I can only offer a layman's opinion. Unless the patient is severely "impacted," I would think a full rectum might slow down, but not stop, absorption. I also think there are many factors for surgeons to consider in deciding pre-op, and post-op needs. What part of the body are we operating on? How long will the actual surgery take? What is the patient's general condition otherwise? Age would be a factor.
I've had 5 major surgeries in my life. I mean those that required full general anesthesia. The last one surprised me. My prostrate removal came 14 years after my last my last such operation. I mean, they are going to open my abdomen, and I was NOT given a suppsoitory, or an enema?
I will say to all of you males: IF you are ever scheduled for a biopsy of your prostrate, do NOT rely upon the "fleet" that will ordered at home, either the night before, or that morning, Take a good common enema instead, in the MORNING. I took the fleet, and when the biopsy was finished, I was left with a ROYAL MESS. (This biopsy is done through your rectum. It is also more painful than the doctor will say it is to be. Walt