The sigmoid is the last part of your colon, right before the rectum. Depending on how old you are, a sigmoidoscopy doesn't quite seem necessary, based on your symptoms. The flexible sigmoidoscope is not as long as the colonoscope, and only goes partly up the colon. I believe it's more painful than a colonoscopy because they don't sedate you as much. But don't quote me on that - I've never had one, just a colonoscopy, which was a breeze. I would really question your doctor as to this test's relevance to your UPPER GI symptoms.
A sigmoid is a camera up ya rear end ,,,,,and after that youll feel like you wanna fart for around 2 hours ..the other symtoms sound like gastritis ..burning under the ribs , not like acid but like youd swalowed the contents of a car battery .bubbly knawing sensation...and feels like air has been pumped into you (not bloating sensation).with me it was on the left just under the ribs .and horror thoughts of "oh its like im bleeding inside" came to mind ..i would put a bet on it 70/30 im right...take care
BTW..iv had it down the throut and up the other end ....if you cant relax, then have a seditive ....i nearly strangled a nurse.:>))