Evaluation of the use of a biodegradable ureteral stent after retrograde endopyelotomy in a porcine model

Purpose: We evaluated the use of a poly-L-lactide-co-glycolide (PLGA) bioabsorbable ureteral stent after Acucise balloon incision (Applied Medical Resources, Rancho Santa Magarita, California) endopyelotomy in a porcine model. Materials and Methods: After unilateral Acucise endopyelotomy in 9 female Yucatan minipigs a self-reinforced PLGA stent was placed in 5 (group 1) and a 7Fr double pigtail Percuflex stent (Boston Scientific, Natick, Massachusetts) was placed in 4 (group 2). Preoperatively, and 6 and 12 weeks postoperatively plain x-ray of the kidneys, ureters and bladder, cystography, side specific creatinine clearance and retrograde ureterography were done. The contralateral ureters served as untreated controls. The 7Fr stents were removed at 6 weeks. All animals were sacrificed at 12 weeks after bilateral flow studies. Histological specimens from 4 sites along the urinary tract were graded on a healing score of O - normal, to 3 - severe changes. Results: Side specific creatinine clearance was similar to preoperative values at 6 and 12 weeks. At the 2 time points plain x-ray of the kidneys, ureters and bladder in group 1 showed retroperitoneal stent fragments in 3 of the 5 animals, which was confirmed at autopsy. Retrograde ureterography in group 1 showed mild hydronephrosis in all 5 ureters and saccular diverticula in 4, which was similar in 2 and 3 animals, respectively, in group 2. Cystography demonstrated grades 1 to 2 reflux in 2 animals at 6 weeks but none at 12 weeks in group 1 and no reflux at either time point in group 2. Flow rates and healing scores were statistically similar in the 2 groups but the latter trended toward less favorable healing of ureteral musculature with application of the absorbable stent. Conclusions: In this pilot study the use of self-reinforced PLGA biodegradable ureteral stents was feasible after Acucise endopyelotomy in a porcine model with radiographic and fluid flow results that were relatively similar to those of standard 7Fr stents but with less favorable biocompatibility.