♦ Familiarity with the vascular anatomy of the right colon is essential to the safe conduct of a minimally invasive right colectomy (Figure 20-1). Vascular anatomy also significantly determines resection of colonic malignancies. Several key points guide the laparoscopic surgeon:

Venous and lymphatic drainage run in tandem with named mesenteric arteries.

The ileocolic artery (ICA) branches from the superior mesenteric artery (SMA) just over the duodenum after the take-off of the middle colic artery (MCA). It courses obliquely through the mesocolon to terminate at the cecum, giving off a terminal ileal branch that joins with the small bowel arcade from the SMA.

The right colic artery is usually a branch of the ICA rather than arising from the SMA as is historically depicted.

The MCA proper is typically quite short, branching into two or more arteries (right branch, left branch) just 1 to 2 cm from the aortic origin of the SMA. Rarely is the main MCA itself divided in colon resections. The significant hazard of attempts to control bleeding from a transected main MCA is injury to the SMA.

The branches of the MCA are most easily identified from the cranial aspect of the proximal transverse mesocolon. Once these branches and the adjacent mesocolon are transected, the origin of the ICA can be seen retroperitoneally, as can the more medially oriented SMA.

♦ The embryologic fusion plane originates laterally at the white line of Toldt, which occurs where the parietal peritoneum fuses with the visceral peritoneal reflection around the colon and its lateral extension (Figure 20-2). The correct dissection plane is the bloodless embryologic fusion plane. When properly mobilized in this plane, the colon reflects medially on its mesentery to become a nearly midline structure. When the dissection is carried posteriorly past the white line of Toldt, violating the parietal peritoneum as it extends across the retroperitoneal structures, the ureter and gonadal vessels are put at risk and mobilization of the colon is limited.

♦ Awareness of the relationships between the cecum, ascending colon, hepatic flexure, and proximal transverse colon to neighboring structures helps to maintain orientation during surgery and prevents injury:

The duodenal sweep can be appreciated medial and caudal to the hepatic flexure mesocolon. Risk of injury to the portal triad can be averted by avoiding performance of a Kocher maneuver.

The right kidney and Gerota’s fascia are just lateral to the distal ascending colon. Dissection lateral to the embryologic fusion plane can lead to mobilization of the kidney or the second portion of the duodenum (Kocher maneuver).

The right ureter descends retroperitoneally and is not typically exposed unless dissection is carried posterior to the embryologic fusion plane.

The lesser sac must be entered in order to take down the hepatic flexure and transect the transverse mesocolon and MCA branches. The stomach, the gastrocolic, and the hepatocolic ligaments constitute its anterior boundary. Posteriorly, one finds the pancreas and, to the right, the duodenal sweep.

The liver and gallbladder are superior to the hepatocolic ligament. Failure to appreciate this plane can lead to dissection of the porta hepatis.

♦ Surface anatomy considerations principally help with optimal port placement:

Preoperative knowledge of a redundant transverse colon would suggest more caudal placement of the periumbilical hand port incision.

A shift of the hand port site superiorly helps in patients with a relatively long distance between the xiphoid and the umbilicus.