Drainage and antireflux characteristics of a biodegradable self-reinforced, self-expanding X-ray-positive poly-L,D-lactide spiral partial ureteral stent: an experimental study.

Objective: To evaluate the drainage and antireflux characteristics of a new self-expandable self-reinforced poly-L,D-lactide partial ureteral stent (SR-PLA 96) in an experimental model.

Methods: Twelve dogs were used as experimental animals. A low-midline laparotomy and cystotomy were performed on all animals. In group A (six animals), 50-mm long SR-PLA 96 ureteral stents with a double-helical spiral design were inserted into both ureters, leaving the lower ends 2 cm above the ureterovesical junction. In group B (six animals), both ureters were stented with traditional pigtail stents (C-Flex) Double-J; Cook Urological), which were removed 8 weeks after surgery. Renal function and ureteral patency were evaluated by dynamic kidney imaging and urography examinations at 6 and 12 weeks postoperatively. The degrees of vesicoureteral reflux at two levels of the ureters and at the level of the renal pelvis were evaluated by nuclear voiding cystograms at 6 weeks.

Results: The partial SR-PLA 96 stent design showed more favorable antireflux properties that the Double-J stent design. The degree of vesicoureteral reflux, reflected in an increase of nuclear enhancement at 6 weeks, was lower in the distal (7.9% +/- 14.7% v 63.2% +/- 17.3%; P < 0.05) and middle (6.1% +/- 8.1% v. 45.5% +/- 19.5%; P = 0.15) levels of the ureters as well as at the level of the renal pelvis (-3.4% +/- 3.6% v 6.2% +/- 3.9%; P = 0.65) than in the Double-J-stented ureters. No significant differences in renal function or ureteral patency were observed at 12 weeks after the Double-J stents had been removed and the SR-PLA 96 stents had fragmented.

Conclusions: A self-expandable, self-reinforced SR-PLA 96 partial ureteral stent showed more favorable antireflux properties than a Double-J stent.