title: Hourglass-shaped nitinol prostatic stent in treatment of patients with lower urinary tract symptoms due to bladder outlet obstruction.
abstract: OBJECTIVE
  To assess the efficacy and safety of the thermoexpandable hourglass-shaped nitinol prostatic stent in the treatment of patients with lower urinary tract symptoms due to bladder outlet obstruction.
  
  
  METHODS
  The stents were inserted in an outpatient setting under local anesthesia and direct vision. Five different stent lengths (2.0 to 4.0 cm) were used, depending on the length of the prostatic urethra. Assessment of voiding function and symptom scores was performed at baseline, directly after stent insertion, at 14 days, and 1, 3, 6, and 12 months after stent placement.
  
  
  RESULTS
  We enrolled 35 men in the trial. In 5 patients, insertion of the stent failed, mainly because of anatomical limitations. After all placement procedures, minimal temporary hematuria was observed. Spontaneous voiding was achieved in all patients, with immediate significant improvements in voiding parameters and symptom scores. The median indwelling time of the stent was 70 days. Kaplan-Meier survival analysis showed that at 14 days and at 3, 6, and 12 months, the stent was still in situ in 73%, 40%, 33%, and 23% of the patients, respectively. The main reason for removal of the stent was migration (93%), in most cases toward the bladder. Removal was uneventful in all but 1 case.
  
  
  CONCLUSIONS
  The placement of the thermoexpandable hourglass-shaped nitinol stent results in relief of outflow obstruction and improvement of symptom scores. Because of the high migration rate, however, this stent design needs further improvement to be suitable for clinical practice.
authors.affiliation: Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. M.M.vanDijk@amc.uva.nl
authors.forename: Marleen M
authors.initials: MM
authors.lastname: van Dijk
authors.forename: Chaidir A
authors.initials: CA
authors.lastname: Mochtar
authors.forename: Hessel
authors.initials: H
authors.lastname: Wijkstra
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Laguna
authors.forename: Jean J M C H
authors.initials: JJ
authors.lastname: de la Rosette
mesh_terms: D000368:Aged; D000497:Alloys; D004867:Equipment Design; D006801:Humans; D008297:Male; D011446:Prospective Studies; D015607:Stents; D001748:Urinary Bladder Neck Obstruction / Q000150:complications / Q000601:surgery*; D014555:Urination Disorders / Q000209:etiology / Q000601:surgery
chemical_list: D000497:Alloys; C013616:nitinol