Does Relocation of Lower Pole Stone During Retrograde Intrarenal Surgery Improve Stone-Free Rate? A Prospective Randomized Study.

Purpose: The aim of this study was to compare the stone-free rate (SFR) of in situ treatment vs relocation and lithotripsy for lower pole stones of less than 2 cm following retrograde intrarenal surgery (RIRS). Methods: This prospective randomized study was undertaken from June 2019 to May 2020 in patients undergoing RIRS for lower pole renal stones less than 2 cm in diameter. Patients were randomized into two groups: in situ lithotripsy group and relocation lithotripsy group. The in situ lithotripsy group underwent laser lithotripsy for lower pole stones without relocation of the calculus, and the relocation lithotripsy group had their stones relocated to a favorable location using a tipless Nitinol basket, followed by laser lithotripsy. Laser lithotripsy was achieved using the holmium:YAG (Ho:YAG) laser (120 W) with a 200-μm laser fiber. A Double-J stent was placed in all patients at the end of the procedure. Patient demographics, stone characteristics, operative outcomes, and complications were evaluated. The SFR was determined at 1 month postoperatively with a kidney, ureter, and bladder radiograph (KUB) and ultrasound KUB. Results: Sixty-eight patients were included in the study: in situ group ( n  = 35) and relocation group ( n  = 33). The mean stone size and stone density were similar between the groups. The total operative duration, lasing duration, and total energy used were similar between the groups. At the 1-month follow-up, the complete SFR was 85.7% and 91% in the in situ lithotripsy and relocation lithotripsy groups, respectively ( p  = 0.506). Conclusions: Relocation followed by subsequent laser lithotripsy was associated with similar SFRs as with in situ laser lithotripsy for lower pole renal calculi less than 2 cm in diameter following RIRS using the Ho:YAG laser.