Impact of weight on stone-free rate during percutaneous nephrolithotomy

Abstract

Background: To assess Impact of weight on stone-free rate during percutaneous nephrolithotomy. Methods: Hundred and twenty-three PNL procedures were done between January 2016 and July 2017. The patients were divided into four groups according to the World Health Organization (WHO) classification of body mass index (BMI): < 25 ((group 1, average)), 25–29.9 (group 2, overweight), 30–39.9 (group 3, obese), and ≥ 40 kg/m2 (group 4, morbidly obese). All groups were compared as regarding preoperative variables, intra-operative procedure and postoperative results. Results: The non-obese groups were younger in age than obese and morbid obese groups (P = 0.005). The difference in BMI was statistically significant between non-obese and obese groups (P = 0.0001). Most of females gender were obese and morbid obese (P = 0.0001) and most of the obese patients had left-sided renal stone (P = 0.001). Most of overweight and obese groups had radiopaque stones (P = 0.02). There were no statistically significant differences between all groups as regarding co-morbidity, stone size, stone locations, and hydronephrosis grade. Operative time (P = 0.034), length of hospital stay (P value = 0.014) and fluoroscopy time (P = 0.0001) were statistically significant differences between all groups. Number of accesses, access site, postoperative hemoglobin drop, post- operative complications, fate of residual stones and stone-free rate were not statistically significant differences between all groups. BMI was correlated with mean fluoroscopy time and mean hospitalization duration in our study as the time of hospitalization and time of x-ray exposure increase with obesity. Conclusion: PNL is a safe and effective procedure for obese patients. BMI do not predict clearance post PNL.