Pure retroperitoneal natural orifice translumenal endoscopic surgery (NOTES) transvaginal nephrectomy using standard laparoscopic instruments: a safety and feasibility study in a porcine model

In urology, retroperitoneal laparoscopy has become the preferred option for some surgeons because of its many advantages when compared to transperitoneal access. This approach avoids intestinal disturbance and injury, allowing for quick patient recovery and short hospital stays; postoperative adhesions are minimized for the above-mentioned reasons; retroperitoneal laparoscopy avoids the negative effects of previous abdominal surgery, and the risk of wound complications are also reduced [11‐13]. In addition, retroperitoneal anatomy is simpler than that of the abdominal cavity, and operative time is less than that required for the transperitoneal access [11‐14]. Based on these advantages, retroperitoneal laparoscopy is widely applied in urological procedures.

In recent years, minimally invasive surgery techniques are being developed due to similar diagnostic and therapeutic effect to open surgery with less operative trauma, reduced morbidity, shorter hospital stays, minimal scarring and lower cost. Using this new technique, surgeons can employ the natural orifices such as the vagina to enter the abdominal cavity to conduct operations. This technique completely eliminates the need for abdominal incisions, and decreases the wound complications. These potential benefits of NOTES are receiving increased attention [15].

In this study, we combine the transvaginal and retroperitoneal access routes to carry out pure NOTES nephrectomy in a porcine model using standard laparoscopic instruments and investigate the feasibility of this novel technique. The aim of the study was to explore a novel laparoscopic technique and determine its feasibility and safety.

Three cases were completely successful and survived after the procedures without any operative complications such as serious bleeding. One case was successful but required assistance of an extra laparoscopic port in the flank. The first two cases failed because of peritoneal rupture. It is well known that the peritoneal membrane is very thin, peritoneal rupture commonly occurred during the step of initial dissection. It was frustrating that we failed to repair the peritoneal membrane in the two cases due to narrow space and unclear visualization. Consequently, the CO2 gas would leak into the peritoneal cavity when we tried to enlarge and maintain retroperitoneal space for operation. Finally, we have no choice but to abort the first two cases. Fortunately, with increased experience, we prevented this issue successfully. We summarized that the deep inguinal ring and psoas muscle are important landmarks when dissecting the peritoneum. Finger dissection ought to touch the deep inguinal ring first, and maintains contacting with the psoas muscle to dissect. Subsequent peritoneal dissection was simple with the guidance of video endoscope.

Another key of the procedures was the placement of the access port. To facilitated the implantation of operative instruments and prevented gas leakage, we modified the conventional soft Triport to a hard Triport, Improvement of all these measures ensured the smooth implementation of the operation. Furthermore, the length of instruments also had an effect on the operation. In this study, we used extra-long instruments (45 cm). If this technique was applied to humans, longer laparoscopic instruments would be required.

Based on successful peritoneal dissection, placement of the access port, and clear anatomic landmarks, freeing and removal of the kidney was not difficult. In this study, we found that right side of nephrectomy was easier than the left because of the rectal interference. The whole procedure was performed without any intraoperative complications such as serious bleeding or injuries to organs. No postoperative complications were observed.

Even though our research has confirmed the safety and feasibility of transvaginal laparoscopic nephrectomy through retroperitoneal access preliminarily, we are yet unable to define the explicit intraoperative and postoperative complications, given that it is the first report of pure retroperitoneal NOTES transvaginal nephrectomy using standard laparoscopic instruments. The major complications of transperitoneal NOTES transvaginal access include the risk of pelvic infection, bowel perforation, transient brachial plexus injury, and dyspareunia vaginal cuff hematoma [16, 17]. We speculate that these two accesses have similar complications.

There are still some limitations in this new technique. First, this procedure can be used only in women. However, women’s view on this new technique is still inconsistent [18, 19]. Second, it is essential to design new instruments to perform the operation successfully. Although we are able to perform the operation smoothly in the porcine model, it would require considerable improvement of laparoscopic instruments before this new technique moving on to human trials.

Pure and hybrid transperitoneal NOTES transvaginal nephrectomy in human has been reported in recent years [20‐23]. Bazzi et al. successfully performed transvaginal hybrid NOTES partial nephrectomy in the porcine model by the SPIDER Surgical System [24]. The signification of retroperitoneal space through transvaginal access has also been identified in the literature [25]. Allemann et al. have performed transvaginal nephrectomy, adrenalectomy, and lymphadenectomy through retroperitoneal access in a porcine model and human cadaver in the recent years [26]. In their procedure, they completed the operation with one flexible endoscope and one laparoscopic instrument, but failed to retrieve the renal specimen due to the discrepancy between the size of the kidney and the width of the vaginal incision. Zorron et al. performed hybrid NOTES transvaginal retroperitoneoscopy to treat left renal cyst in one human case for the first time using a flexible two-channel colonoscope and two conventional laparoscopic instruments [9]. Robotic retroperitoneal NOTES transvaginal nephrectomy was also explored in a cadaver model [10]. Differing from these researchers, we performed the operation with the conventional laparoscopic technique and instruments (one 5 mm hard endoscope and two laparoscopic instruments), and removed the kidney through the transvaginal access. To our knowledge, we present the first report of pure NOTES transvaginal nephrectomy with conventional laparoscopic technique through a retroperitoneal access.