A 7.5/8.2 F actively deflectable, flexible ureteroscope: a new device for both diagnostic and therapeutic upper urinary tract endoscopy.

OBJECTIVE: To develop and employ in a prospective fashion a small-diameter, actively deflectable, flexible ureteroscope that could be easily placed into the upper urinary tract and would increase the overall therapeutic potential for this class of endoscope.

METHODS: A small-diameter, actively deflectable flexible ureteroscope was recently employed in clinical trials at two university centers. Improvements in fiberoptic engineering allowed endoscope miniaturization (7.5 F tip and 8.2 F shaft) while maintaining a relatively large (3.6 F) centrally located working channel. A variety of design modifications were employed through various prototype stages. Mechanical parameters included maximizing two-way active deflection, adequate secondary deflection allowing access to the lower pole caliceal system, and maintaining a sturdy (nonbuckling) durometer.

RESULTS: The 7.5 F flexible ureteroscope was employed in sixty-seven procedures (64 patients). Therapeutic rather than purely diagnostic maneuvers made up the majority of procedures. Thirty-one upper ureteral, renal pelvic, or caliceal calculi were treated with a variety of endoscopic lithotriptors placed through the ureteroscope. Six patients underwent both biopsy and endoscopic treatment of superficial papillary transitional cell malignancies. Retrograde endopyelotomy, incision or dilation of ureteral strictures, extraction of renal pelvic foreign bodies, and endoscopic access and treatment of obstructed caliceal diverticula were other applications. Endoscopic access to the upper urinary tract rarely required active intramural ureteral dilation (14%). Excluding patients with prior ureteral stents or those who underwent rigid distal third ureteral endoscopy prior to flexible proximal ureteroscopy, 31 patients (48%) required no intramural ureteral dilation prior to placing the endoscope.

CONCLUSIONS: The increased therapeutic potential observed with the 7.5 F actively deflectable, flexible ureteroscope opens a variety of upper urinary tract pathologic states to minimally invasive (endoscopic) treatments.