Natural orifice translumenal endoscopic surgery (NOTES) renal cryoablation in a porcine model


Jihad H. Kaouk, Director, Section of Robotic Surgery, Cleveland Clinic, A-100 9500 Euclid Avenue, Cleveland, OH 44195, USA.



To present our laboratory experience with natural orifice translumenal endoscopic surgery (NOTES) renal cryoablation.


In two female farm pigs, we performed four procedures of NOTES renal cryoablation. In each pig, NOTES was performed through a transgastric approach and a transvaginal approach for each kidney, respectively. The pig was placed in the flank position and pneumoperitoneum obtained using a transabdominal Veress needle. In the first pig, we started with the left kidney with a transgastric approach: a dual-channel video gastroscope (Olympus, Tokyo, Japan) was used, the stomach wall was punctured using a needle-knife, a guidewire was passed into the abdominal cavity and the access dilated using a controlled radial expansion balloon. The bowel was mobilized medially and the Gerota’s fascia overlying the upper pole was dissected. Under direct endoscopic vision, a cryoablation probe was introduced percutaneously into the anterior upper pole of the kidney. The pig was then flipped to the right flank position and a transvaginal approach was used: the gastroscope was introduced through the posterior fornix of the vagina. For the second pig, we performed initially a transgastric right-side cryoablation then a transvaginal left-side cryoablation as described for the first pig.


All four procedures were performed successfully, with no intraoperative complications. No additional laparoscopic ports or open conversions were necessary. The vision of the kidney and the ice-ball was adequate for all cases. The mean operative duration was 83 min. Stomach closure was tested watertight, and there were no abdominal or pelvic injuries found at autopsy.


NOTES can provide adequate minimal surgical dissection for safe and effective percutaneous renal cryoablation under direct videoscopic monitoring at kidney locations otherwise not accessible percutaneously. Both transgastric and transvaginal approaches can be used effectively for renal cryoablation providing a minimally invasive scar-less surgery.


Renal cryoablation for small localized kidney tumours is gaining momentum especially for patients with increased surgical risk. Renal cryoablation has been performed using the laparoscopic approach with excellent intermediate outcomes [1]. Although most posterior and lateral kidney tumours are accessible percutaneously, anteriorly located tumours necessitate a transperitoneal approach using three to four laparoscopic ports. Advantages of the laparoscopic approach include mobilization of vital structures, such as bowel, away from the treatment area and careful visual monitoring of cryoprobe placement and ice-ball progression in relation to the kidney mass.

In an effort to further minimize surgical morbidity, single-port laparoscopic renal cryoablation has been reported clinically. This technique eliminates the need for multiple port-site incisions and provides a single laparoscopic entry site hidden in the umbilicus [2].

Natural orifice translumenal endoscopic surgery (NOTES) is an emerging technique with significant experimental and clinical ongoing investigation. NOTES may further reduce the morbidity and provide a scar-less surgery [3]. Transgastric and transvaginal approaches have been used to access the peritoneal cavity [4–7].

Herein we present our experience with transgastric and transvaginal NOTES renal cryoablation in a porcine model, as an alternative to the laparoscopic approach, for anteriorly located renal tumours not accessible percutaneously.


The study protocol was approved by our Institutional Animal Care and Use Committee and comprised two female farm pigs, weighing 38 and 41 kg. Both pigs underwent NOTES cryoablation of the upper pole anterior aspect of both kidneys. In the first pig we performed a transgastric approach for left kidney cryoablation and a transvaginal approach for a right kidney cryoablation. In the second pig we used a transgastric approach for right kidney cryoablation and a transvaginal approach for a left kidney cryoablation . Thus, four cryoablations were completed (two right and two left), using transgastric (two) and transvaginal (two) approaches.

We used a dual-channel video gastroscope GIF-2T160, 1350 mm with an outer diameter of 13.2 mm and instrument channels diameter of 2.8 and 3.7 mm (Olympus America Corp, Melville, NY, USA). The endoscopic instruments used included a grasper, scissor, needle-knife, and 15 mm radial expansion dilating balloon (Figs 1,2). T-fastener 0 polypropylene (Davol Inc., Cranston, Rhode Island, USA) were used to close the gastric incision. For cryoablation, we used a 2.4-mm cryoablation probe PERC-24, R2.4 (Endocare, Irvine, CA, USA).

Figure 1.

Image of the videogastroscope used. Note the two light sources, two working channels and optics.

Figure 2.

Image of endoscopic scissors and monopolar grasper inserted through each of the gastroscope working channels.


Following general endotracheal anaesthesia, the pigs were placed in the lateral flank position. The pneumoperitoneum was obtained using a transabdominal Veress® needle. After the first procedure, the pig was turned to perform the contralateral procedure on the opposite kidney.

Transgastric access

The videogastroscope was inserted per orally into the stomach. The site of transgastric access was identified on the inner stomach wall and then two 0 polypropylene T-fasteners were deployed into the stomach wall 1 cm apart. Using a needle-knife inserted through the gastroscope channel, a small gastrotomy was made and a guidewire was passed into the peritoneal cavity (Fig. 3). The opening was enlarged using a 15-mm controlled radial expansion dilating balloon inflated to maximum capacity then the double-channel gastroscope was pushed into the peritoneal cavity. The gastrotomy site was evaluated easily with a retroflexion direction of the gastroscope. The dilating balloon and the guidewire were removed and a grasper with monopolar cautery and scissors were inserted into each of the gastroscope working channels, respectively.

Figure 3.

Endoscopic vision through the gastroscope. Note the deployed T-fastener in the inner stomach wall and the adjacent endoscopic needle-knife used to incise the stomach wall.

Intraperitoneal dissection was started by mobilizing the colon medially by incising the Toldt fascia. Pneumoperitoneum pressure helped maintain the dissected plan with excellent visualization. Gerota’s fascia was then exposed and dissection was carried out from the middle to the upper pole of the kidney from within the Gerota’s fascia and adequate exposure of the anterior aspect of the upper pole of the kidney is achieved. Under direct endoscopic vision, a cryoprobe was advanced percutaneously into the marked upper kidney pole. Cryoablation was completed as described below under direct gastroscopic visualization of the forming ice ball.

After cryoablation, pneumoperitoneum was released and the gastroscope was pulled back into the stomach. The previously deployed T-fasteners were secured and locked into place to close the gastrotomy site (Fig. 4).

Figure 4.

Endoscopic vision during gastric closure using the two pre-deployed T-fasteners.

Transvaginal access

The posterior fornix of the vagina was opened with the needle-knife (Fig. 5) and a wire guide was introduced into the intraperitoneal space, then the vaginal incision dilated with a 15-mm controlled radial expansion dilating balloon (Fig. 6) and the gastroscope pushed into the peritoneal cavity. The pelvis and the vaginal entry point were explored by retroflexion of the gastroscope. The dissection was made as describe for the transgastric access. The gastroscope was positioned above the kidney and retroflexed to have a superior view of the kidney. This retroflexion also provided a good exposure of the kidney by pushing the liver or the spleen away from the cryoablation site. After completion of kidney upper pole cryoablation, the gastroscope was removed without closure of the vagina.

Figure 5.

Endoscopic vision when gaining transvaginal access through the posterior vaginal fornix.

Figure 6.

Endoscopic vision showing the dilatation of the vaginal incision with a controlled radial expansion balloon.


After gaining intraperitoneal access and complete dissection of the kidney upper pole as described above, the Veress® needle was removed and replaced by a 2.4-mm Cryoprobe inserted at the same skin puncture site of the Veress needle (Fig. 7). Pneumoperitoneum was maintained by continuous insufflation through the gastroscope. The Cryoprobe was inserted under direct gastroscopic vision into the marked site of the kidney anterior upper pole (Fig. 8). Two freezing cycles were performed and the ice ball formation and advancement was monitored gastroscopically (Fig. 9). The first freezing cycle was done for 10 min and the second cycle for 8 min. After passive thawing, the cryoprobe was removed under vision and the kidney was observed for any bleeding.

Figure 7.

Intraoperative photograph showing the flank positioning of the pig with the cryoprobe inserted percutaneously and the endoscope inserted transvaginally.

Figure 8.

Endoscopic vision showing excellent view of the kidney with retroflexion of the endoscope. Note the cryoprobe inserted in the anterior upper pole of the kidney.

Figure 9.

Endoscopic vision during the first freezing cycle. Note the position of the renal hilum and the kidney upper pole.

Upon completion of cryoablation procedure, the pig was killed. An autopsy was performed and bilateral lumbar regions, stomach, upper quadrant of the abdomen and the pelvis were examined for any injuries. Gastric entry-site closure was tested by filling the stomach with saline solution and checking for any leakage. Kidneys were examined ex vivo for any vascular injury or lacerations.


All procedures were performed successfully without any addition of laparoscopic ports. The only visible scare was the site of percutaneous insertion of the Veress needle and cryoprobe. No complications occurred during any procedure and surgical access and exposure of the anterior upper kidney pole was adequate with enough space dissected around the kidney to avoid accidental freezing of surrounding organs. The mean (range) total operative duration was 83 (76–94) min. The operative duration was longer for the transgastric approach vs the transvaginal approach, at a mean (sd) of 91 (4.2) min vs 74.5 (2.1) min. Gastric closure was watertight in both cases. The cryoablation time was the same for all procedures (10 min and 8 min for the first and second cryoablation cycles, respectively). The mean (range) cryoablation zone diameter was 3.7 (3.5–3.9) cm. Blood loss was <20 mL in all cases. There were no inadvertent injuries to kidney or surrounding bowel or other organs during dissection or during the freezing cycles (Table 1).

Table 1. 
Intraoperative data
Mean (range):  
 operative duration, min91 (88–94)74.5 (73–76)
 access time, min10.5 (10–11) 6.5 (6–7)
 freezing time, min1818
 closing time, min16.5 (15–18) 0
 complications, n 0 0
 cryoablation size, cm 3.7 (3.5–3.8) 3.8 (3.6–3.9)


NOTES represent the next step in minimally invasive surgery after laparoscopy. It may help further reduce the invasiveness of standard laparoscopic and robotic techniques accepted today. Such surgery performed through a natural orifice, will potentially have better recovery and less postoperative complications such as hernias [3,6].

Cryoablation has the largest clinical body of evidence with the longest follow-up and the most reported studies [8]. Advantages of cryoablation include excellent ice-ball monitoring to control complete tumour coverage with adequate tissue margin. Percutaneous cryoabalation provides a minimally invasive approach; however, it is limited by inability to separate vital structures away from the targeted tumour when needed and is associated with significant radiation exposure when performed under CT guidance.

The combination of NOTES and percutaneous cryoablation combine the advantages of both techniques and allow adequate accessibility to anterior tumours otherwise not accessible percutaneously. Endoscopic visualization was adequate for all procedures. When necessary, the optic was washed with saline solution injected through the gastroscope in situ without removing the gastroscope.

Limitations of our approach were mainly a lack of suitable instrumentation to use through the gastroscope and surgeon’s training to navigate flexible endoscopic instruments. Retraction with the gastroscope was also limited. In the pig model, the vagina was not closed because of the technical difficulties due to the pig’s specific anatomy with a narrow and long vagina. However, vaginal closure can be done effectively in humans [9].

NOTES cryoablation may provide a minimally invasive and scar-less treatment of small localized renal tumours. A specific NOTES cryoprobe that can be inserted through the gastroscope working channel or alongside the gastroscope needs to be developed to be able to perform a pure NOTES cryoablation by introducing the cryoprobe through the endoscope.

The aim of the NOTES procedures is not to reproduce laparoscopic surgery but to perform minimal and limited dissection of the kidney tumour and immediate surrounding tissue. We think that a NOTES robotic platform coupled with a surgical navigation system will advance the field and bring NOTES to a clinical daily reality.

In conclusion, NOTES can provide adequate surgical dissection for safe and effective percutaneous renal cryoablation under direct videoscopic monitoring at kidney locations otherwise not accessible percutaneously. Both transgastric and transvaginal approaches can be used effectively in the porcine model, to perform renal cryoablation providing a minimally invasive scar-less surgery.


Jihad H. Kaouk is a Lecturer and Proctor for Endocare Inc. Source of funding: Internal funding only.