Ureteral Expanding Stent: A New Device for Urolithiasis

Abstract

We investigate a ureteral stent with radially expanding baskets producing passive dilation of the ureter for passage, capture, and removal of small ureteral stones. Polyurethane ureteral stents were slit to open 15 to 17 baskets along the length. The baskets are designed to dilate the ureter passively and capture stones <or=5 mm. Forty-two patients had these stents placed for stones at nine medical centers. Stone size ranged from 2 to 30 mm, while fragment size ranged from 1 to 8 mm. The locations of the stones ranged from the kidney to the lower ureter. The Ureteral Expanding Stent was inserted in the closed position, similar to a standard ureteral stent, and left in place for an average of 11 days. The device was inserted and extracted safely in all patients. Most patients experienced pain at an average rating of 3.7 of 10 on a visual analog scale. All stents were removed without significant morbidity. In 36 patients (86%), stones were removed with the stent (n=18) or passed while the stent was in place (n=18). The largest stone captured was 6 mm. The Ureteral Expanding Stent (OPEN-Pass) was used safely in 42 patients with stones. The device captured ureteral stones and facilitated stone passage around it. Stent retention or ureteral injury as a result of stone entrapment did not occur. The Ureteral Expanding Stent represents a new stone-removal and ureteral-dilation tool worthy of further clinical study.