Minimally Invasive Tract in Percutaneous Nephrolithotomy for Renal Stones

AIM: The aim of this study was to assess the efficacy, safety, and morbidity of minimally invasive tract in percutaneous nephrolithotomy (Mini-PCNL) for renal stones in comparison with the standard PCNL. PATIENTS AND METHODS: In a randomized trial, 69 patients (72 renal units) undergoing Mini-PCNL (group 1) from May 2004 to December 2007 were compared with a similar group of 111 (115 renal units) patients undergoing standard PCNL (group 2). Patients who needed more than one percutaneous tract or who had simultaneously undergone the two techniques on the same renal unit were excluded from the study group. Chi-square test was performed for statistical analysis of qualitative variables, and Student's t-test for quantitative variables. A p-value of <0.05 was considered significant. RESULTS: The two groups had comparable demographic data and some outcome of characteristics such as time of stay in hospital, postoperative pain, dose of postoperative analgesics, ratio of positive fever, and stone-free rates for some types of stones (e.g., staghorn stone and simple renal pelvis stone). The stone-free rate for multiple caliceal stones (85.2% vs. 70.0% in group 1 and group 2) was significantly higher in the Mini-PCNL group (p < 0.05). The incidence of bleeding necessitating transfusion (1.4% vs. 10.4% in group 1 and group 2) was significantly lower in the Mini-PCNL group (p < 0.05). In group 1, operative time for different stone types such as staghorn stone, simple renal pelvis stone, and multiple caliceal stones were 134.3 ± 19.7, 89.4 ± 21.5, and 113.9 ± 20.3 minutes, respectively, which were significantly longer than that for group 2 (118.9 ± 21.5, 77.0 ± 17.6, and 101.2 ± 19.1 minutes) (p < 0.05). CONCLUSION: Mini-PCNL is safe and effective for managing renal calculi in adult patients. Although smaller working sheath is associated with longer operative time, Mini-PCNL has significantly lower incidence of bleeding necessitating transfusion and higher stone-free rate for multiple caliceal stones in comparison with the standard PCNL.