Tubeless mini-percutaneous nephrolithotomy for renal stones larger than 20 mm

The aim of this study is to evaluate the outcomes of tubeless mini- percutaneous nephrolithotomy (PCNL) for the treatment of large (>20 mm) renal stones.

This study included consecutive patients who underwent single-session tubeless mini-PCNL (tract size 16-20 F) for large (>20 mm) renal stones. Stone-free status meant complete clearance or residual fragments <4 mm. Complications were recorded and classified according to modified Clavien-Dindo classifications. Risk variables for significant residuals were determined with univariate (Chi-square and t-test) and multivariate logistic regression analyses.

Between July 2015 and November 2018, 225 patients were included. The mean age was 42.9 years; the mean stone size was 30.2 ± 9.6 mm and 75% of patients were males. A single renal stone was present in 54 patients (24%), multiple stones in 108 (48%), and staghorn stones in 63 (28%). The stone-free rate was 87.6%. The complication rate was 8.4% (Grade I-II in 7.5%, III in 0.9%). Three patients (1.3%) required blood transfusion. Independent risk factor for significant residual fragments was the presence of stones in multiple sites inside the pelvicalyceal system (relative risk: 13.44, 95% confidence interval: 1.78-101.43, P = 0.012).

Mini-PCNL is an effective and safe treatment option for patients with large renal stones (>20 mm). Stones located in multiple sites is the only predictor of significant residual stones.