Mini-Percutaneous Nephrolithotomy Outcomes in the Obese Population: A Retrospective Review.

Mini-percutaneous nephrolithotomy (PCNL) has gained popularity over the last decade due to its stone-free rate comparable to traditional PCNL but with decreased risk of complications. While the data on mini-PCNL has been favorable thus far, no study today has evaluated outcomes in obese patients. All patients undergoing mini-PCNL at our institution since we began its use in 2019 were included in this study. Mini-PCNL was defined as access sheath ≤22F in size. An obese group with body mass index (BMI) ≥30 was compared to a nonobese group with BMI <30. A patient was considered relatively stone free if residual fragments were <4 mm on follow-up CT with ≤3 mm cuts. Fisher exact test was used to compare dichotomous differences between variables, and -test to compare continuous variables. We identified 67 patients who underwent mini-PCNL during the study period with 33 patients in the obese group. Median BMI in the obese group was 36.4 kg/m compared to 25.05 kg/m in nonobese. There were no blood transfusions in either group during the study period. There was no statistical difference between the obese nonobese group for age, access sheath size, change in hemoglobin, same day discharge, percent relatively stone free, emergency department visit within 30 days, and median largest single stone diameter. There was a significant difference in the sum of all treated stone diameter in the obese group (median 15 mm) nonobese (median 18 mm,  = 0.02) (Table 1). Mini-PCNL appears to be equally safe and effective in obese and nonobese patients alike. While there was a statistically significantly higher amount of overall stone burden in the nonobese groups, the overall difference is not clinically significant. Further research is needed to validate our experience.