Comparative Outcomes of Mini Percutaneous Nephrolithotomy (Mini-PCNL) and Retrograde Intrarenal Surgery (RIRS) With Variable Laser Settings in the Management of 10-20 mm Lower Pole Renal Stones.

OBJECTIVE

The treatment of urolithiasis is changing with the development of new technological tools and laser technologies. In this study, we aimed to compare the operation types and laser lithotripsy settings used in 1-2 cm lower calyceal stones and the effect of these settings on success. Place & duration of study: Amasya University Faculty of Medicine, Şerefeddin Sabuncuoğlu Training and Research Hospital Department of Urology, Mustafa Kemal University Faculty of Medicine, between March 2019 and June 2021.

METHODS

A total of 263 patients who underwent retrograde intrarenal surgery (RIRS) (n = 155) and mini percutaneous nephrolithotomy (mPCNL) (n = 108) for the treatment of lower pole kidney stones between 2019 and 2021 were analyzed. Laser settings between 0.2-0.8 joules & 10-20 Hz were defined as high frequency using low-pulse energy (HiFr-LoPE), and settings between 1-2 joules & 5-10 Hz were defined as low frequency using high-pulse energy (LoFr-HiPE). The operation types according to laser settings were compared in terms of operative time, fluoroscopy duration, length of hospital stay, stone clearance rate, clinically insignificant residual fragment (CIRF), and complication rate.

RESULTS

The operation time and fluoroscopy time were significantly longer in the mPCNL group (p<0.001 and p<0.001, respectively). While the stone density was similar between groups (group 1 = 1039.00 (IQR = 930.00-1222.00) vs group 2 = 1101.00 (IQR = 900.00-1238.00); p = 0.406), the stone size was significantly higher in the mPCNL cohort (100.00 (IQR = 90.00 - 117.00) vs. 190.00 (IQR = 170.00-218.00), p<0.001). The stone-free rates (SFR) were similar between groups (p = 0.1011). Additionally, the required energy (J/mm) was higher in the mPCNL group (23.70 (IQR=21.41-25.92) and 25.21 (IQR=24.29-26.19) p<0.001). For further analysis, subgroup analysis based on stone size 1.5 cm was performed and showed that there is no significant difference in terms of total energy, required energy, and stone-free rate between groups in patients with stone size below 1.5 cm (p = 0.589, p = 0.210, and p = 0.845, respectively). However, operation time, total energy, and required energy were significantly higher in the mPCNL group in patients with stone size above 1.5 cm (p <0.001, p <0.001, and p <0.001, respectively). The most common low-grade (grade I and grade II) complications were seen (22 and 8, respectively), and the grade of complications was similar between groups (p = 0.233).

CONCLUSION

The laser technologies have added a significant contribution to urinary stone treatment. The required energy and laser time may provide crucial information for preoperative planning. The bigger stones require greater energy for fragmentation, and the percutaneous approach is advantageous when planning the treatment of this stones.