A randomized comparative study of flexible ureterorenoscopy versus mini-percutaneous nephrolithotomy for treatment of renal stones 2 cm or less

Background: Flexible ureterorenoscopy (fURS) and mini-percutaneous nephrolithotomy (mPCNL) have been increasingly used for the treatment of renal stones. However, current guidelines do not recommend one modality over the other. The aim of this study is to compare the safety and efficacy of treatment with fURS versus mPCNL for renal stones sized 2 cm or less. Materials and methods: A prospective, randomized, comparative study was conducted between January 2019 and July 2021 at 3 tertiary care urology centers. Inclusion criteria were adult patients with renal stone(s) <= 2 cm with inappropriateness or failure of extracorporeal shock-wave lithotripsy. Subjects were assigned to 1 of 2 treatment groups, either mPCNL or fURS. Two primary outcomes were assessed: (1) initial success rate, defined as the absence of clinically significant residual fragments (>2 mm) on kidney ureter bladder X-ray and ultrasound on the first postoperative day; and (2) complications, which were reported according to the Modified Clavien-Dindo classification system. Secondary outcomes included final success rate, defined as the absence of clinically significant residual fragments on noncontrast computed tomography on the 90th postoperative day; operative time; auxiliary procedures and blood transfusion rates; hemoglobin drop; and length of hospital stay. Results: One hundred and eighteen procedures were analyzed (59 in each group). The initial success rate of the mPCNL group (93%) was significantly higher than that of the fURS group (70%). Complications occurred more frequently with mPCNL than fURS (44.1% vs. 18.6%, respectively). Final success rate, operative time, and length of hospital stay were comparable between the 2 groups. Conclusions: Mini-percutaneous nephrolithotomy is more effective than fURS as a single-step treatment for renal stones <2 cm because of its higher initial success rate and lower auxiliary procedure rate. However, mPCNL results in significantly higher complication rates than fURS.