ABSTRACT Objective To show the main indications of retroperitoneoscopy (RP) for the treatment of urolithiasis. The use of RP approach has been limited, being narrow working space the major issue to overcome (1), especially in non-expert hands. However, RP has the added advantages of no peritoneal contamination, a quick recovery of bowel function (2) and the possibility to use it in combination with other endourological techniques (3) and innovative technology. Materials and Methods We performed a retrospective analysis of 22 patients treated by the retroperitoneoscopic approach due to urolithiasis disease between 2015-2017. Type of surgery, stone free rate (SFR), complications according to Clavien-Dindo classification and mean hospital stay were recorded. Radical and partial nephrectomy cases were excluded for the SFR calculation. Descriptive statistical analysis was done using SPSS v21. Results Of the 22 patients treated by the retroperitoneoscopic approach, 9 underwent a ureterolithotomy, 4 underwent a nephrolithotomy, 8 were nephrectomies and 1 was a polar nephrectomy. In 3 cases we used the indocianine green fluorescence (ICG) to find avascular planes, reduce the bleeding, permitting enhanced visualization and reconstruction. In 3 cases an additional percutaneous approach was used, increasing the SFR chances. Eleven of thirteen (84.6%) patients were stone free following the procedure. Tree complications were recorded, two Clavien II and one Clavien III complications. Mean hospital stay was 4 days. Conclusions Retroperitoneoscopic approach is a good alternative for the treatment of large impacted ureteral stones, large pielic stones and for non-functional kidney removal due to stone disease. In expert hands, it can be safely used with a good SFR. The combination with ICG or other endourological techniques is feasible, allowing higher SFR.

ABSTRACT Objectives: To show our single-center experience in retroperitoneoscopic approach for highly complex posterior hilar tumors. Minimally invasive nephron sparing surgery for renal hilar tumors is extremely challenging due to their anatomic location, close to the main renal vessels and the collecting system (1). Transperitoneal approach is feasible, but highly complex because the anterior disposition of the vasculature. Retroperitoneal approach can easily provide access to the posterior hilar structures and the posterolateral surface of the kidney(2, 3). Materials and Methods: We retrospectively reviewed our hilar renal tumor database and analyzed those in which a retroperitoneoscopic approach was chosen. The RENAL score was then calculated, and operative and ischemia times were recorded. We also collected the mean hospital stay and the presence of complications. Pathology reports and follow-up were also gathered. Results: Five of our twelve highly complex hilar renal tumor patients were treated using a retroperitoneoscopic approach. Mean RENAL score was 10. Mean operative time was 135 minutes. Mean warm ischemia time was 14 minutes. Mean hospital stay was 4 days. We have recorded 2 complications. One patient required a transfusion and another presented with an urinary fistula which was treated by double J stent placement. The pathology report showed a clear cell renal cell carcinoma pT1a in most of the cases. Only one patient had a positive margin. To date, no recurrences have been noticed. Conclusions: The treatment of complex renal hilar tumors in a minimally invasive fashion is highly challenging even in experienced hands. Retroperitoneal partial nephrectomy is feasible, safe and effective for the treatment of such lesions. Long-term oncologic outcomes of this approach are awaited.