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 <25 kg/m(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 (<10, 10-20, >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.