Objectives. Development of small animal models for laparoscopic surgery is important for basic pathophysiologic and oncologic studies, instrument development, and surgical training. Although transperitoneal laparoscopy has been described in the rat, the technical feasibility of the retroperitoneoscopic approach for major renal surgery has not been reported previously. Herein, we describe the development of a rat model for retroperitoneal minilaparoscopic nephrectomy.

Methods. Sixteen male Sprague-Dawley rats underwent a three-port bilateral retroperitoneoscopic nephrectomy using 2 and 3-mm instruments and optics exclusively. After developing the technique in 10 animals, the study was conducted in 6 animals. Following retroperitoneal balloon dilation and CO₂ pneumoretroperitoneum (mean 4.5 mm Hg), nephrectomy was accomplished by intracorporeal en bloc ligation of the renal pedicle. To prevent peritoneal entry, the anterior surface of the kidney was mobilized subcapsularly. Volume of the created retroperitoneal space and peritoneal integrity were confirmed by a contrast x-ray study. Intraperitoneal pressure was monitored constantly during the procedure.

Results. Mean surgical time was 74.5 minutes (range 60 to 95) and estimated blood loss was less than 1 mL. Mean volume of the retroperitoneal space was 8.4 mL after initial balloon dilation, and 11.5 mL after nephrectomy. Mean weight of the excised kidneys was 1.4 g. Inadvertent peritoneotomy occurred during 3 of 12 study nephrectomies. Complications included renal artery hemorrhage leading to death in 1 animal and renal vein injury in 1 animal.

Conclusions. Laparoscopic retroperitoneal nephrectomy in the rat model is technically feasible. This novel small animal model can be used for further studies of the retroperitoneal laparoscopic approach.