First described by Jacobs et al., laparoscopic colectomy has proved to be a safe and feasible approach for both benign and malignant surgical conditions of the colon. In fact, the laparoscopic approach has become standard for colon resections in most circumstances. Numerous studies have confirmed advantages of the laparoscopic approach when compared to an open procedure, including decreased postoperative pain, reduced incidence of ileus, enhanced recovery of pulmonary function, reduced immunosuppression, decreased length of hospital stay, improved cosmesis, and earlier return to work and normal activities. In addition, laparoscopic colon resection has shown equal or improved survival in the setting of malignancy. Laparoscopic techniques can be employed for the entirety of an operation or for specific portions. It is the authors’ preference to perform a laparoscopic-assisted procedure in most circumstances. The dissection is completed in a laparoscopic manner, including division of the mesentery and complete mobilization of the affected colon, and the anastomosis being performed extracorporeal. Using this technique, the specimen is delivered through a small abdominal incision. A hand-sewn or stapled extracorporeal anastomosis can then be performed, or the anvil of a circular stapler secured in place in the proximal bowel in preparation for an intracorporeal anastomosis.

Laparoscopic left colon dissection has been described in both lateral-to-medial and medial-to-lateral manner. Open left colon resections were traditionally performed in a lateral-to-medial direction, and initial descriptions of laparoscopic left colon resections also involved lateral-to-medial dissection. Medial-to-lateral dissection was first described in 1994 by Milsom et al., and as surgeons have become more comfortable and adept with laparoscopic techniques, a medial-to-lateral dissection has become preferred in many situations. The advantage of a medial-to-lateral approach is that the natural peritoneal attachments of the right and left colon are left intact during central division of the vascular structures and mesentery near their origin and thus serve to keep the colon retracted laterally during the medial dissection. Although a statement issued by the European Association of Endoscopic Surgeons (EAES) in 2004 endorsed a medial-to-lateral approach as preferred, it was based on level 5 evidence and was a grade D recommendation. Despite this conclusion, the lateral-to-medial dissection continues to have utility and provides the surgeon flexibility in determining the optimal approach to a given clinical scenario.

This chapter has been written to discuss and illustrate technical tips employed by the authors to perform a laparoscopic lateral-to-medial left colon dissection, and indications for using these techniques.

Laparoscopic colon resection is superior to open resection and has become the current standard of care in colon resection for appropriately trained surgeons. Prospective randomized trials have also shown that laparoscopic colon resection yields at least equivalent oncologic results when compared to the open approach. As such, the laparoscopic approach is indicated in benign and malignant conditions alike.

There are no absolute indications or contraindications to a lateral-to-medial approach. One of the strongest indications to proceed with a laparoscopic lateral-to-medial dissection is surgeon familiarity and comfort with this technique. This logic cannot be overstated, because laparoscopic left colon resection is a complex procedure with a demonstrated steep learning curve.

The surgeon should always strive to obtain a broad area of mesenteric dissection to ensure an adequate lymphadenectomy (≥12 lymph nodes) during the resection of a colon cancer. A recent systematic review and meta-analysis suggests that the two approaches are no different in terms of number of lymph nodes harvested or cancer recurrence rates, suggesting that malignancy is not necessarily a contraindication to performing a lateral-to-medial dissection.

Benign conditions of the colon are ideally suited for a lateral-to-medial dissection because lymph node harvest is not a consideration. Exceptions to this statement would be surgery for endoscopically unresectable polyps or in case of inflammatory bowel disease with proven or suspected dysplasia. Diverticular disease is the most common indication for a left-sided colon resection. Diverticular pathology of the left colon can also be approached with a lateral-to-medial or medial-to-lateral dissection. In the setting of recurrent diverticulitis, the chronic inflammatory process surrounding the sigmoid colon often makes dissection very difficult. In this case, if a lateral-to-medial dissection presents itself as safer or easier, it should be taken rather than adhering to a rigid standard of medial-to-lateral dissection.

Another situation in which a medial-to-lateral approach may be preferred is when the operation is being done for inflammatory bowel disease where the base of mesentery is involved by the inflammatory process, encasing the vessels and obliterating the embryological dissection plane. This approach offers the advantage of avoiding injury to vessels or retroperitoneal structures.

Whether the indication for laparoscopic left colectomy is a benign or a malignant condition, proper preoperative planning is essential. Axial, contrast-enhanced imaging studies are often obtained for diagnosis of diverticulitis or malignancy before an operation is undertaken. These imaging modalities can be invaluable in surgical planning to assist the surgeon in anticipating potential intraoperative difficulties. Although the ureter should ideally be intraoperatively visualized during all left colon resections, the location of the ureter relative to a planned resection may be ascertained by intravenous contrast-enhanced computed tomography scan allowing the surgeon to review specific anatomic details before embarking on a potentially difficult dissection. Oral contrast helps identify loops of the small intestine and can help distinguish between bowel and other structures, such as a tumor mass, blood vessel, or a fluid collection. Because oral contrast rarely reaches the left colon and rectum, rectal contrast is particularly useful in defining the lower gastrointestinal anatomy in patients undergoing left colon resection.

Accurate preoperative tumor localization is an important consideration when planning a successful laparoscopic left-sided colectomy for malignancy. In this setting, patients likely have undergone colonoscopic evaluation which led to the diagnosis. If endoscopy was performed remotely, it can be valuable to perform repeat colonoscopy or flexible sigmoidoscopy, when possible, the day before surgery, thus obviating the need for two separate bowel preparations. In preparation for resection for a colon tumor, the lesion should be marked with tattoo ink to aid in localization during surgery. India ink and other carbon-based inks are the most commonly used agents. Although endoscopic localization of right-sided tumors may be facilitated if the lesion is visualized close to the appendiceal orifice and ileocecal valve, there exist no comparable landmarks in the transverse, descending or sigmoid colon. If unable to visualize tattoo ink from previous endoscopic tumor localization, intraoperative colonoscopy can be performed if the site of the lesion is not obvious on inspection of the serosal surface.

Alternatively, or complementarily, preoperative contrast enema can be used to help localize colonic lesions.