Although there is controversy on the existence of lateral ligament, the lateral bundle structure must be treated in the operation of rectectomy. In order to avoid injuring of the lateral pelvic plexus, sharp disconnection should be carried out by electric knife, and disconnection should be achieved near the rectum under the condition that the structure is maintained. There may be arteriae rectalis caudalis in the lateral ligament, but ultrasonic knife or electric coagulation can usually seal them, and clamping or ligation is not necessary; this is very important to maintain the completeness of the lateral side of the mesorectum.

In traditional opinion of therapy against colon cancer, high ligation should be carried out to the inferior mesenteric artery. Classical high ligation means that the main trunk of the inferior mesenteric artery should be ligated and disconnected 2 cm away from aorta abdominalis at the root of the inferior mesenteric artery. However, in recent years, more and more findings of evidence-based medicine indicated that high ligation does not improve the prognosis of patients; instead, it may lead to complications such as ischemic necrosis [15]. Therefore, NCCN guide recommends that, if intraoperative exploration finds there is no swollen lymph node at the root of the mesentery, routine high cleaning and ligation are not necessary; instead, ligation of the root of the superior rectal artery is enough; a part of branches of blood vessels in the sigmoid colon may be ligated selectively according to the intraoperative colon tension.

Arteriae rectalis caudalis, coming from the internal pudendal artery or internal iliac artery, is a small artery distributed at the lateral side of middle and lower segments of the rectum, of which the diameter is about 1–2 mm with a big anatomic variation. It is reported that the possibility of occurrence of arteriae rectalis caudalis is 22–100 % [14, 16, 17]. If it is found in operation, this blood vessel can be disconnected and coagulated with electric knife, while clamping and ligation are not necessary.

Presacral venous plexus is a structure of blood vessels in front of the sacral periosteum, consisting of two big lateral sacral veins and one median sacral vein. Presacral venous hemorrhage is a severe and dangerous intraoperative event during separation of posterior of the rectum, especially Waldeyer’s fascia, of which the anatomic background is that the presacral venous plexus will retract to sacral foramen after breakage [18]. Therefore, during presacral venous hemorrhage, clamping and ligation cannot stop hemorrhage; moreover, it may tear presacral vein and aggravate hemorrhage. At present, there are two hemostatic methods in clinic: (1) Resect a piece of rectus abdominis, of which the diameter is 2 cm, press it on the bleeding point, and carry out electric coagulation (recommended electric coagulation value >100); then the charring of muscle will coagulate the contacted venous plexus [19] (Fig. 10.6); (2) press a tailor-made thumb pin on the bleeding point, penetrate the venous plexus, and stabilize it in the sacrum; with the help of local pressing, the purpose of hemostasis is achieved; it should be noted that the distance between the midline of the sacrum and the point where the thumb pin is pressing in should be less than 2 cm at S1 level, while at S5 level, it should be less than 1 cm, in order to avoid damaging the lateral sacral nervous plexus [20].

In rectal surgery, especially radical resection of rectal cancer, the pelvic nerve structure should be protected as much as possible, in order to ensure that the patient can get good urinary and sexual function. In TME surgery, attention should be paid to the following: (1) After opening the lateral peritoneum at the inner side of the ureter, before entering the “holy plane,” attention must be paid to the dissociation and protection of hypogastric nerve at both sides. If dissociation is carried out directly along the loose gap that appears first, the hypogastric nerve would usually be disconnected at the posterior-lateral side of the rectum. Therefore, after the appearance of the gap, one should find the starting site of two hypogastric nerves from superior hypogastric nerve in front of sacropromontory (note the nerve trunk at this part is usually thick), sharply dissociate the main trunk of hypogastric nerve from the back of the mesorectum until the place where it enters the lateral pelvic wall to form the pelvic plexus, and then carry out the successive operation of TME. (2) Disconnection of the lateral ligament should be carried out adjacent to the rectum, in order to avoid injuring the pelvic plexus. (3) During the traction and dissociation of the sigmoid mesocolon to the branch of aorta abdominalis, the starting part of the hypogastric nerve at the left side is usually tracked together; at this time, the hypogastric nerve at the left side should not be injured [21].

In recent years, according to the finding of evidence-based medicine, lateral lymph node metastasis indicated a worse prognosis, while lateral lymph node dissection increased the postoperative injury to urinary and sexual function significantly and could not improve the survival rate of patients [22]. Especially, as application of neoadjuvant preoperative radiotherapy can lower the local incidence after operation, some researches indicate that lateral dissection after preoperative radiotherapy has no significant meaning [23]. Therefore, lateral disconnection can act as optional operation at present; during the operation, if lateral swollen lymph nodes are contacted, they should be disconnected.

In order to judge the possibility of anus-preserving operation, surgeons usually carry out digital examination of the rectum to explore the position of tumor; the distance between the lower margin of tumor and the surgical anal tube is a factor to decide whether or not the anus can be preserved. If this distance is less than 1 cm, a distal margin with pathological negative is hard to obtain during operation; thus, the risk of local recurrence after anus preservation is increased significantly. The distance between the tumor and the dentate line (or the anatomical anal tube) has a less important meaning in guiding surgery operation.

In 1908, Miles brought forward the conception of APR according to the achievements of study on lymph drainage of rectal cancer, which lowered the postoperative local recurrence rate of middle or lower rectal cancer significantly. In recent 70 years, APR operation was always the standard operation for lower rectal cancer [24]. With the development of concept and skill of TME, more and more colorectal surgeons care about the whole dissociation of the mesorectum, other than stress on the resection range of levator ani muscle and fat tissues in ischiorectal fossa. With the development of pathology of rectal cancer and image technology, more and more attention have been paid to the question how to ensure to get a negative circumferential resection margin (CRM) after radical resection of rectal cancer [25]. The study of evidence-based medicine also indicated that APR operation has a worse prognosis than the anus-preserving LAR operation, because of the higher rate of positive CRM after APR operation, which may lead to local recurrence [26]. Therefore, on the basis of TME, the cylindrical APR operation, in which the resection range of levator ani muscle is extended, has attracted attention of colorectal surgeons gradually [27].

Because of the development of lower stapling technique, a distance <6 cm from the lower margin of tumor to the edge of the anus is no longer the absolute indication of APR operation. We suggest that the common indication is the rectal cancer, of which the distance between tumor and the anus is less than 5 cm. Application of APR needs correct preoperative staging, good operation, and cautious intraoperative decision.

The following conditions were often met: (1) Preoperative MRI judged that the tumor had invaded levator ani muscle, or digital examination of the anus indicated that the distance between tumor and upper edge of surgical anal tube was less than 1 cm. (2) During operation, pelvic canal stenosis or giant tumor was founded; thus, the lower rectum was difficult to be dissociated and stapled. (3) After sufficient dissociation of the rectum, satisfactory distal incisal margin (>1 cm) was not yet obtained, or rapid pathological examination indicated a positive recisal margin. (4) After local resection of early lower rectal cancer, pathological examination indicated a positive incisal margin or a lesion over T2 stage.

As APR operation has a large resection range and will take a long time, general anesthesia should be used. Lithotomy position should be adopted to reveal perineum. It should be noted that (1) after anesthesia, the operation table can be adjusted so that the head is in a lower position and the feet are in a higher position; thus, the small intestine will be set at the front of surgery field; (2) the coccyx of patients should be extruded, and the angle between thighs and trunk should be less than 90°, so that the perineal region can be revealed enough to facilitate operation; (3) during the setting of lithotomy position, the position of patient’s leg should be adjusted to avoid pressing the common peroneal nerve. The incision is usually selected at the center of the abdomen around the navel, of which the bottom should reach the pubic symphysis and the top boundary depends on the condition of the patient. During the incision of abdominal wall to the lower part, avoid injure bladder. For female patients, womb can be suspended to facilitate revealing.

After entry of the abdomen, explore whether or not there is ascites, hepatic metastasis, or peritoneal metastasis and collect information of abdominal visceral organ such as the colon and stomach; explore whether or not there are swollen lymph nodes at the root of the inferior mesenteric artery, in front of aorta abdominalis, or at the area of iliac vessels; for female, attention should be paid to the bilateral ovary. Finally, explore the tumor and pay attention to the dissociation degree of the tumor and the relation of the tumor to adjacent organs and pelvic wall; during operation, preoperative pelvic MRI image should be combined to identify the local condition of tumor.

After complete exploration, the operation table can be adjusted so that the head is in a lower position and the feet are in a higher position; push the small intestine to the side of the head. Ligate the intestinal canal with tape at the boundary of the rectum and sigmoid colon above the tumor. Tract the tape so that the sigmoid mesocolon has a certain stress, touch to identify the direction of superior rectal artery and sigmoid arteries, open the peritoneum at the surface of the mesentery, and preligate at the root of superior rectal artery. For patient who has a shorter length of sigmoid colon, a narrow pelvic cavity, or an overweight body, under the precondition that the proximal end of the rectum is long enough to be brought out of abdominal wall, the rectum-sigmoid colon can be disconnected with an occluder; thus, traction and dissociation of proximal end of the rectum are helpful for revealing the posterior rectal wall.