Prospective Evaluation of Preoperative Factors to Predict Intraoperative Difficulty during Transperitoneal Laparoscopic Simple Nephrectomy for Non-functioning Kidney Secondary to Urolithiasis

Background: Laparoscopic simple nephrectomy (LSN) for non-functioning kidney (NFK) due to urolithiasis is considered difficult with higher conversions to open surgery and complication rates than radical nephrectomy. Preoperative assessment of operative difficulty would be useful for optimal preoperative planning, to select patients with less difficulty in early phases of learning and to counsel patients. There is a paucity of the prospective studies assessing intraoperative difficulty during LSN for stone related NFK.

Objectives: To evaluate preoperative clinical and radiological characteristics that could predict difficulty during transperitoneal LSN for NFK due to urolithiasis.

Methods: A prospective study was done in National Academy of Medical Sciences, Bir Hospital, Kathmandu, Nepal from September 2021 to August 2022 among patients undergoing transperitoneal LSN for NFK secondary to urolithiasis. Demographic and clinico-radiological parameters were documented preoperatively. A single experienced surgeon provided the difficulty score for major steps of surgery in a Likert scale of 1(easy) to 4 (most difficult). Final difficulty scale was calculated adding blood loss and operative duration as surrogate markers of difficulty. Patients were divided into two groups, Easy group, and Difficult group based on difficulty scale. Preoperative, intraoperative, and postoperative characteristics were compared between the groups. Univariate and multivariate analysis was done to identify factors that could predict intraoperative difficulty.

Results: There were 88 patients included in the final analysis. Presence of pyonephrosis (p<0.001) and preoperative percutaneous nephrostomy (p=0.04) showed significant correlation with intraoperative difficulty in univariate analysis. However, pyonephrosis was only significantly associated with difficulty during multivariate analysis (OR 3.87, 95% CI 1.00-14.96). Patients with pyonephrosis had higher conversion rates to open surgery and higher complication rates.

Conclusions: Pyonephrosis in NFK secondary to urolithiasis predicted higher intraoperative difficulty during LSN. Patients with pyonephrosis experienced higher conversions to open surgery and higher complications rate.