Baboudjian M, et al. - Researchers examined how a standardized diagnostic flexible ureteroscopy (DFU) technique before radical nephroureterectomy (RNU) for urothelial carcinoma, influence the risk of bladder recurrence. They performed a retrospective monocenter study identifying 171 patients who underwent RNU for upper tract urothelial carcinoma (UTUC). patients were identified. Owing to a history of bladder cancer before RNU or neo-adjuvant/adjuvant chemotherapy, they excluded 78 patients. According to pre-RNU ureteroscopy (DFU + 70 patients) or no pre-RNU ureteroscopy (DFU—23 patients), stratification of 93 included patients was done. Observations revealed that despite technical precautions to avoid contact of bladder mucosa with contaminated urine from the upper urinary tract, bladder recurrence after diagnostic ureteroscopy + nephroureterectomy was high. They recommend investigating post-DFU endovesical instillation.