Welcome to the forum, Trotters.
Did the surgeon do a loose or floppy wrap? I had a Toupet, which is not terribly tight, and couldn't burp for most of a year. If after you get the pH test and it shows acid, that might mean it was too loose. Maybe. I'm not a doctor!
Did the doc mean there would be zero acid, or that the pH would read zero if there was acid.
I don't think gas is measured or would have anything to do with a pH test. I'm not a chemist either.