Originally Posted by mrsD

I believe the sampling is from the villi in the intestine.

From reading the gluten posts for years, I think even some
biopsies can be negative and people still report the GF diet helps anyway. This is because the intestine is not all inflamed equally and patches may be missed.

You'll have to ask the doctor, if he plans on going past the stomach into the small intestine. The scope will show if
the stomach has inflammation or ulcers, etc.

Glenn knows more about the testing than I do.