title: Does the nephrostomy tract length impact the outcomes of percutaneous nephrolithotomy (PNL)?
abstract: OBJECTIVE
  Different factors can determine the outcomes of percutaneous nephrolithotomy (PNL). We analyzed the effect of tract length (TL) on outcomes after PNL.
  
  
  METHODS
  We performed a retrospective review of patients undergoing PNL between 2006 and 2011. Patients with preoperative computed tomography (CT), one percutaneous access tract and follow-up imaging within 3 months were included. TL was defined as distance between the skin to the calyx of puncture as measured on preoperative CT. Measurements were independently performed by two urologists and the average was used for analysis. Stone-free rate (SFR) was defined as zero fragments on follow-up imaging. Factors independently associated with the likelihood of being stone-free after PNL were determined using multivariable analysis adjusted for TL, location of access, the presence of incomplete or complete staghorn calculi and type of follow-up imaging. Complications (Clavien score) were independently assessed.
  
  
  RESULTS
  A total of 222 patients were included. Median stone burden and body mass index (BMI) was 239.4 mm(2) and 30.5 [interquartile range (IQR): 25.7-36.2]. The median TL was 85.0 mm (IQR: 70.3-100.0) and highly correlated with BMI (ρ = 0.66, p < 0.001). A total of 101 patients (45.5 %) were stone-free. TL was not associated with SFR (p = 0.53). Clavien 1 and 2 complications occurred in 38 (17 %) while Clavien 3 and 4 complications occurred in 17 (8 %) patients. Multivariable analysis revealed no association between complications and TL even when adjusted for gender.
  
  
  CONCLUSIONS
  Percutaneous TL is not associated with outcomes of PNL. PNL is a safe and effective treatment for stones in patients with differing body habitus.
authors.affiliation: Division of Urologic Surgery, Duke University Medical Center, DUMC 3167, Durham, NC, 27710, USA.
authors.forename: Gaston M
authors.initials: GM
authors.lastname: Astroza
authors.forename: Andreas
authors.initials: A
authors.lastname: Neisius
authors.forename: Matvey
authors.initials: M
authors.lastname: Tsivian
authors.forename: Agnes J
authors.initials: AJ
authors.lastname: Wang
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Preminger
authors.forename: Michael E
authors.initials: ME
authors.lastname: Lipkin
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous; D011677:Punctures; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome