Topographic Anatomy of the Colon and Rectum: Tips and Tricks in Laparoscopic and Robotic Surgery

Fig. 3.1

Identification of the ileocolic pedicle

According to the Okuda and Nobuhiko classification (Milsom et al. 2006a), the vascular anatomy of this area may be classified into two types (type A and type B). This classification addresses the need to achieve a complete lymphadenectomy around the origin of IC for advanced right colon cancer and is based on the position of the ileocolic pedicle with respect to the superior mesenteric vein.

In type A, the ileocolic artery is found anteriorly to the superior mesenteric vein (SMV). After mobilization of the ileocolic pedicle from the duodenum, the dissection of the ventral side of the superior mesenteric vein leads to the dissection of the origin of the ileocolic artery.
In type B, the ileocolic artery is behind the SMV. The dissection of the ventral side of the superior mesenteric vein leads to a complete dissection of the root of the middle colic artery and vein.

The right colic vessels are then exposed at the anterior part of the head of the pancreas, respecting Henle’s gastrocolic venous trunk. If an accessory right colic vein is found, it is clipped and divided. If it is difficult to confirm the presence of this variant, this vein may be easily detected later during the mobilization of right flexure.

The patient is now placed in steep Trendelenburg position with the right side elevated to move the small intestine toward the right upper quadrant. The peritoneum is incised along the base of the ileal mesentery upward to the duodenum taking care of the right ureter and gonadal vessels. A wide window is made in the peritoneum inferior to the ileocolic pedicle as the retroperitoneal structures are gently swept away in a posterior direction. The pedicle should be isolated adequately and circumferentially to allow for easy vessel division. The surgeon should clearly identify the duodenum and gonadal vessels to avoid injury (Fig. 3.2). Identification of the right ureter is not always necessary in laparoscopic right colectomy. The division of the ileocolic pedicle can be performed using vessel-sealing energy devices, staplers, or clips per the surgeon’s preference. The level of division of IC vessels will depend on the surgical indication. For malignancy, this pedicle should be proximally ligated so as to maximize the lymph node harvest (high ligation). In benign indications such as Crohn’s disease where the mesentery may be thickened, the vessel is divided where it is soft.

Fig. 3.2

Retromesenteric dissection

A medial-to-lateral mobilization of the ileocecal region and right mesocolon is achieved.

Particular caution must be taken during the right flexure mobilization to avoid bleeding especially from around Henle’s trunk. If the accessory right colic vein was previously difficult to detect, at this time it can be easily identified and divided. Accessory right colic vein and the right branches of middle colic vessels are clipped and divided.

Finally, the right flexure and right colon are completely freed laterally, which completes the mobilization of the entire right colon.

Once the entire right colon is mobilized, it is withdrawn through an enlargement of the umbilical port site or through a suprapubic incision. Prior to making the incision, however, the surgeon must ensure adequate reach of the transverse colon to the proposed incision site; otherwise, the surgeon risks an unnecessarily difficult anastomosis or undue tension and tearing of the middle colic vessels. A wound protector is placed to decrease the risk of extraction site recurrence and wound infection. The prepared colon is extracted. Ileal and colic resection is carried out.

The anastomoses are accomplished extracorporeally or intracorporeally (Fig. 3.3) with care to maintain the proper orientation of the duodenum and transverse colon, and avoid twisting of the mesentery.

Fig. 3.3

Intracorporeal anastomosis

The anastomosis is accomplished by aligning the terminal ileum and the transverse colon in an isoperistaltic fashion, then creating an enterotomy and a colotomy and firing a single 60 mm linear stapler cartridge to create the side-to-side anastomosis. Alternatively, a hand-sewn suture may be performed. The enterotomy can then be closed in a running fashion using absorbable sutures.

The bowel is put back into the peritoneal cavity in the case of extracorporeal anastomosis. The wound is irrigated and closed.

The abdominal cavity is reinflated. The ileocolic anastomosis is inspected and the proper positioning of the small bowel checked. The peritoneal cavity is irrigated with saline and checked for bleeding. The mesenteric opening does not usually require closure after a right hemicolectomy as the defect is large and it is uncommon to develop a mesenteric internal hernia. If concern arises for small bowel herniation into the mesenteric defect during the final laparoscopic inspection, the defect can be closed at the surgeon’s discretion. A drain is left in the right parietal fossa per the surgeon’s preference.

Lateral-to-Medial Technique

The dissection is begun either from the area inferior to the cecum and proceeds superiorly or begins at the hepatic flexure and proceeds inferiorly. Most surgeons prefer the cecum as a starting point; the dissection is started by putting appropriate tension on the cecum allowing an incision of the fascia of Toldt to be performed (Fig. 3.4). As the cecum is rotated medially, the right ureter is usually identified as it crosses the iliac artery bifurcation. The duodenum is identified medially as the dissection proceeds superiorly. The location of the ureter and the duodenum should be rechecked repeatedly throughout the procedure. The dissection then follows the cecum and hepatic flexure mobilization up to the identification of the ileocolic and right colic vessels. If clearly identifiable, those vessels may be dissected and divided with vascular staplers. The operation is now performed similarly to the medial-to-lateral technique.

Fig. 3.4

Laparoscopic Toldt’s fascia incision

2.3 Robotic Approach

After diagnostic laparoscopy confirming the feasibility of the colon resection, the patient is placed in the lithotomy position, and the robot is brought from the right side of the patient and docked onto the ports. Both medial-to-lateral and lateral-to-medial approaches can be performed following the steps underlined above for the laparoscopic procedure.

Although a complete understanding of the vascular anatomy is still required, the tridimensional vision and endowrist instruments offer a greater precision during the vascular dissection.

The dissection of the ileocolic pedicle as well as the identification of right gonadal vessels and right ureter may be particularly challenging, especially in obese patients (Witkiewicz et al. 2013).

Once the bowel is fully mobilized, it can be extracted via a minilaparotomy for extracorporeal anastomosis. However, the robotic system enables the surgeon to create an intracorporeal anastomosis more easily and extract the specimen via a Pfannenstiel incision.

The procedure allows a lower colon mobilization with fewer mesentery exteriorization complications such as bleeding and wound infections. A smaller incision is needed to retrieve the specimen with a better cosmetic result and reduced postoperative incisional hernia incidence (Hellan et al. 2009a; Lee et al. 2013a; Pigazzi et al. 2006).

2.4 Tips and Tricks for Right Colectomy

The omental detachment must be begun in the medial part of the transverse colon to facilitate the dissection and should be done in all cancer cases.
The colon may not be properly extracted without prior vessel control. Therefore, the vessels should preferentially be divided intracorporeally
The intracorporeal anastomosis has shown many advantages, especially if performed robotically: ease creation of anastomosis in morbidly obese patients (Raftopoulos et al. 2006), flexibility in location of extraction sites, fewer mesentery exteriorization complications, and avoidance of accidental mesenteric twists (Lee et al. 2013b; Hellan et al. 2009b).

3 Left Colectomy (LC) and Low Anterior Resection

3.1 Indications

Minimally invasive left colon resection is indicated for both benign (Crohn’s disease, diverticulitis, polyp unresectable by endoscopy) and malignant (colon cancer) etiologies.

3.2 Laparoscopic Approach

The patient is placed in the modified lithotomy position with carefully padded Allen stirrups. The legs are oriented so that the toes, knees, and shoulders are all in line. The knees should be slightly flexed and thighs lowered parallel to the bed to allow for a maximum range of motion of the laparoscopic instruments. Positioning of the patient in the operating room should include tucking of both arms by the patient’s side to allow full access to the sides of the patient. The patient needs to be not only carefully padded to avoid any pressure injuries but also carefully secured to the bed to allow extreme positioning changes during the operation. Care should be taken to confirm that the patient’s perineum is low enough off the edge of the table to allow for ~5 cm of exposure needed to allow easy passage of the circular EEA stapler.

The abdomen is then prepped and draped in the usual standard fashion with care taken to position the sterile towels along the anterior axillary line laterally, up to the xiphoid superiorly, and down to the pubis to allow for maximal exposure. The perineum is prepped if transanal extraction or a hand-sewn anastomosis is anticipated.

Note that the trocar positions are shifted down when a low anterior resection is performed.

An adequate exposure must provide an excellent view of the sacral promontory and of the aortoiliac axis. This exposure is particularly important for the medial-to-lateral vascular approach.

Similarly to the RC, the left colectomy can be performed in lateral-to-medial and medial-to-lateral approaches.

3.2.1 Medial-to-Lateral Approach

This approach is begun by placing the patient in steep Trendelenburg position with the left side tilted up to allow for the small bowel to be swept away from the root of the mesentery.

The sigmoid mesocolon is retracted anteriorly and the visceral peritoneum incised at the level of the sacral promontory. The incision is continued upward along the right anterior border of the aorta up to the ligament of Treitz. The mesentery is elevated and the IMV identified and the dissection begun there just lateral to the ligament of Treitz. The IMV is skeletonized circumferentially via blunt dissection from its attachments to the left mesocolon. Once this is achieved, the vessel is then ligated using a vessel-sealing energy device, stapler, or clips per surgeon’s preference. The sigmoid colon is then elevated toward the abdominal wall and the overlying peritoneum medial to the right common iliac artery at the sacral promontory incised. The upward traction is maintained and a plane developed bluntly under the superior hemorrhoidal artery. The left ureter is again identified and swept posteriorly and the dissection continued to the origin of the IMA at the aorta (Fig. 3.5). The IMA is then skeletonized circumferentially and the critical “T”-shaped view of safety achieved. This is comprised of the junction of the left colic artery and superior hemorrhoidal artery with the IMA (Fig. 3.6). The IMA is then ligated using a vessel-sealing energy device, stapler, or locking hemoclips per surgeon’s preference. The left colic artery is also divided in a similar fashion in most patients.

Fig. 3.5

Inferior mesenteric artery identification

Fig. 3.6

The critical “T structure”

The sigmoid mesocolon is retracted anteriorly applying traction during dissection. The avascular plane between Toldt’s fascia and the sigmoid mesocolon can then be identified and easily divided. At this point, it is important to identify the rectosigmoid junction and the ureters. The dissection continues posteriorly and laterally toward Toldt’s line. The sigmoid colon is then completely freed, and the lateral attachments can then be divided using a lateral approach.

In the event that a long segment of sigmoid colon must be resected, mobilization of the splenic flexure is required. The small bowel is repositioned in the pelvic cavity. Traction on the mesocolon of the transverse colon and traction on the adhesions of the splenic flexure will lead to safe division of the splenic flexure.

In the medial approach to the splenic flexure, the posterior attachments of the transverse and descending colon are dissected first. The root of the transverse mesocolon is divided anterior to the pancreas. The dissection plane follows therefore the plane of the previous sigmoid colon mobilization.

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