Sorry I didn't get to this sooner, but, assuming they are doing a trans rectal biopsy which I think is the most common. It can be done in office or hospital setting, my doc gave me a choice. I elected to do it in the office.

I was prescribed some heavy antibiotics to take a few days before and after. In the office they gave me another antibiotic injection. There's no polite way to say this so I won't try, they basically take a device and sort of shoe horn your anus open and work through there. They gave me a local anesthetic it wasn't all that painful, I'd call it uncomfortable, but very weird. They use a long syringe type device to take cores out of the prostate for testing, in my case 12, I've heard other numbers.

After the biopsy I didn't have much pain but the first bowel movement had some pain I wasn't expecting, that was a bit shocking. You may have some blood in your urine (I didn't) and you may see blood in your ejaculate, that I did have in varying degrees till the robotic surgery.

Best of Luck to you!