Left-Sided Colon Resections: Unique Considerations and Optimal Setup
(a) Robotic sigmoid Si port placement for anticipated splenic flexure takedown. (b) Robotic left/sigmoid colectomy, da Vinci Xi® (Intuitive Surgical, Sunnyvale, CA, USA) port placement
Figure 19.1b shows a modification of the trocar outline when the entire left side (left and sigmoid colon) is the target of the operation.
Xi® Robot (Intuitive Surgical, Sunnyvale, CA, USA)
For the Xi system , the ports have a different layout and should be placed on a straight line from left upper to right lower quadrant. The slope of the line may be steeper if the splenic flexure needs to be taken down and flatter if that step is not anticipated. The space between arms should be an equal distance of 6–8 cm. In contrast to the previous setting, the ports/arms in the Xi are labeled as 1–4 from left to right (Fig. 19.2). The standard robotic port including the one for the camera is 8 mm; stapler insertion requires a 12 mm port (typically arm 4) with an 8 mm reducer when used for the other instruments. The specimen extraction and anvil insertion site may be planned as one of the existing ports or as a separate small Pfannenstiel incision in the suprapubic region.
Docking of the Robot
After trocar placement, the patient is positioned in Trendelenburg and with the left side up just enough to move the small bowel out of the pelvis and expose the root of the left colon mesentery.
The Si robot has less flexibility, and the cart needs to be docked in an oblique angle (approximately 30 degrees) from the left hip. The base of the robotic cart is aligned parallel to a virtual line between the most outer trocars in the left flank and right lower quadrant (Fig. 19.1a). It is important to position the left leg in the stirrup such that it will not interfere with the robotic arm movements after the patient is positioned in Trendelenburg position and tilted to the right. The Si system will allow reasonable access to two quadrants involved in the operation. If the ports are configured for a lower pelvic operation, access to the pelvis and a portion of the left hemi-abdomen will be possible without repositioning. If the splenic flexure needs to be mobilized, three options exist:  arm 3a is undocked and rotated into the 3b position (Fig. 19.1a),  the robotic cart may need to be redocked over the left shoulder, or  the splenic flexure is mobilized laparoscopically. Once the Si robot has been docked, it needs to be manually targeted to the area of interest.
As the Xi robot has a central boom that allows for 360 degrees rotation, it can be docked from any direction, typically though from the left. First, the boom is centered and then docked to the camera port (arm 3) only. The camera is inserted and pointed at the surgical target. The boom and the other arms are automatically optimized using the integrated targeting function. The other arms are docked and adequately spaced.
Instrumentsshould be carefully inserted, best under visual control or by testing the direction first by means of a nontraumatic laparoscopic peanut. With either system, the right hand typically controls an energy device (monopolar scissors, hook, or bipolar vessel sealer) through the right lower quadrant port. The left hand directs two retracting instruments (fenestrated bipolar forceps, Cadiere forceps or tip up, fenestrated graspers). These instruments are frequently adjusted utilizing the foot switch to allow for optimal traction and countertraction. Much of the exposure is achievable without the assistant surgeon and is considered one of the major benefits of robotic compared to laparoscopic approaches.
CME Dissection of the Colon Mesentery and Isolation of the Mesenteric Root
When the goal is to perform an oncological resection, the procedure follows the same steps as described for the laparoscopic approach. Please refer to Chap. 11 on Principles of Complete Mesocolic Excision (CME) for Colon Cancer.
Depending on the location of the pathology and whether left colectomy is performed for benign or malignant indications, different levels of vascular dissection are needed. The dissection usually commences with retracting the rectosigmoid colon upwards to tent up the inferior mesenteric artery (IMA) pedicle towards the anterior abdominal wall (Fig. 19.3). The two robotic arms from the left side and a laparoscopic grasper through the assistant trocar can be utilized to achieve optimal tension on the peritoneum. This will allow CO2 dissection to better identify the dissection planes defined by embryological anatomy. Wide scoring of the peritoneum overlying the base of the left colon mesentery starts at the peritoneal groove on the right side of the lateral mesorectum and continues towards the inferior border of the inferior mesentery artery (Fig. 19.4). Subsequent adjustment of the robotic arms with lifting the rectosigmoid colon and by passive upwards retraction with the instrument shafts from beneath the colon wall will expose the areolar tissue between the sigmoid colon mesentery and all retroperitoneal structures. This dissection continues from medial to lateral until the IMA and inferior mesenteric vein (IMV) are completely mobilized, the left ureter is identified close to the mesenteric root, the hypogastric nerves identified and preserved, and the lateral peritoneal reflection is reached. The dissection is performed along the embryological planes of the visceral and parietal peritoneum to yield an intact mesocolon (complete mesocolic excision).
At this point, the decision has to be made whether the IMV will be ligated next to the artery or higher near the duodenum (see Fig. 19.5, which demonstrates high ligation of the IMV). This step is most commonly used during low anterior resection (LAR) and will be described in detail in Chap. 24 on Robotic Low Anterior Resection. The entire pedicle is encircled, and high ligation of the IMA and IMV is performed with the robotic vessel sealer or stapler after being individually dissected and skeletonized. Alternatively, the left colic artery can be preserved and ligation of the superior rectal artery only performed just distal to its runoff.
With few exceptions, it is recommended to follow the natural planes regardless of the indication for left colectomy. The ability to consistently and intentionally dissect, isolate, and divide the IMA, left colic artery, and superior rectal artery is invaluable and mandatory for malignant disease. Even for confirmed benign disease, dissection along these planes is often easier and less bloody than dissecting through the mesentery. In addition, a high ligation increases colon mobility which is needed for lower anastomoses.
A non-anatomic “wedge resection” along the bowel wall may on occasion be preferable in proven benign disease with severely altered anatomy (Crohn’s colitis, severe diverticulitis) and is technically facilitated using vessel sealing devices. For more details and techniques, please refer to Chap. 5 on Laparoscopic Left Colon Resection for Complex Inflammatory Bowel Disease.
The dissection continues with a medial to lateral mobilization of the descending colon mesentery off Gerota’s fascia. If the splenic flexure is mobilized for a tension-free anastomosis, the inferior border of the distal pancreas should be recognized to maintain the dissection plane anteriorly (Fig. 19.6). The sigmoid and descending colon is now retracted medially to divide a thin remaining layer of peritoneum along the line of Toldt. This dissection is continuous from lateral to medial for the splenocolic ligament. Alternatively, the lesser sac is entered from medially, and the omentum and splenocolic ligament are divided starting from the distal transverse colon (Fig. 19.7). Upon complete mobilization of the descending colon and the splenic flexure, the peritoneum lateral to the rectosigmoid junction is scored, and a window is created using blunt dissection along the posterior wall of the colon. This allows transection of the rectosigmoid colon with a robotic stapler through the right lower quadrant port. The remaining mesentery is divided to the planned proximal transection. Bowel perfusion can be assessed with indocyanine green injection and the fluorescence imaging mode of the robotic camera. For additional details on perfusion assessment for left-sided anastomoses, refer to Chap. 29 on Minimizing Colorectal Anastomotic Leaks.