LESS Partial Nephrectomy in a Porcine Model the needle drivers, the articulating needle drivers with their flexible characteristics did not provide sufficient strength during sutures, which made the sewing proce- dures more difficult. Therefore, replacing the flexible nee- dle drivers with rigid, conventional needle drivers became more convenient. When replacing the articulating needle driver with a rigid needle driver, the surgeons changed the right-hand instrument to the rigid needle driver, because all the surgeons in this study were right-handed. Also, we used right-angled forceps for the left-hand instrument and instead of using triangulation of the instruments we coor- dinated both instruments in a parallel position. During knot-tying, however, the instruments should be coordi- nated in a forward and backward direction, because there is no space for the instruments to move in a lateral direction as in pure laparoscopic surgery. 　During the renal parenchymal suturing, we used early unclamping and the sliding knot technique to shorten the ischemic time. Describing our early unclamping technique in detail, first, an interrupted renal parenchymal stitch was made. After making a loose square knot, we converted the square knot to a sliding knot. Then two or three more stitches were made according to the size of the paren- chymal resection. We made just one stitch fasten, un- clamped the bulldog clamp, and finally fastened the other stitches. This early unclamping technique resulted in the shortest warm ischemia time of 30 minutes. 　The limited warm ischemic time also makes LESS parti- al nephrectomy difficult. There are many controversies about warm ischemic time during partial nephrectomy. Shikanov et al reported in a multicenter study that ische- mic time (mean ischemic time was 29 minutes) does not af- fect global renal function in the case of two normal function- ing kidneys [7]. However, Becker et al reported in a mass analysis that in order to minimize parenchymal ischemic injury, the tumor should be removed within 20 minutes of warm ischemia, regardless of the surgical approach [8]. Large-scale institutions today score mean ischemic time around 30 minutes in the case of laparoscopic partial neph- rectomy and it is assumed that warm ischemic time under 30 minutes is required in order to successfully apply LESS to partial nephrectomy in clinical practice [9-11]. In our study, the mean warm ischemic time was 42 minutes. The experienced urologists group scored an average of 38.8 mi- nutes, and E2 achieved 30 minutes by using the early un- clamping technique. However, considering that this study was performed with a porcine model, a longer warm ische- mic time can be assumed in the case of a human kidney. Compared with the human body, the porcine model we used was smaller and had a smaller resected volume, which re- sults in a shorter distance and smaller defect to repair. Furthermore, it is believed that it is easier to obtain hemo- stasis in a porcine model than in a human kidney because of the different cell biology, blood supply, and tissue textures. All the above factors will make the procedure of LESS partial nephrectomy more difficult in humans than in the porcine model. Nguyen and Gill reported halving the 47 ischemic time from 31.1 to 13.9 minutes by using the early unclamping technique, although the technique was asso- ciated with a risk of bleeding and reclamping [12]. However, we can also infer that the early unclamping tech- nique and dry and wet laboratory disciplinary efforts to handle the instruments more freely can reduce the warm ischemic time. Although Hem-o-lok (Teleflex Medical, Research Triangle park, NC, USA) or surgical clips such as Lapra-Ty (Ethicon, Cincinnati, OH, USA) are generally used in laparoscopic partial nephrectomy, our study used only sliding knots for suturing. Proper use of surgical clips may enable further decreases in ischemic time. 　Another important fact that we found in this study was that there was no need for an additional trocar for LESS partial nephrectomy. All four surgeons could finish the LESS partial nephrectomy without any added trocars, even for right partial nephrectomies. 　Boylu et al reported 10 consecutive LESS partial neph- rectomies in porcine models performed by a single surgeon [5]. That study showed an overcoming of the learning curve with decreasing warm ischemic time. In our study, because of the limited number of cases and the many surgeons, the learning curve could not be assessed. But we can postulate that consecutive dry and wet laboratory discipline and ex- perience would improve surgical technique, shorten the warm ischemic time, and result in the surgeon overcoming the learning curve. CONCLUSIONS LESS partial nephrectomy was successfully performed in a porcine model without significant complications. How- ever, our study suggests that LESS for partial nephrectomy results in longer ischemic times than for conventional lapa- roscopic surgeries. Therefore, many dry and wet laboratory disciplinary efforts are needed to decrease the warm ische- mic time and improve this surgical technique. Conflicts of Interest The authors have nothing to disclose. REFERENCES 1. Clayman RV, Kavoussi LR, Soper NJ, Dierks SM, Meretyk S, Darcy MD, et al. Laparoscopic nephrectomy: initial case report. J Urol 1991;146:278-82. 2. 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