SMP vs RIRS for Symptomatic Lower Pole Renal Calculi of 10-20 mm Size: a Randomized Controlled Trial

Shock wave lithotripsy (SWL) is recommended for kidney stones \< 20 mm. However, the stone clearance of lower pole calculi after SWL is limited, thus leading to an extended indication for mini-percutaneous nephrolithotripsy (PCNL) even for stones between 10 and 20 mm in many centers. This trend is further promoted by introduction of super-mini PCNL (SMP), which is postulated to be less invasive compared to mini-PCNL due to the miniaturized instruments. However, this issue remains controversial. On the other hand, improvements in endoscopy technology have made retrograde stone removal more attractive. This has led to an increasing use of RIRS as a primary treatment although it is recommended only as 2nd-line option by current guidelines. However, the treatment of symptomatic lower pole calculi is a challenge for RIRS because of lower clearance rates. The purpose of this study is to evaluate the efficacy and safety of SMP and RIRS for the treatment for symptomatic lower pole calculi renal calculi measuring 10-20 mm.