I only know that in my son's case they did biopsy for celiac disease during the colonoscopy. His was negative. That said, based on what I've read, a negative biopsy may not be definitive. I think it was this article or another on the same web site that said even the biopsy is not without its accuracy issues.
Mom to 16 year old son diagnosed in June, 2007.
Omega 3s, digestive enzymes, probiotics, vit. C, calcium w/D3, a good multivitamin and SCD legal yogurt
Started The Maker's Diet in Sept. '07. Gradually learning/using more Specific Carbohydrate Diet (SCD) recipes, too! (cooking challenged)