Why is it necessary for me to take a bowel prep before having a hysterectomy?

Yes. It is in your best interest to do so just incase an injury occurs to your colon during the surgery, it can be repaired without the need to have a colostomy.
As a precaution. In the unlikely event that there sould be an inadvertent bowel injury which would require bowel repair...If bowel is prepped less likely to have infection if repair is required. Hope this helps.