In the preoperative holding area, patients are given chemical prophylaxis against venous thromboembolism in the form of subcutaneous standard or low-molecular-weight heparin. Sequential compression devices and antiembolic stockings are applied before transfer to the operating table. Intravenous antibiotics with appropriate anaerobic and aerobic coverage are given within 30 minutes of skin incision and redosed at appropriate intervals throughout the operation.

The authors position patients in modified lithotomy position in padded stirrups, with both arms tucked at the sides. Care should be taken to ensure that the lower leg is well protected to prevent injury to the peroneal nerve. An electric operating table is lined with either a gel pad or beanbag to reduce the risk of pressure injury and the patient is secured to the operating table to ensure no movement during periods of extreme tilt and rotation. A “test run” of positioning helps ensure patient position and prevent intraoperative injuries. For coloanal access, it is essential to leave 3 to 4 cm of the buttocks hanging off the edge of the table to allow adequate exposure for the transanal portion of the operation. An orogastric tube is placed for tube gastric decompression. Once positioned, a careful digital examination, proctoscopy, or anoscopy may be performed to confirm the preoperative assessment of tumor margin and ensure that sphincter preservation is feasible. Rectal irrigation is then performed with dilute povidone-iodine solution. Skin preparation of the abdomen, perineum, and perianal region is performed per standard protocol. A Foley catheter is placed after preparation to ensure the entire field is sterile.

The abdomen is entered using an open technique and a 12-mm Hasson port is placed at the umbilicus. Two additional 5-mm ports are placed on the right side of the abdomen under laparoscopic guidance. Although ports are typically placed lateral to the rectus sheath, in a tall patient with a narrow pelvis, placing ports more medially may be helpful to prevent coning of the instruments in the pelvis. One of the ports may be placed through the planned ileostomy site, but often this site is not ideal for a working port. A third 5-mm port is typically required for retraction. This may be placed in the left lower quadrant, suprapubic midline, or upper abdominal midline. An upper midline port has the benefit of allowing the camera operator to stand to the left of the operating surgeon on the same side of the patient and easily retract the rectum or transverse colon with the left hand while controlling the camera with the right. This position is especially beneficial when performing a sub-IMV mobilization of the left colon and splenic flexure. The authors’ typical port placement and operating room setup is shown in Figure 15-2.

An initial evaluation is performed to determine the laparoscopic feasibility of the operation and to evaluate for metastatic disease. If significant adhesions from prior surgery exist, the surgeon must decide to attempt laparoscopic lysis or to convert to open surgery. The peritoneum is inspected for signs of tumor implantation in all four quadrants. The diaphragm is examined as is the capsule of the liver, including the inferior aspects by elevating the left and right lobes. The ovaries are inspected because there is a 3-8% incidence of ovarian metastasis in colorectal cancer patients. The pelvis is assessed to evaluate for lateral extension of the tumor, although this may be difficult to determine until the pelvic dissection begins.

The patient is placed in the Trendelenburg position, with the right side down and the small bowel is reflected out of the pelvis. Occasionally, right-sided adhesions prevent retraction of the cecum and small intestines. Lysis of these adhesions helps provide a clear window into the pelvis and prevent small bowel migration into the operative field. The sigmoid colon is reflected anteriorly and to the left by the assistant to place the right side of the mesorectum on stretch. If the sigmoid is adhesed to the anterior pelvis, it may be necessary to free these attachments as well to provide adequate reduction of the sigmoid out of the pelvis. The peritoneum overlying the right side of the mesorectum distal to the IMA is opened over the sacral promontory. The superior hemorrhoidal vessels are elevated into the open space exposing the presacral vessels and nerves (Fig. 15-3). Branches of the hypogastric nerves lying between the aorta and the IMA are preserved and swept caudally toward the aorta. The left ureter is identified in its retroperitoneal position along the left pelvic sidewall beneath the vessels. If difficulty is encountered elevating the proximal rectum to perform this medial-to-lateral dissection, it may be beneficial to divide the lateral or anterior attachments to the sigmoid colon. The origin of the IMA is traced back to the aorta, just caudal to the ligament of Treitz, and is isolated circumferentially, preserving lymph nodes with the specimen. The IMA is transected using a stapler, clips, or an energy device. It is essential that the left ureter has been definitively identified and preserved before transection of the vessel.

The left colon mesentery is then further mobilized in a medial-to-lateral manner, lifting the mesocolon off of the retroperitoneum. The bare area of the left colon mesentery is divided cephalad from the IMA origin along the anterior surface of the aorta, medial to the IMV, elevating the IMV and the ascending left colic artery in the process (Fig. 15-4). High ligation of the IMV is essential for adequate length on the descending colon. The vessel should be isolated and divided near the inferior border of the pancreas where it dives posterior to converge with the splenic vein. The left colic artery may then be divided at the bifurcation of the left colic and superior hemorrhoidal, leaving the IMA origin and superior hemorrhoidal with the specimen and preserving any branches from the left colic artery to the descending colon.

Dissection proceeds in a medial-to-lateral direction, under the transected IMA and IMV. The retroperitoneum can be maintained intact and swept caudally, preserving the left ureter, gonadal vessels, and psoas muscle intact. This dissection continues from the pelvic brim inferiorly to the inferior border of the pancreas superiorly and laterally to the white line of Toldt. After mobilizing the left
mesocolon off of the retroperitoneum, the colon is retracted medially and the lateral attachments are divided along the length of the descending colon. The plane of transection should be just medial to the white line of Toldt to leave the retroperitoneum undisturbed.