title: Evaluation of the use of a biodegradable ureteral stent after retrograde endopyelotomy in a porcine model.
abstract: OBJECTIVE
  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.
  
  
  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 0-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.
authors.affiliation: Department of Surgery, Washington University School of Medicine, St. Louis, Missouri USA.
authors.forename: Ephrem O
authors.initials: EO
authors.lastname: Olweny
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
authors.forename: Cassio
authors.initials: C
authors.lastname: Andreoni
authors.forename: William
authors.initials: W
authors.lastname: Collyer
authors.forename: Kurt
authors.initials: K
authors.lastname: Kerbl
authors.forename: Mikhaila
authors.initials: M
authors.lastname: Onciu
authors.forename: Tero
authors.initials: T
authors.lastname: Välimaa
authors.forename: Ralph V
authors.initials: RV
authors.lastname: Clayman
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials; D005260:Female; D005355:Fibrosis; D019344:Lactic Acid; D008422:Materials Testing; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D015607:Stents; D013552:Swine; D014513:Ureter / Q000473:pathology; D014563:Urodynamics / Q000502:physiology
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid