Comparative study of the treatment of renal stones with flexible ureterorenoscopy in normal weight, obese, and morbidly obese patients

Objective To compare the efficacy and the safety of flexible ureterorenoscopy (f-URS) in the treatment of kidney stones according to the body mass index (BMI), which seems to be less influenced by weight compared with shock wave lithotripsy and percutaneous nephrolithotomy. Methods We conducted a retrospective monocentric study in patients with a known BMI who underwent an f-URS for kidney stones between 2006 and 2008. Success rates in the obese patients (OP) group (BMI ≥30 kg/m 2 ) were compared with success rates in the normal weight patients (NWP) control group (BMI 2 ). Patients with a BMI ≥40 kg/m 2 were defined as morbidly obese patients (MOP), a subgroup of the OP group. The success was defined as a stone-free status (no or ≤2 mm residual stone) at the time of control, 3 months after the procedure assessed by kidneys-ureters-bladder radiography coupled with ultrasound (only in NWP with radiopaque stones), or computed tomography-scan. Results A total of 327 procedures were performed, including 97 f-URS in 87 OP (including 14 procedures in 13 MOP) and 230 procedures for 188 NWP. The overall success rate was 67.4% and 68% in the NWP and OP, respectively; P = .91 (71.4% in the MOP subgroup). Success rates decreased with an increasing stone size without any differences between the groups. Regardless of location and stone size ( 20 mm), there was no statistical difference in the success rate. Postoperative morbidity was similar in both groups and occurred in 2.44% of cases. Conclusion f-URS for kidney stones resulted in similar outcomes in NWP and OP, and even MOP, regardless of stone size and location and with equivalent morbidity.