title: New combined approach in metallic ureteral stenting to avoid urothelial hyperplasia: study in swine model.
abstract: OBJECTIVE
  We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure.
  
  
  METHODS
  We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 × 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation.
  
  
  RESULTS
  At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2.
  
  
  CONCLUSIONS
  Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.
authors.affiliation: Endoscopy Department, Minimally Invasive Surgery Centre Jesús Usón, Cáceres, Spain. fsoria@ccmijesususon.com
authors.forename: Federico
authors.initials: F
authors.lastname: Soria
authors.forename: Luis Ángel
authors.initials: LÁ
authors.lastname: Rioja
authors.forename: Esther
authors.initials: E
authors.lastname: Morcillo
authors.forename: Carolina
authors.initials: C
authors.lastname: Martin
authors.forename: Manuel
authors.initials: M
authors.lastname: Pamplona
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Sánchez
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005471:Fluoroscopy; D006965:Hyperplasia / Q000000981:diagnostic imaging / Q000517:prevention & control; D008670:Metals; D011897:Random Allocation; D018709:Statistics, Nonparametric; D015607:Stents; D034421:Sus scrofa; D014463:Ultrasonography; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging / Q000517:prevention & control*; D018666:Ureteroscopy
chemical_list: D008670:Metals