Difficult to say without examination.
Possibilities can be an effect of scar tissue, or perhaps an infection.
There is the chance that a surgical procedure can better define the cause - but as your urologist mentioned, there are no guarantees.
Infection is possible, and can be initially evaluated with a urinalysis.
These options can be discussed with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
http://www.straightfromthedoc.com