The colonoscopy won't find celiac you have to have a endoscopy and they take a biopsy. You have to have been eating gluten for a few weeks before the test. I have had diarrhea for over 30 years. No celiac has been found but I am gluten intolerant. It's a horrible and embarrassing problem. I just came back from a family vacation and it's a good thing the house we rented had 5 bathrooms. Next year the family is talking about renting a house in France. How do people travel out of the country with this.