Travel insurance can be complicated. Even though my bowel issue doesn't fall under the pre-existing conditions the problem is in the small print. Under additional exclusions and limitations: Any medical condition for which prior to your day of departure and/or prior to booking your trip 1. you were awaiting the outcome of medical tests, the results of which show any irregularities or abnormalities. 2. future investigation , consultation with any physician, treatment or surgery (except routine monitoring) is recommended by a physician or planned before your trip.
This does not include regular check-ups or routine tests where no medical signs or symptoms existed or were found during the check-up.

That is the exact wording in my travel insurance. So it can be very tricky and you would not want to go on the trip and then have to file a claim and have it denied because of the above.
My GI specialist suggested I wait for 6 months with no issues before booking a trip which I am going to do. I am going back to him in 4 months but it will be routine monitoring. Hope it will work out.