title: Predictive factors for bleeding during percutaneous nephrolithotomy.
abstract: OBJECTIVE
  Although percutaneous nephrolithotomy (PCNL) has been accepted as a standard method for the management of large renal stones, the incidence of renal hemorrhage is relatively high. This study investigated the variables that affect bleeding during PCNL.
  
  
  METHODS
  The medical records of 370 patients who underwent PCNL by a single surgeon from January 2005 to December 2010 were reviewed retrospectively. All patients were divided into two groups according to median blood loss (lesser bleeding group and higher bleeding group). Various clinical and perioperative factors including age, sex, stone size and position, degree of hydronephrosis, operative time, underlying disease, history of anticoagulant medication, presence of previous nephrostomy catheter, stone composition, and thickness of the renal cortex were assessed. For statistical assessment, univariate and multivariate logistic regression analyses were used.
  
  
  RESULTS
  The mean patient age was 48.8 years (range, 22 to 75 years). Forty-three patients (11.6%) received a transfusion and 9 patients (2.4%) underwent angioembolization after surgery. The mean blood loss was 511.8±341.3 mL. Body mass index (BMI), stone size, stone position, operation time, and degree of preoperative hydronephrosis were predictive factors for severe bleeding during PCNL.
  
  
  CONCLUSIONS
  On the basis of the results achieved by a single surgeon, staghorn stones, high BMI, large stones, prolonged operation time, and absence of hydronephrosis were significantly associated with the risk of severe bleeding during PCNL.
authors.affiliation: Department of Urology, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Jeong Kuk
authors.initials: JK
authors.lastname: Lee
authors.forename: Bum Soo
authors.initials: BS
authors.lastname: Kim
authors.forename: Yoon Kyu
authors.initials: YK
authors.lastname: Park
keywords: Hemorrhage; Kidney calculi; Percutaneous nephrolithotomy