LESS Partial Nephrectomy in a Porcine Model actively practiced in clinical fields owing to its technical difficulties. 　We performed LESS partial nephrectomy in a porcine model with the objectives of overcoming the technical chal- lenges of LESS and exploring the feasibility of the proce- dure from a technical viewpoint. MATERIALS AND METHODS Under the approval of the Seoul National University Insti- tutional Animal Care and Use Committee (SNUIACUC), six partial nephrectomies were performed on bilateral kid- neys of a 5-month-old swine that weighed 30 kg. Three oper- ations were done on each kidney by a surgical staff consist- ing of two urologists with much experience in laparoscopic surgery (E1, E2) and two less-experienced urologists (B1, B2). A 5 mm flexible laparoscope was used for vision, and the choice of articulating needle driver, rigid needle driver, grasper, and dissectors was made according to the prefer- ence of each surgeon. 　While under general anesthesia, the swine was placed in a lateral flank position. After a 2.5 cm skin incision was made at the umbilicus, the subcutaneous fat tissues were dissected and the peritoneum was opened. The OctoportTM wound retractor (type B, designed for a small wound) was put into the peritoneal cavity covering from the skin to the peritoneum. The OctoportTM wound retractor has 3 access ports, one 12 mm port and two 5 mm ports, and also has an additional gas inlet and gas outlet (Fig. 1). After apply- ing the wound retractor, a 15 mmHg pneumoperitoneum was made with insufflation of CO2 gas. The renal hilum and Gerota's fascia were dissected to expose the renal capsule. After scoring around the imaginary tumor by use of monop- olar electrocautery, a bulldog clamp was applied on the re- nal artery and parenchymal resection was done. Bilateral renal hilar dissections were done by E1. E1 performed a partial nephrectomy on the anterior side of the right kidney upper pole, E2 on the anterior side of the right kidney lower 45 pole, and finally B1 on the posterior side of the right kidney lower pole, followed by B1’s right nephrectomy. The swine was then repositioned to the opposite decubitus position. After repositioning, E1 performed a partial nephrectomy on the anterior side of the left kidney upper pole, E2 on the anterior side of the left kidney lower pole hilar area, and last, B2 resected the left kidney after performing partial nephrectomy on the posterior side of the left kidney lower pole. All operators used 3-0 Vicryl running sutures to repair the open calyx and for hemostasis of the resection bed and 1-0 Vicryl interrupted sutures for renorrhaphy, which was done with sliding knots only, without the use of any suture slip equipment such as Hem-o-lok (Teleflex Medical, Re- search Triangle Park, NC, USA) or Lapra-ty (Ethicon, Somerville, NJ, USA). During the calyx and parenchyma FIG. 2. A typical example of partially resected renal parenchyma. FIG. 1. Porcine model under anesthesia with umbilical Octoport placement. FIG. 3. The resected right (A) and left (B) kidneys demonstrate perfect renal parenchymal sutures. Korean J Urol 2011;52:44-48