I had an upper GI barium swallow. Once the doctor saw what I have--the twisted stomach and all the rest--
He had me lie on my RIGHT side and drink more, and could then watch the stuff reflux even.

My own internist said only about 5% of Xray studies actually show the reflux this way, and it was probably because my stomach was twisted as well. I have my pylorus (the end part of the stomach twisted 90 degrees and emptying in my back.

Hiatal hernias can come from frequent vomiting...which I had as a child, or mine may be part of the birth defect. They don't really know in my case. But hiatal hernias do tend to be somewhat common. Getting up, changing position, lying on my left side, having hubby rub my back, will all minimize discomfort when it happens. I really can't eat large amounts of food either, like at holidays. Avoid chocolate, and high fat meals, as this tends to slow stomach emptying. Coffee is completely out of my life too.

However, I've learned to control things so the vomiting is not common anymore. But when I was younger... my "spells" were very alarming and uncomfortable. GAS is my enemy. I avoid
carbonated drinks, and cabbage and most beans because of it.
Sometimes I use simethecone to break it up. Since using Kefir,
the gas problem is less. The probiotics in it seem to help with it.