title: Modified Clavien classification in percutaneous nephrolithotomy: assessment of complications in children.
abstract: OBJECTIVE
  Although percutaneous nephrolithotomy has been accepted as an effective minimally invasive procedure in children, there is still no consensus on how to define and stratify complications by severity.
  
  
  METHODS
  We retrospectively reviewed data of children who underwent percutaneous nephrolithotomy at our center between January 2002 and March 2010. A total of 100 procedures were performed in 94 patients with a mean age of 9.5 years. Complications were recorded according to modified Clavien classification.
  
  
  RESULTS
  Average stone burden ranged from 100 to 2,850 mm(2) (mean ± SD 507.5 ± 475). Stones were located in the renal pelvis in 32 kidneys, calices in 20, renal pelvis and calices in 31, and upper ureter in 3. Stone-free rate after a single session of percutaneous nephrolithotomy was 85%. After auxiliary procedures in 7 cases stone-free rate increased to 89%. Grade I complications were seen in 7 patients postoperatively, grade II in 19 (hematuria requiring blood transfusion in 13 and nonseptic infection requiring antibiotics in 6) and grade III in 4 (hydrohemothorax in 2 and urine leakage requiring Double-J® stent in 2). No grade IV or V complications were observed. Regression analysis showed that stone burden (OR 1.006, 95% CI 1.001-1.011; p = 0.03) and operative time (OR 1.044, 95% CI 1.011-1.077; p = 0.009) were independent risk factors for complications.
  
  
  CONCLUSIONS
  Percutaneous nephrolithotomy in children is safe, feasible and effective. Stone burden and operative time are independent risk factors for complications. The modified Clavien system provides a straightforward and validated method to classify postoperative complications.
authors.affiliation: Department of Urology, Ondokuz Mayis University Faculty of Medicine, Samsun, Turkey. eozden@omu.edu.tr
authors.forename: Ender
authors.initials: E
authors.lastname: Ozden
authors.forename: Mehmet N
authors.initials: MN
authors.lastname: Mercimek
authors.forename: Yarkın K
authors.initials: YK
authors.lastname: Yakupoǧlu
authors.forename: Ozan
authors.initials: O
authors.lastname: Ozkaya
authors.forename: Saban
authors.initials: S
authors.lastname: Sarikaya
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects*; D011183:Postoperative Complications / Q000145:classification / Q000209:etiology; D012189:Retrospective Studies; D012720:Severity of Illness Index