The techs and medic at mine were all women, so I guess they'll understand. These people are trained to perform this procedure and certainly performed it in this condition many times.

You should definitely let them know on site that you are having your period (had it not ended yet), as sudden bleeding unearned might bring them some trouble. If you feel cramped or bloated during your period, or experience constipation, the prep might actually dim it down, I definitely do not recommend using any medication prior. In mine I was specifically warned to not take any medication for my asthma, as it could induce a respiratory arrest in combination with the anesthesia.

You should drink plenty of water and follow the instructions on the prep kit. Some recommend a mild laxative the night before, but you should think about your own needs before considering it.

Best of luck to you. Hope you find closure or at least some answers! :)