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Sources of Funding: none

Introduction

Adhesive perinephric fat (APF) increases the complexity of robot-assisted partial nephrectomy (RAPN). The Mayo adhesive probability (MAP) score is an index for quantifying APF and predicting prolonged operation time or increased surgical complication rate. However, the part of the operation influenced by increased MAP score remains unclear.

Methods

The study subjects were 311 patients who underwent RAPN between January 2013 and June 2016 in our institute. MAP score was calculated to quantify APF. The perinephric fat thickness and stranding were used to calculate the MAP score. Operation time was divided into a dissection phase (from robotic manipulation to hilar clamping) and resection phase (from hilar clamping to robotic surgery completion).

Results

The patients’ mean age, body mass index (BMI), total operation time, console time, dissection phase time, and resection phase time were 60±13 years, 23.5±3.5 kg/m2, 180.8±40.7 minutes, 132.6±36.5 minutes, 84.9±27.6 minutes, and 47.6±18.3 minutes, respectively. The MAP score was 0 in 98 patients (32?), 1 in 86 (28?), 2 in 21 (7?), 3 in 48 (15?), 4 in 44 (14?), and 5 in 14 (4?). The dissection and resection phase times significantly increased as the MAP scores increased (Figure 1). The dissection phase times were 71.2, 79.1, 88.9, 97.0, 99.7, and 118.8 minutes as the MAP score increased by 1 point from 0 to 5 (p<0.001). The influence of MAP score was more remarkable to the prolongation of the dissection phase than to that of the resection phase. In the patients with MAP scores of ?3, the dissection phase time was not significantly influenced by the learning curve (100.8±25.2, 103.7±29.4, and 98.2±31.4 minutes in 1st–100th, 101st–200th, and 201st–311th, respectively). We further examined the factors that influenced the dissection phase time of 100 minutes by using the logistic regression model. In the multivariate analysis, left side, early surgical experience (first 100 cases), the number of the renal arteries to be clamped and MAP score (?3) were the independent factors of prolonged dissection phase.

Conclusions

MAP score is an independent predictive factor of prolonged RAPN dissection phase. The complexity of RAPN in the patients with high MAP scores was still high even for experienced surgeons.

Funding

none