I have had 4 abdominal surgeries with 3 different surgeons and all required a bowel prep before they'd go in. They said it was for my safety, an empty bowel lies flat and not much leaks out in case of an accidental nick.
One of our local gyn surgeons did not require his patients to do bowel preps. He can not longer practice in 3 of the 4 local hospitals and a woman I know will be getting millions from him because he perforated her bowel during surgery and since he hadn't required a bowel prep, she almost died. Her attorney proved that bowel preps before abdominal surgery were common practice.
I don't mean to scare you, I just worry when I hear a woman say her doc doesn't require a bowel prep before a hyst. You might want to do one anyway.