title: Does the use of ureteral stents with extraction strings increase urinary infection rates?
abstract: OBJECTIVE
  To assess the effect of ureteral stents with extraction string on the rate of postoperative UTI after ureteroscopies.
  
  
  METHODS
  Retrospective analysis of patient records who underwent ureteroscopy from January 2011 to August 2014 was performed. Patients were grouped into three groups according to postoperative stent status: non-stented or ureteral catheter for up to 24 h (NS), ureteral stent without extraction string (US) and ureteral stent with an extraction string (US-E).
  
  
  RESULTS
  There were 144, 133 and 282 cases in the NS, US and US-E groups, respectively. Overall infection rate was 4.7%; NS-2.1%, US-3.0% and US-E-6.7% (p = 0.057). Four percentage of men and 6.6% of women had postoperative UTI (p = 0.22). Within the group of men infection rates were 0, 2.4 and 6.4% for the NS, US and US-E groups, respectively (p = 0.01). For women, UTI rates were 7.5, 4.0 and 8.5% in the NS, US and US-E groups, respectively (p = 0.6). Infection rates were 20 and 3.9% (p = 0.001) for patients with extraction strings for >8 and <8 days. In multivariate analysis the presence of an extraction string was found to be a risk factor for infection OR 7.7 (1.01-58.9, 95% CI, p = 0.049) along with renal stone location OR 5.09 (2.1-12.05, 95% CI, p < 0.001).
  
  
  CONCLUSIONS
  No statistically significant difference was found between overall infections rates for patients with and without extraction strings, and such difference was found within the male group, suggesting extraction strings in men may increase the risk of infection.
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel. Yuvalfr@clalit.org.il.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Freifeld
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Demitry
authors.initials: D
authors.lastname: Goldin
authors.affiliation: The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: Luai
authors.initials: L
authors.lastname: Khalili
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Boris
authors.initials: B
authors.lastname: Friedman
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Leonid
authors.initials: L
authors.lastname: Boyarsky
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Klein
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Faris
authors.initials: F
authors.lastname: Gazy
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Stein
authors.affiliation: Department of Urology, Lady Davis Carmel Medical Center, Haifa, Israel.
authors.forename: Yoram
authors.initials: Y
authors.lastname: Dekel
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000453:epidemiology / Q000503:physiopathology; D011474:Prosthesis Design; D012189:Retrospective Studies; D018570:Risk Assessment; D015607:Stents / Q000009:adverse effects*; D014514:Ureteral Calculi / Q000175:diagnosis / Q000601:surgery*; D018666:Ureteroscopy / Q000009:adverse effects / Q000379:methods*; D014552:Urinary Tract Infections / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology
keywords: Stent; UTI; Ureteroscopy