopy and Bowel Habits

Can having a colonoscopy cause a change in bowel habit?

Eight months ago I had a screening colonoscopy that came back normal. Up to that point I was a physically very fit and healthy male in my 70's. But after the colonoscopy I immediately began experiencing severe constipation. I had never had this before. My doctor prescribed a fiber supplement which did not help. He also performed an MRI which came back negative. No one knows what is wrong or how to treat this. My life has changed dramatically since this has happened and I am no longer able to function normally. For all practical purposes this has made me a prisoner in my home. What could have caused this change during a colonoscopy?


Answer – There is no straight-forward answer to this question. In my practice I see mostly patients with functional GI disorders and I have observed that it is not that uncommon for patients with irritable bowel syndrome (IBS) to say that colonoscopy seems to upset their condition.  Fortunately, this is usually only short term but occasionally some patients can continue suffering for a considerable period of time.  The cause of this problem is uncertain, but in my experience it is not due to incompetence on the part of the colonoscopist. 

My particular view is it could be something to do with the preparation for the colonoscopy, which usually involves the use of a strong laxative.  We have shown in my laboratory that the administration of a laxative can sensitize the bowel, even in people without IBS, so one could imagine that it could cause even more of a problem in someone whose bowel is already sensitive as is the case in IBS.  On the other hand, many IBS patients with constipation as their predominant bowel symptom can only function if they are taking a laxative on a regular basis. 

Obviously it would be nice if one could prevent this problem, but at the present time there is no way of predicting who will and who will not react badly to a colonoscopy.  For persons with IBS it may be worth considering being rather cautious with laxatives when diarrhea is the predominant bowel symptom and it would their doctor to know if they ever had a tendency to diarrhea before the examination.  Finally, it is important to remember that the gut can take months rather than weeks to recover from any form of insult, and so there is still plenty of time for you to get better. 

Peter Whorwell, MD


Last modified on September 12, 2014 at 12:55:54 PM