Comparison of the Transperitoneal and Retroperitoneal Approach in Robot-Assisted Partial Nephrectomy in an Initial Case Series in Japan

Purpose: To compare the results from the transperitoneal and retroperitoneal approaches in our initial case series of robot-assisted partial nephrectomy (RAPN) in terms of surgical time, renal artery clamping time, postoperative renal function, adverse events, and surgical margin status. Patients and Methods: The initial 26 consecutive RAPNs performed for solid renal tumors in our hospital were categorized by the approach used, transperitoneal or retroperitoneal, and compared for body mass index, tumor size, R.E.N.A.L. nephrometry score, PADUA score, tumor location, surgical time, renal artery clamping time, renal function change after surgery, operative blood loss, surgical margin status, and adverse events (AEs). Results: The median tumor size was 25mm (range 15-50). A transperitoneal approach was used in 16 patients and a retroperitoneal approach was used in 10 patients. There was no significant difference in renal tumor and patient characteristics between the two groups except tumor location (anterior tumor was significantly more in the transperitoneal approach and posterior tumor was significantly more in retroperitoneal approach (P=0.0144 and P=0.0100, respectively)). Operative time (23963.0 minutes in the transperitoneal group vs. 193 +/- 40.6 minutes in the retroperitoneal group), warm ischemic time (24.3 +/- 9.07 minutes in the transperitoneal group vs. 24.7 +/- 8.35 minutes in the retroperitoneal group) and AEs (1/16 in the transperitoneal group vs. 1/10 in the retroperitoneal group; both cases were Clavien-Dindo grade I) did not show any significant difference between the two approaches (P=0.0792, 0.5485, and 0.7270, respectively). Conclusions: The retroperitoneal approach in RAPN appears to be a safe and technically feasible minimally invasive option for nephron-sparing surgery, based on our initial case series, and showed equivalent outcomes to those of the transperitoneal approach even though it was an initial robotic renal surgery series. Future studies, including a larger number of cases, are planned to draw more definitive conclusions.