title: Long-Term Outcomes of Double-Layered Polytetrafluoroethylene Membrane-Covered Self-Expandable Segmental Metallic Stents (Uventa) in Patients with Chronic Ureteral Obstructions: Is It Really Safe?
abstract: To evaluate the long-term clinical efficacy and safety of double-layered polytetrafluoroethylene membrane-covered self-expandable segmental metallic stents (Uventa) in patients with chronic ureteral obstruction.
  
  
  
  In a retrospective study, a total of 50 ureter units (44 patients) with chronic obstructions were included from July 2010 to May 2015. Indications for Uventa placement were primary stenting for malignant ureteral obstruction, failed conventional polymeric Double-J stent (PS), or percutaneous nephrostomy (PCN) technique, with comorbidities or fears limiting PS/PCN changes, or with irritation or pain due to PS/PCN. Patients underwent Uventa stent placement using the antegrade or retrograde approach.
  
  
  
  There were no immediate procedure-related complications, and all stents were placed in the proper sites. During the median follow-up of 30.9 (interquartile range [IQR], 8.1-49.0) months, the primary (no obstruction and no additional intervention) and overall success (no obstruction and no additional intervention except supplementary Uventa) was 30.0% and 34.0%, respectively. Moreover, 14 of 50 ureter units (28.0%) experienced major complications (≥Clavien-Dindo class IIIb), such as ureteroarterial fistula (three cases, 6.0%), ureteroenteric fistula (three, 6.0%), ureterovaginal fistula (one, 2.0%), ureter perforation (one, 2.0%), uncontrollable bleeding (one, 2.0%), and complete obstruction (five, 10.0%). On univariate analysis, major complications were associated with female (odds ratio [OR] = 6.000), cervical cancer (OR = 4.667), ureteral stricture length (≥6.0 cm, OR = 4.583), and placement duration (≥24.0 months, OR = 20.429; all p < 0.05).
  
  
  
  In long-term follow-up, the Uventa stent demonstrated poor treatment outcomes with frequent major complications in patients with chronic ureteral obstructions.
authors.affiliation: Department of Urology, Asan Medical Center, University of Ulsan College of Medicine , Seoul, Republic of Korea.
authors.forename: Myong
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Urology, Asan Medical Center, University of Ulsan College of Medicine , Seoul, Republic of Korea.
authors.forename: Bumsik
authors.initials: B
authors.lastname: Hong
authors.affiliation: Department of Urology, Asan Medical Center, University of Ulsan College of Medicine , Seoul, Republic of Korea.
authors.forename: Hyung Keun
authors.initials: HK
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D020099:Coated Materials, Biocompatible; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008670:Metals / Q000009:adverse effects*; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000379:methods; D061214:Patient Safety; D011108:Polymers; D011138:Polytetrafluoroethylene; D011474:Prosthesis Design; D011860:Radiography, Abdominal; D012189:Retrospective Studies; D012307:Risk Factors; D015607:Stents / Q000009:adverse effects*; D016896:Treatment Outcome; D014513:Ureter; D014515:Ureteral Diseases / Q000150:complications; D014517:Ureteral Obstruction / Q000209:etiology* / Q000601:surgery*; D014548:Urinary Fistula / Q000150:complications; D002583:Uterine Cervical Neoplasms / Q000150:complications; D014624:Vaginal Fistula
chemical_list: D020099:Coated Materials, Biocompatible; D008670:Metals; D011108:Polymers; D011138:Polytetrafluoroethylene
keywords: complications; metallic stent; obstruction; treatment outcomes; ureteral stricture