A Comparative Study on Outcomes of Retrograde Intrarenal Surgery (RIRS), Mini Percutaneous Nephrolithotomy (PCNL), and Extracorporeal Shock Wave Lithotripsy (ESWL) for Lower Pole Renal Calculi of < 1.5 cm

Background: Percutaneous nephrolithotomy (PCNL), established in the 1970s, has replaced open surgery for large stones. Extracorporeal shock wave lithotripsy (ESWL), once the preferred first-line treatment for small-to-medium-sized renal stones, has a questionable charm owing to patient reluctance for repeated treatments and hospitalizations since ESWL has a reduced stone-free rate (SFR). Flexible ureterorenoscopy, also referred to as RIRS, originally applied in the management of lower pole stones resistant to ESWL, is increasingly being used as a primary modality to manage lower pole stones, and it may potentially achieve higher SFR than ESWL and lower morbidity than PCNL for patients with low-volume stone diseases. Objectives: Observations were made to compare ESWL, mini PCNL, and RIRS in managing lower pole renal calculi of < 1.5 cm. Methods: This observational study encompassed all patients with lower pole renal stones with < 1.5 cm diameter and < 1000 HU density who underwent mini PCNL, RIRS, or ESWL from January 2020 to July 2021. There were 40, 60, and 60 patients in the RIRS, mini PCNL, and ESWL groups, respectively, for all of whom preoperative CT urogram was performed. The patients were informed of the procedures, and their informed consent was obtained. The stone-free rates of the three modalities were compared, and the outcomes were statistically analyzed. Results: The mean stone sizes in the present study were 12.99 × 3.56 mm in mini PCNL, 10.62 × 2.51 mm in RIRS, and 10.93 × 3.13 mm in ESWL. The mini PCNL group's SFR was significantly higher than those of other groups: 59 (98.3%) in mini PCNL, 34 (85%) in RIRS, and 46 (76.7%) in ESWL (P = 0.002). Out of the 60 patients in the mini PCNL group, only one (1.7%) required an ancillary procedure, while only six (10%) out of 40 patients in the RIRS group and 11 (18.33%) out of 60 patients in the ESWL group required the ancillary procedure (P = 0.031). Conclusions: For lower pole renal calculi < 1.5 cm, mini PCNL has the highest SFR, followed by RIRS and ESWL, in sequence. The ancillary procedure rate was 18.33% in the ESWL group, which was higher than those of mini PCNL (1.7%) and RIRS (10%).