It must be stress or something but one year when I had 2x surgeries, my period arrived literally on the day of the surgery both times. You can't wear a tampon because of the risk of toxic shock syndrome if you end up unconscious for longer than expected. I just mentioned it to the nurse who helps you get ready, it wasn't a big deal, happens all the time. In fact so much not a big deal that I can't even remember very well but I think they might have given me a blue protective thing under my bum once I ws on the table. Anyway, weird thing was both times the surgery must've been such a shock to my system that it literally stopped the period dead in its tracks. Lol.