I agree with @northoftheborder in that a cleanse will not remove the bacteria. One study a few years ago (Hopkins?) showed that a simple povidone iodine suppository inserted one hour before the procedure cut the risk of infection by something like 98%. Please research this! Unfortunately no one does this simple step….
But it may be something for you to do on your own if you think you are going to go ahead with the trans rectal biopsy, in spite of all the posters who have suggested the trans perineal option. Have a feeling your urologist might scoff at the idea but maybe your primary care doc can get you an RX if one is necessary.
Also, I did have trabeculation in my bladder but it all went away after the obstruction (prostate!) was removed.