All tissues and organs are covered with connective fibers, the so-called “fascia.” Dissection means the dividing of these fibrous tissues between the other tissues or organs, creating new fasciae on both sides (Fig. 6.2a). Your dissection between the rectum and the neural system, such as the hypogastric nerves, the pelvic nerve plexus, and the neurovascular bundles, creates the so-called “prehypogastric nerve fascia” (fibrous tissues covering the nerves) and the “rectal fascia propria” (fibrous tissues covering the rectum and its proper adipose tissue). A good counter-traction is a prerequisite to identify the fibrous tissues. You may divide the adipose tissue intentionally only at the time when you divide vascular or neural branches to the rectum, because these branches are accompanied with the adipose tissues.

The greater omentum and the transverse colon are placed in the left upper quadrant, and the small bowel loops are placed in the upper right quadrant to expose the terminal portion of duodenum and the inferior mesenteric vein (IMV) (Fig. 6.3).

Sigmoid colon and rectum are retracted out from the pelvis to identify the tumor location. If the tumor location is unclear, proctoscopy or colonoscopy is recommended to exactly determine the distal cutting line of the rectum. Preoperative tattooing is not recommended because the ink often exudates extramurally to make dissection layer obscure.

The anterior wall of the rectum and the pedicle of superior rectal vessels are grasped gently and retracted ventrally by the assistant to extend the right-side peritoneum of rectum widely (Fig. 6.4). If the grasping of the anterior wall of the rectum is difficult, the assistant can push the rectum ventrally and laterally with an opened intestinal grasper (Fig. 6.5). An incision is made on the peritoneum at the level of promontory, going toward the peritoneal reflection (Fig. 6.6). Picking up the cutting edge of peritoneum facilitates the recognition of the subperitoneal connective fibers (Fig. 6.7). Cutting these fibers, not the adipose tissues, prevents the injury on the hypogastric nerves. Even if you are dissecting a wrong plane with dividing the fibers, it is able to easily return to a correct plane without any oncological as well as physiological complications.

Cutting of these fibrous tissues creates fibrous membranes on both sides: the so-called rectal fascia propria (proper rectal fascia) and prehypogastric nerve fascia (Fig. 6.8). You can advance the dissection as deep as possible toward the pelvic floor. If it is difficult, you should move to cephalad dissection. Incision of peritoneum is continued up to the origin of IMA. The assistant should now grasp the IMA pedicle proximally to extend subperitoneal connective tissues. This maneuver facilitates the recognition of fine structure of connective fibers and prevents the injuries to the lumbar splanchnic nerves, the ureter, and the gonadal vessels (Fig. 6.9). The borderline between the lymph nodes along the IMA and the lymph nodes along the aorta is unclear so that you should make the border yourself dividing the adipose tissues between them. I recommend an ultrasonic or a bipolar energy device to divide the adipose tissues. It is safe and easy to dissect between adipose tissues containing lymph nodes and neural tissues surrounding the IMA (Fig. 6.10). You should divide the sigmoidal branches of the lumbar splanchnic nerves, especially the branches from the right lumbar splanchnic nerves, to skeletonize the IMA. Following the skeletonization and division of the IMA, the sigmoidal branches from the left lumbar splanchnic nerves are identified and divided (Fig. 6.11). Or you can divide the IMA distally to avoid the injury to the left splanchnic nerves (Fig. 6.12).

The assistant now grasps the distal edge of IMA and retracts it ventrally to extend the dissection plane between the sigmoidal mesentery and retroperitoneum. The inferior mesenteric vein (IMV) and the left colic artery (LCA) are divided at the same level of the IMA division. In some case the LCA is running far away from the IMV [1]. The dissection between the mesocolon and the retroperitoneum is advanced laterally and cephalad. Again the dissection means cutting of the connective fibers. In order to recognize these connective fibers, counter-traction is very important. Your own ventral retraction often extends the fibrous tissues between the sigmoidal mesocolon and the retroperitoneum (Fig. 6.13). Dividing the connective fibers creates a fibrous membrane covering the left kidney, the so-called the Gerota’s fascia. You can recognize the lower border of pancreas.

Following the cephalad dissection, you come back to the posterior dissection of the rectum. The assistant grasps the distal edge of the IMA by the left hand and the right edge of the incised peritoneum of the mesorectum by the right hand (Fig. 6.14A, B). The following ventral and cephalad traction by the assistant extends the fibrous tissues between the mesorectum and the retroperitoneum (Fig. 6.14C, C′). The dividing these fibers creates the rectal fascia propria and the prehypogastric nerve fascia on both sides.

Chapter 5 Laparoscopic left sided colectomy (mobilization of splenic flexure and sigmoidectomy)