Surgery
The procedure is initiated with either a lateral to medial or medial to lateral dissection of the sigmoid and its mesentery. With a medial approach the mesentery is scored at the sacral promontory and the dissection is continued laterally, mobilizing the superior hemorrhoidal off the retroperitomeum. The left ureter is identified and swept inferiorly and after ureter identification the inferior mesenteric artery is ligated at its origin off the aorta. The dissection is continued superiorly and the inferior mesenteric vein is divided. The colonic mesentery can then be freed from the retroperitonuem and the final step is diving the white line of Toldt. A lateral mobilization starts by mobilizing the colon and mesentery off the retroperitoneum. After mobilization is complete the mesentery is scored on the right side at the sacral promontory and the inferior mesenteric artery is followed to its origin and divided as mentioned above. If the colon is foreshortened or more length is needed, as occurs with obese patients, mobilization of the splenic flexure may be performed. Mobilization of the slenic flexure is recommended for all low anterior resections to provide adequate reach to the distal rectum or anus.
Low Anterior Resection
Unlike APR, anterior resection of the rectum with colorectal or coloanal anastomosis requires intra-corporeal division of the low rectum, extraction of the specimen through an abdominal incision, and construction of anastomosis. Division of the distal rectum can be challenging; frequently the angle of the stapler is suboptimal and multiple fires of the stapler are required to divide the rectum. Advances in laparoscopic instrumentation have made this step easier. Generally the specimen will be extracted through a small abdominal incision. Location of the incision depends on surgeon preference (periumbilical, lower midline, pfannisteal). As anterior resections require a small incision, both hand-assist and hybrid (laparoscopic mobilization of the splenic flexure and division of the inferior mesenteric artery and vein with open proctectomy and anastomosis) have been embraced in addition to the straight laparoscopic proctectomy. The anastamosis can either be created via the extraction incision or the pneumoperitoneum can be re-established and the anastomosis laparoscopically created. The total mesorectal mobilization can be laparoscopically completed and utilizing the laparoscope can give excellent visualization. The authors use a diamond-shaped port placement to obtain adequate retraction and exposure for dissection of the mesorectum. This can be difficult in some patients, primarily obese individuals with narrow pelvises.
Outcomes after Laparoscopic Proctectomy Initial small randomized studies raised concern about the outcomes after laparoscopic proctectomy for cancer. One of the early studies (CLASICC trial) reported higher rates of positive surgical margins in the laparoscopic group compared with open group.2
Additionally, two
randomized studies have suggested that sexual dysfunction may be worse after the laparoscopic approach. Thus, in the US, a randomized controlled trial comparing laparoscopic and open proctectomy for rectal cancer has been initiated by the American College of Surgeons Oncology Group (ACOSOG). In the past year, groups from around the world have reported long-term outcomes of their single-institution series of laparoscopic proctectomy. Ng et al. (China) reviewed the short- and long-term outcomes in 579 cases performed in a single institution over 15 years (1992–2007). Although the patient population was heterogenous in terms of stage, overall morbidity was 18.8%
88
(early) and 9.7% (late) with a 3.5% anastomotic leak rate. There were two port site recurrences and overall local recurrence was 7.4%. Bianchi et al.17
followed 109 patients who underwent anterior resection for rectal cancer between 1999 and 2005. A conversion rate of 18.7% was observed with overall morbidity of 27% and anastomotic leak rate of 13.5%. The circumferential and distal margins were negative for tumor in all cases; the mesorectum was assessed as intact in 91% of cases and disrupted in 1.9% (two cases).17
Milsom et
al. (USA) investigated mid- and lower-third rectal cancers between 1999 and 2006 in 103 patients: 58 hand assisted and 45 laparoscopic. Although most were early-stage cancers (stage 0 and 1), the conversion rate was low (2.9%) and the anastamotic leak rate was similar to open lower anterior resection (LAR) (7.8%). Ninety-one percent of the cases had a negative radial margin.18
These recent
studies suggest that, in expert hands, well-selected patients can be successfully treated with laparoscopic proctectomy for rectal cancer with results similar to open proctectomy. The forthcoming randomized controlled ACOSOG trial comparing open and laparoscopic proctectomy will provide additional data as to the feasibility and oncological outcome of laparoscopic proctectomy.
Robotic Proctectomy
Recently, robotic surgery has undergone major advances. At present there is only one system for performing robotic surgery, the Da Vinci® Robot, Intuitive Surgical, Sunnyvale, CA. As of December 2007, 795 units had been delivered worldwide, 595 of them in North America.5
Robotic
pelvic surgery has been embraced by the urology community and, currently, radical prostatectomy is the most frequently performed robotic procedure; in the US in 2007 50,000 prostatectomies were performed with the Da Vinci robot, accounting for approximately 60% of prostatectomies carried out in the US.19
By introducing ‘wristed
instruments’, the robot helps restore the six degrees of freedom of the human hand and facilitates complex surgical procedures in confined spaces such as the pelvic cavity.
The current robots are limited to working in one abdominal quadrant at a time so if one wishes to work in multiple quadrants the device often has to be relocated or placed at an angle, limiting access to the lateral- most aspects of each quadrant. To work in two separate quadrants the robot needs to be undocked, repositioned, and re-docked. The patient’s position on the table must be set prior to docking with the robot, therefore the table position cannot be adjusted to facilitate exposure as the dissection progresses. Adjusting the table position is integral in laparoscopic colorectal surgery as it facilitates ‘retraction’ of the small bowel out of the operating field. The robot does not appear to decrease recovery time, shorten hospital stay, or hasten resumption of diet compared with laparoscopic surgery.20
The complex instrumentation
and longer operative time means that robotic surgery is associated with significantly increased costs compared with standard laparoscopy. The increased operative time and costs, with little perceived benefit over standard laparoscopy, has limited widespread acceptance of the use of the robot for colonic resections. The robot does not provide tensile feedback to the surgeon and the robotic graspers can generate significant force that can injure the intestine, large vessels, or mesentery. These limitations must constantly be kept in mind to prevent complications when performing robotic resections.
US GASTROENTEROLOGY & HEPATOLOGY REVIEW
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