External validation of a model for tailoring the operative approach to minimally invasive partial nephrectomy.

Study type Therapy (case series). Level of evidence 4. What's known on the subject? and What does the study add? In comparison to open partial nephrectomy, renal hypothermia is not routinely performed when completed laparoscopically, making warm ischemia time (WIT) a critical issue. Given that the duration of renal ischemia is the strongest modifiable surgical risk factor for decreased renal function after partial nephrectomy, efforts to limit ischemic time are of paramount importance. One technical modification during laparoscopic partial nephrectomy (previously reported by Weizer et al.), sought to simplify the technique by obviating the need for hilar clamping and/or suturing based on preoperative tumour characteristics. Ideally this modification would allow the surgeon to significantly decrease or even eliminate WIT in selected cases without compromising oncological efficacy or adversely impact treatment outcomes. This study adds to the growing body of literature that seeks to minimize WIT during minimally-invasive partial nephrectomy (MIPN). We feel that this approach, which simplifies a technically challenging operation while maintaining a low rate of adverse events and positive surgical margins, could potentially have MIPN applied more broadly throughout the urological community and ultimately decrease the preference for radical nephrectomy in cases of T1a tumours. Objective To externally validate and modify an existing technical strategy of prospectively tailoring one's operative approach to minimally invasive partial nephrectomy (MIPN). Patients and methods We prospectively applied the model used in this strategy to evaluate 44 consecutive patients who underwent MIPN between August 2006 and August 2008. Patients were divided into four groups according to tumour depth of penetration or entry into the collecting system. Group 1 (n=9, 20%) underwent MIPN without clamping the renal hilum or parenchymal suturing. Group 2 (n=2, 5%) underwent clamping but not suturing. Group 3 (n=21, 48%) underwent clamping and suturing. Group 4 (n=12, 27%) underwent clamping, renal sinus reconstruction and suturing. We then assessed the peri- and postoperative outcomes, tumour histopathology and complications for each group. Results All patients had successful procedures according to the strategic model. The mean operative time was 246 (105-420) min and the mean estimated blood loss was 177 (25-1000) mL. When patients were stratified by clamping vs no clamping, the only significant variables between the two groups were operative time (245 vs 203 min) and pathology (83% vs 44% malignant). Six patients in the clamping group had postoperative complications (three had delayed bleeding, two had pneumonia, and one had infected urinoma) vs one patient in the no-clamping group who had prolonged ileus (P>0.05). Mean hospital stay was comparable in both groups (2.6 vs 3 days). Conclusion Minimally invasive partial nephrectomy can be tailored according to tumour location, avoiding unnecessary clamping and/or suturing of the kidney without negatively affecting treatment outcomes.