--should be able at least not only to look at what is going on in the stomach, but in the duodenum, which does contain villi and from which samples can be taken.

Sometimes, evidence of frank celiac may be found there. But, as noted, the damage to villi may be patchy, and may occur farther down the small intestine. And a standard endoscopy may not get that far down--for one thing, a different, smaller scope may need to be used.

There were a spate of recent articles referencing a study concluding underdiagnosis of celiac due to lack of sufficient villous samples taken on "standard" small intestine biopsies--here's one link to it (and it gives the original study reference):

http://www.stonehearthnewsletters.co...nored/updates/