Predictors of Immediate Postoperative Outcome of Single-tract Percutaneous Nephrolithotomy

OBJECTIVE To evaluate the efficacy of single tract percutaneous nephrolithotomy (sPCNL) and investigate the preoperative predictive factors associated with stone clearance after sPCNL. METHODS A retrospective review of 351 cases of sPCNL performed at a single institution by 1 of 2 endourologists between January 2000 and March 2010 was performed. The primary outcome evaluated was stone-free rate (SFR) as assessed immediately after either an initial procedure or a second-look nephroscopy performed on postoperative day 2. Preoperative patient and stone factors, including age, sex, body mass index (BMI), preoperative hematocrit and creatinine, previous surgeries, comorbidities, renal anomalies, stone size, shape, location, and history of any previous treatment to the active stone burden were included in the univariate analysis. Significant or clinically relevant factors on univariate analysis were included in a logistic regression the multivariate analysis. RESULTS SFR after either an initial procedure or a second-look nephroscopy was 76%. On univariate analysis, rising preoperative creatinine, hypertension, increasing stone diameter, complete staghorn stone, presence of stones in the upper pole and absence of prior SWL were associated with lower SFR. Stone size, presence of stones in the upper pole, and prior SWL for the active burden were independent predictors of SFR on multivariate analysis. CONCLUSION sPCNL is an efficient procedure to clear renal stones, especially when used in conjunction with routine second-look nephroscopy. Increasing stone size and upper pole stones are associated with lower rates of stone clearance, whereas SWL performed before percutaneous nephrolithotomy (PCNL) is associated with improved stone clearance. The role of SWL before PCNL warrants further prospective investigation. UROLOGY 80: 19-26, 2012. (c) 2012 Elsevier Inc.