Introduction: Flexible ureteroscopy (fURS) is an endoscopic procedure for the minimally invasive treatment of ureteral and renal calculi. Due to improvements in technique and ureteroscopic instrumentation over the past two decades, complications associated with URS are infrequent. However, in the event of an unexpected device malfunction or failure, the operating surgeon must employ prompt, resolute decision-making to resolve any intraoperative complications and avoid significant injury to the kidney or ureter. Case Presentation: The patient was a 53-year-old male with a 7 mm left upper pole renal stone managed by fURS and laser lithotripsy. A ureteral access sheath (UAS) was not deployed during the procedure. During fragmentation of the stone, we were unexpectedly unable to retract the ureteroscope from the ureter. Herein, we describe the procedural details leading up to the complication and the careful maneuvering required to remove the ureteroscope without damaging the ureter or the instrument. Conclusions: We recommend use of a UAS during fURS for the treatment of ureteral and renal calculi, if not using ureter access sheath, not advancing the ureteroscope above the stone, leaving it behind the tip of the instrument, while in the ureter. Utilization of a ureter access sheath could have possibly avoided this kind of complication.