title: Skin to calyx distance is not a predictive factor for miniaturized percutaneous nephrolithotomy outcomes.
abstract: OBJECTIVE
  To evaluate the predictive value of the distance from skin to calyx (SCD) on the outcome and complication rates of patients undergoing mPNL.
  
  
  METHODS
  Patient's charts, who had undergone mPNL between June 2012 and June 2015, were analyzed retrospectively. Patients who had a preoperative computerized tomography (CT) were enrolled into the study. Two separateurologists evaluated the CT scans and calculated the SCD defined as the distance between the skin and surface/lateral edge of the calyx, which was the preferred site of entry for percutaneous access. The average value of the two measurements was included inthe final analysis to avoid bias. The mean SCD was 75mm. According to the median SCD value, patients were divided into two groups: group 1 (SCD ≤75) and group 2 (SCD >75).
  
  
  RESULTS
  A total of 140 patients and 130 patients were enrolled in groups 1 and 2, respectively. The mean operation time and the mean fluoroscopy time was significantly longer in group 2 (p:0.004 vs. p:0.021). The rate of blood transfusion was significantly higher in group 1 (6 patients). None of patientsin group 2required blood transfusion (p:0.017). Stone-free status after a single session of mPNL was 67.1% in group 1 and 75.4% in group 2 (p:0.112). After additional procedures, stone-free rates increased to 84.3% and 85.4% in group 1 and group 2, respectively (p:0.802).
  
  
  CONCLUSIONS
  Our study demonstrated that longer SCD was not a predictive factor for stone-free rates after mPNL. However, SCD over 75mm was associated with longer operation time and fluoroscopy time with lower rates of transfusion.
authors.affiliation: Department of Urology, Haseki Training and Research Hospital, Istanbul, Turkey.
authors.forename: Faruk
authors.initials: F
authors.lastname: Ozgor
authors.affiliation: Department of Urology, Haseki Training and Research Hospital, Istanbul, Turkey.
authors.forename: Onur
authors.initials: O
authors.lastname: Kucuktopcu
authors.affiliation: Department of Urology, Haseki Training and Research Hospital, Istanbul, Turkey.
authors.forename: Burak
authors.initials: B
authors.lastname: Ucpinar
authors.affiliation: Department of Urology, Haseki Training and Research Hospital, Istanbul, Turkey.
authors.forename: Fatih
authors.initials: F
authors.lastname: Yanaral
authors.affiliation: Department of Urology, Haseki Training and Research Hospital, Istanbul, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Binbay
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000000981:diagnostic imaging* / Q000601:surgery*; D007670:Kidney Calices / Q000000981:diagnostic imaging*; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects; D061646:Operative Time; D011379:Prognosis; D012189:Retrospective Studies; D012867:Skin / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: Kidney Calculi; Nephrostomy, Percutaneous; Obesity