Surgery begins with the mobilisation of the left colon and sigmoid. The peritoneum over the lateral part of the descending colon and sigmoid colon has to be divided along the line of attachment of the peritoneum to the sigmoid colon mesentery. It can be best achieved by using electrocautery or sharp dissection with scissors. Careful preparation allows us to enter the avascular, alveolar space of the left iliac area with its structures: left urethra crossing iliac common artery and vein as well as iliopsoas muscle. At this point the descending colon and sigmoid can be gently mobilised and colonic vessels separated from the urethra. Identification of the left urethra is one of the crucial points of the operation because it can be easily injured while the operation advances. The incision of the peritoneum has to be extended downward to reach the posterolateral aspect of the left side of the pelvis. On the right side the division of the peritoneum has to be carried out over aorta and right posterolateral aspect of the pelvis. This incision should expose the origin of the inferior mesenteric artery and vein. The dissection and ligation of the mesenteric vein should be done first to prevent the spread of tumour cells into the bloodstream during manipulation of the rectum. The level of the dissection of the mesenteric artery is very important. The sympathetic trunks along the aorta send sympathetic nerves medially to the anterior surface of the abdominal aorta and form inferior mesenteric plexus at the level of inferior mesenteric artery. In order to prevent nerve damage, high ligation of the inferior mesenteric artery has to be done. The transection line should be roughly 1-2 cm distant from the aorta. This level represents also the cranial boundary of the mesentery lymph node package; lymph node metastases are rarely found at the point of origin of artery.
After dissection of the mesentery vessels, pelvic dissection commences. The dissection should begin laterally and to the right of the promontory; at this point the identification of the avascular "holy plane" is best performed. Identification of the holy plane is a prerequisite for the surgical procedure. It should be done under direct vision and tearing of the mesorectum should be avoided. Below the aortic bifurcation, presacral sympathetic nerves form the superior hypogastric plexus, which is approximately at the level of the promontory. The plexus is covered with a thin layer of connective tissue and fat. The plexus then divides to form hypogastric nerves. The right and left hypogastric nerves run within the space between visceral pelvic fascia of the mesorectum and parietal pelvic fascia of the pelvic wall. The dissection has to proceed in the posterior plane between those two fascias. When the plane is identified correctly, the dissection goes through an avascular areolar space. It can be performed with the help of a waterjet device, electrocautery or sharp scissors. Blunt finger preparation should be avoided. Dissection in the posterior plane usually does not create any problem and can easily be continued till the tip of the coccyx (till the pelvic floor). Posterior dissection should be extended laterally. Dorsolateral dissection usually mobilises the rectum sufficiently to pull it out of the pelvis to some extent but it remains fixed to the pelvic wall on both sides laterally. Standard technique of LAR involves ligation of the lateral ligaments of the rectum; these structures are however small nerve branches and minor vessels arising from the branches of the internal iliac artery, which pass to the mesorectum through inferior hypogastric plexus. Preparation in the right plane and proper use of diathermy should eliminate bleeding from those structures. The "lateral ligaments" should not be clamped and ligated. When the lateral and posterior dissections are complete, the attempt should be made to start the anterior part. This is the most difficult part of the surgical procedure. Anterior rectal wall, posterior wall of the bladder, the prostate and semi-
nal vesicles or the posterior wall of the vagina originate from the same embryonic tissue, therefore there is no clear plane separating these structures. The peritoneum over the retrouterine or rectovesical pouch should be divided. In the male the anterior wall of the rectum is covered with the 0.5-1-cm layer of mesorectum, therefore incision of the peritoneal reflection should be done over the bladder in order to avoid entering the mesorectum. Great care has to be taken laterally dissecting the Denonvillier's fascia where the inferior hypogastric plexus gives rise to the neurovascular bundle of Walsh which runs along the posterolateral aspect of the prostate. In the female the mesorectum is often very thin and therefore in direct contact with the posterior wall of the vagina. The crucial part of this part of the procedure is careful separation of the structures preferably with diathermy or water-jet in the plane between the Denonvillier's fascia and seminal vesicles in male and posterior wall of the vagina in females. The dissection behind the fascia should be natural continuation of the lateral dissection.
Following complete mobilisation of the rectum including mesorectum-free distal part of the intestine, the linear stapler is used to divide the rectum. Some Authors advocate the double-stapling technique.
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