I have actually experienced this sort of situation. Now it seems quite funny, at the moment of its occurrence I assure you it was not. Fortunately no dire consequences manifested themselves in my situation. I was taking a Q&A session at the time, as a person was asking a question I interrupted him by exclaiming excuse me, excuse me all, I'll be right back, and immediately left the conference room and walked at a rather fast pace to the nearest restroom. When I returned, the meeting had shifted to another topic which did not require my direct participation, I excused my self with my superior, gathered my items and returned to my office. When the meeting ended I did make it a point to apologize to the others present for my abrupt exit. Naturally I did not reveal the reason, but it was assumed that it was health related.

Between running out and making a dash for the bathroom or suffering whatever the consequences would be otherwise, I will always choose running out. I figure one can always apologize if someone thought you rude in that brief instance, the other scenario I would not even want to think about.