An in vivo evaluation of a novel spiral cut flexible ureteral stent.

Objective: The flow characteristics, ureteral conformance, and histopathologic changes of a novel spiral cut flexible ureteral stent (Percuflex Helical, Boston Scientific, Boston, MA) were evaluated in vivo in an acute and chronic porcine model.

Materials And Methods: Flow characteristics and ureteral conformance of the novel stent were determined in 6 acute and 6 chronic swine models and compared with a control ureteral stent (Percuflex Plus, Boston Scientific). The flow characteristics were determined in vivo after ligating the renal vessels and via a nephrostomy tube delivering a standard rate of 0.9% saline at 35 cm H(2)O. Flows in the unobstructed ureter, normal stent, intraluminally obstructed stent, extraluminal obstructed stent, and both intraluminally and extraluminally obstructed conditions were determined. In the chronic animals, flow was determined at day 10, with the stent in place and immediately after stent removal. Conformance and hydronephrosis was assessed on pyelograms. Histopathologic changes were also evaluated in the chronic animals.

Results: The acute and chronic flow characteristics in the novel stent were equivalent to the control stent. Size and weight of the kidney, degree of hydronephrosis, stent migration, and presence of urinary tract infection were also similar between the test and control stents. There were no differences seen in histopathologic grading or degree of encrustation in either stent. The novel stent appeared to conform better to the shape of the ureter in both acute and chronic animals.

Conclusion: The novel helical stent appears to drain as well as a standard stent and causes no increased degree of histopathologic changes in the ureter.