Complete duplex ureter with ureterocele and multiple large stones in the lower ureter: a case report.

Complete duplex ureter with ureterocele and multiple large ureteral stones is a rare congenital anomaly that can be easily misdiagnosed as bladder calculi. We report a 48-year-old woman who presented with urinary frequency and was preoperatively diagnosed with bladder stones. However, intraoperative ureteroscopy revealed a complete duplex ureter on the right side with a ureterocele in the lower segment harboring multiple large stones. A Y-shaped ureteral access sheath (UAS) was used as a working channel, enabling effective holmium laser lithotripsy and fragment evacuation. This case highlights the importance of considering ureteral anomalies in atypical stone presentations and suggests that modified UAS devices may facilitate safe and efficient treatment in complex anatomical settings.