Modifier 52 (Reduced services): Modifier 52 applies when "a service or procedure is partially reduced or eliminated at the physician’s discretion," according to CPT ’s Appendix A, "Modifiers." You should use modifier 52 when services your urologist performs are less than described by the code.
Modifier 53 (Discontinued procedure): You should append modifier 53 if the physician elects to terminate a surgical or diagnostic procedure "due to extenuating circumstances or those that threaten the well-being of the patient," according to CPT instructions. Note that you cannot use modifier 53 unless anesthesia has already been initiated.