title: Severely encrusted polyurethane ureteral stents: management and analysis of potential risk factors.
abstract: OBJECTIVE
  To review the management of heavily encrusted and stuck JJ ureteral stents. We report our experience and review current published reports in managing heavily encrusted and stuck JJ stents, the guidelines for management, and the prevention of such problems.
  
  
  METHODS
  We reviewed our stent records from January 1994 to December 2000 and analyzed our stent complications and their final outcome. Fifteen patients had heavily encrusted and stuck stents. Of these, 14 were encountered in patients with a sizable stone burden (400 to 650 mm(2)) and 1 occurred in a patient with malignant ureteral obstruction. Sandwich combinations of multiple extracorporeal shock wave lithotripsy/traction and endourologic procedures were used to render them stone and stent free. The stent was examined and the encrustation was analyzed by x-ray crystallography.
  
  
  RESULTS
  Of 15 patients, 13 were available for evaluations; 1 patient was lost to follow-up and 1 patient died. The average stone burden was 625 mm(2). The encrustation was localized to the upper end in eight and to the lower and upper end in three. In 4 cases, the entire stent was encrusted, and the lumen was occluded in 12. All 13 patients with stuck, fragmented, and encrusted stents were rendered stone and stent free; 2 of the 13 had clinically insignificant residual stones (less than 2 mm). Calcium phosphate and monohydrate stones were the most commonly encountered stone encrustations.
  
  
  CONCLUSIONS
  Stent encrustation is one of the most serious complications of polyurethane JJ stents. Multimodal endourology should form the cornerstone of therapy for heavily encrusted stuck stents. It is important to maintain an efficient computerized stent log under the direct supervision of a physician. Patients with probable risk factors should be monitored even more frequently to avoid mishaps and morbidity.
authors.affiliation: Department of Urology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: I
authors.initials: I
authors.lastname: Singh
authors.forename: N P
authors.initials: NP
authors.lastname: Gupta
authors.forename: A K
authors.initials: AK
authors.lastname: Hemal
authors.forename: M
authors.initials: M
authors.lastname: Aron
authors.forename: A
authors.initials: A
authors.lastname: Seth
authors.forename: P N
authors.initials: PN
authors.lastname: Dogra
mesh_terms: D000328:Adult; D001672:Biocompatible Materials; D005500:Follow-Up Studies; D005547:Foreign Bodies / Q000209:etiology / Q000601:surgery; D006801:Humans; D008096:Lithotripsy; D008297:Male; D009403:Nephrostomy, Percutaneous; D011140:Polyurethanes; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D015607:Stents / Q000009:adverse effects*; D016896:Treatment Outcome; D014513:Ureter / Q000601:surgery; D014514:Ureteral Calculi / Q000209:etiology* / Q000628:therapy*; D014517:Ureteral Obstruction / Q000209:etiology* / Q000628:therapy*; D018666:Ureteroscopy
chemical_list: D001672:Biocompatible Materials; D011140:Polyurethanes