Low Anterior Resection for Rectal Cancer: TME Planes and Surgery of the Upper and Mid-Rectum

Fig. 23.1

Surgeon and room setup

Port Placement (Fig. 23.2)

If you prefer a 10 mm camera, the umbilical port will need to be upsized to a 12 mm port size. On occasion, placing the camera in another port may be required, and these ports will also need to be upsized or an additional 5 mm camera opened.
The midline 5 mm port can usually be hidden in the upper ridge of the umbilicus; however, if the distance between the umbilicus and suprapubic region is relatively short, then the optical field of view may be limited. In these cases, placing the midline port a few centimeters superior the umbilicus is an option.
If planning to fashion an ileostomy, the 12 mm RLQ can be placed at the lateral margin of the predetermined ileostomy site. Care should be taken not to place the 12 mm RLQ port adjacent to the planned ileostomy site as this may result in difficulty pouching the stoma.
It is recommended to close the fascia on all 12 mm port sites due to hernia risk.

../images/465809_1_En_23_Chapter/465809_1_En_23_Fig2_HTML.png — Fig. 23.2

Port placement

Other Equipment/Incisions

Extraction site: Several options exist for the extraction site . We prefer a Pfannenstiel incision because it can usually also allow direct access to the anastomosis in cases in which repair of an anastomotic defect is required. It is also associated with a very low rate of hernia risk. Other extraction sites, however, can be used such as an umbilical site or the left lower quadrant. In cases in which we plan to perform an ileostomy, we use the ileostomy site as extraction site.
Camera : A 5 mm 30 degree or flexible tip camera is preferred.
Instruments : Atraumatic bowel graspers are required. It is recommended to have extended length graspers available.
Energy devices: Monopolar energy devices include the L or J hook, spatula, or scissors with cautery. Thermal energy can include various devices designed to control vessels up to 7 mm size, such as a bipolar device or ultrasonic device.

Operative Technique and Surgical Steps

Planes of the Mesorectum

Both medial-to-lateral and lateral-to-medial approaches are utilized during the laparoscopic procedure. The procedure is preferably initiated in a medial-to-lateral fashion to identify the critical landmarks and develop the proper planes of mesenteric dissection. The medial side of the mesentery is exposed by elevating the rectosigmoid with a bowel grasper to identify the thin base near the sacral promontory. The peritoneum is carefully scored and the avascular presacral plane is dissected. Pneumodissection in the alveolar tissue signifies the correct plane between presacral fascia and the fascia propria of the rectum. The superior rectal artery (SRA) is identified and elevated to further expose the plane of dissection (Fig. 23.3). The left ureter and gonadal vessels are exposed very early in the dissection. The avascular plane is dissected further while elevating the SRA taking care not to injury the nerves in the deeper plane. Dissection continues laterally in the retroperitoneal plane toward the white line of Toldt, inferiorly to the level of the sacral promontory and superiorly toward the base of the IMA. At this level, the peritoneal plane is scored in an upside-down “U” fashion, starting at the base of the bifurcation, sweeping up as it follows the vessel’s course into the pelvis, and then extending distally to where the anterior reflection terminates laterally in the pararectal gutter.

../images/465809_1_En_23_Chapter/465809_1_En_23_Fig3_HTML.png — Fig. 23.3

Medial-to-lateral dissection with elevation of the superior rectal artery (SRA) and exposure of the retroperitoneal plane

The plane between the retroperitoneal structures posteriorly and the mesorectum anteriorly is then developed. Dissection from the CO₂ insufflation again helps identify this avascular plane; after infiltrating into the tissues, they appear as white, crackly fibers. After sweeping over the sacral promontory from right to left, it is important to remember that the lateral retroperitoneal structures of interest, specifically the ureter, gonadal vessels, and internal iliac artery and vein, lie slightly superior to the presacral fascia. Therefore, the surgeon has to be careful to not proceed in so linear a fashion as to injure these structures. The dissection plane will be identified quite high on the edge of the mesorectum when dissecting the lateral-most area.

In order to avoid creating a tunnel when performing the above dissection, the surgeon should periodically reexamine the right peritoneal edge and continue to open up the triangle that forms between the aorta and IMA pedicle, scoring the peritoneum in a radial fashion right up to the IMA take off. The surgeon will encounter small bridging nerves in this area. These should be preserved if possible or ligated as anteriorly as possible.

In order to preserve planes and perform a meticulous dissection, many use hot scissors, L hook, or thermal energy device tip to carefully dissect between planes. The use of thermal or bipolar energy is typically not used to establish the planes of dissection and is reserved to control bleeding or division of vascular pedicles.

Once the vascular pedicle has been adequately skeletonized, and the surgeon has ensured that the left retroperitoneal structures at risk (i.e., ureter, gonadal vein) are lateral, the vessel can be divided (Fig. 23.4). Either a low (preserving the left colic (LCA) and/or sigmoid branches) or high ligation of the IMA and inferior mesenteric vein (IMV) is then performed (Table 23.1). If performing a low ligation, care is taken to dissect the mesenteric lymph nodes in the fatty tissue along the base of the IMA and draw this tissue into the resection margins so as not to leave behind draining lymph nodes (Fig. 23.5).

../images/465809_1_En_23_Chapter/465809_1_En_23_Fig4_HTML.png — Fig. 23.4

Isolation of the inferior mesenteric artery (IMA) with dissection of the para-aortic lymph nodes

Table 23.1

Oncologic and functional outcomes of high versus low IMA ligation during LAR for rectal cancer

Matsuda et al. GI tumors 2017 [5]	N = 100, ‘08-‘11. RCT: high vs. low ligation in LAR for rectal cancer	NS: OS, DFS (including stage III), # LN 16.7 vs. 14.9
Matsuda et al. BJS 2015 [6]	N = 100, ‘08-‘11, TCT: high vs. low ligation in LAR for rectal caner	NS: defecatory dysfunction, FIQOL, fecal incontinence, anastomotic leak, 16% vs. 10% (p = 0.42)
Fujii, et al. BJS Open [7]	N = 331, ‘06-‘12, RCT: high vs. low ligation	NS: anastomotic leak, 17.7% vs. 16.3%
Mari et al. Ann Surg 2018. (HIGHLOW trial) [8]	N = 214, ‘14-‘16, RCT: high vs. low ligation	Low ligation: significant for better continence, fewer urinary symptoms (p < 0.05 @ 1 and 9 months), better QOL and sexual function NS: anastomotic leak: 8.1% vs. 6.7%

RCT randomized controlled trial, OS overall survival, DFS disease-free survival, FIQOL fecal incontinence quality of life, NS not significant, LN lymph nodes

../images/465809_1_En_23_Chapter/465809_1_En_23_Fig5_HTML.png — Fig. 23.5

Low IMA ligation with lymph nodes in specimen and preservation of the LCA

The surgeon then continues the mesenteric transection up to the site of planned proximal colonic division, which can be immediately performed via endoscopic stapler or via the extraction site. In the case of a particularly bulky colorectal mesentery, early bowel division can improve visualization when performing the pelvic dissection.

Splenic Flexure Mobilization

Additional length of the proximal colon may be needed to perform the anastomosis in a tension-free fashion. If so, we generally use the sub-IMV approach, either before or after IMA ligation, to accomplish this. With this technique, the patient is placed in slight reverse Trendelenburg position. The key is to carefully sweep the small intestine right lateral and cephalad to expose the ligament of Treitz. It is helpful to have the assistant retract the transverse colon cephalad to expose this area. The surgeon then identifies the IMV and incises the peritoneum in a horizontal fashion posterior to the vein along border of the ligament of Treitz. The retroperitoneal plane deep to the vein is then developed, and the vein is isolated and divided. The borders of the retroperitoneal dissection plane are the white line of Toldt along the descending colon (lateral), the inferior border of the pancreas (superior), and the origin the left colic artery (inferior). When dividing the IMV, allow for 1–2 cm cuff of vessel to avoid retraction of a bleeding vein beneath the pancreas should ligation be inadequate. We have found that the sub-IMV technique allows for easier identification of the dissection planes around the pedicle. For more details on various approaches for splenic flexure take down, please refer to Chapter 4 on splenic flexure release.

Lateral Dissection

Prior to starting the pelvic dissection, we then complete the lateral dissection. We initiate this dissection along the sigmoid colon and continue in a cranial fashion. If the sub-IMV approach has been accomplished, the peritoneal attachments will be well defined and separated from the retroperitoneal plane. The best way to accomplish the lateral dissection is to have the assistant gently retract the proximal colon medial and cephalad to expose and stretch the peritoneal refection. The surgeon uses an atraumatic instrument to push the colon medially for counter-traction (it is important to guide trainees with this technique as their instincts are often to traumatically grasp the mesentery), putting the peritoneal attachments on tension (Fig. 23.6). This will allow for efficient division of these attachments all the way up to the splenic flexure, staying just medial to Gerota’s fascia.