Rectal cancer surgery (anterior resection or low anterior resection)
I. Relevant anatomy.
Measured from the anal verge, the rectum is generally 12cm-15cm. the rectum is closely attached to the sacral recess and divided into the upper, middle and lower 1/3. generally the upper 1/3-1/2 is covered by the peritoneum. The rectum can be lengthened about 3cm-5cm after complete free uplifting, especially the tumor located in the posterior wall of the rectum is lengthened obviously, and the tumor located in the anterior wall of the rectum is not lengthened obviously. In men, the anal verge is 7cm-8cm from the peritoneal reflex, and in women, it is 6cm-7cm from the peritoneal reflex.
The middle 1/3 is 5cm-10cm above the puborectalis muscle, and the upper 1/3 is 10cm-15cm above the puborectalis muscle.
1. Rectal mesentery.
The non-true tract is the posterior rectal fat and lymphatic tissue encircled by the visceral layer of fascia in the pelvic cavity. There is a loose gap between the wall fascia (presacral fascia) and the dirty fascia (called “holy plane” sacred interface), and at the S3 or S4 level, the dirty fascia and wall fascia fuse to form the rectosacral ligament (or rectosacral fascia).
2. Nerves.
At the bifurcation of the abdominal aorta there is the superior inferior abdominal plexus, at the sacral promontory there are left and right inferior abdominal nerve trunks, and in the lateral pelvic wall there is the pelvic plexus composed of sympathetic and parasympathetic nerves together.
3.Blood flow.
The rectum is supplied by the superior rectal artery, the middle rectal artery (from the internal iliac artery), and the inferior rectal artery (from the internal pubic artery), which are divided from the inferior mesenteric artery. The left hemicocele is supplied by the left branch of the transverse colic artery (from the superior mesenteric artery) and the inferior mesenteric artery, and the colon is connected to the inferior mesenteric artery by the marginal artery of Drummond, except for a few “watersheds” in the splenic flexure of the colon that lack a marginal artery. Care should be taken after ligation of the inferior mesenteric artery at the root.
Anterior resection means resection of the proximal rectum (e.g., upper 1/3 of the rectum) and anastomosis between the colon and the intraperitoneal rectum, with the anastomosis located on the retroperitoneal fold.
Low anterior resection means resection: it means resection of the distal rectum (such as middle 1/3 rectum, lower 1/3 rectum) and anastomosis between the colon and the extraperitoneal rectum with the anastomosis located under the peritoneal reflex.
Ultra-low anterior resection: refers to the resection of the distal rectum, and the anastomosis between the colon and the anal canal is performed. It is possible to perform colonic J-pouch anastomosis. J-pouch is generally 6 cm long.
Second, the specific steps
1.After the completion of intravenous complex anesthesia with tracheal intubation, take the truncated position with low head and high feet (Trendelenburg position). Place the gastric tube and urinary catheter separately, routinely disinfect the skin of the abdominal surgical area and perineum, and lay the towel. Generally the operator is on the left side, the first assistant is on the right side, and the second group of hands is between the patient’s legs.
2, incision, exploration: generally take the pubic bone to the umbilicus of the lower abdomen median incision, or paramedian incision or trans-rectus abdominis incision, according to the specific intraoperative situation can be extended upward. After incision, the tumor is explored according to the principle of distant and near, focusing on the liver, peritoneum, pelvis, root of the inferior mesenteric artery, abdominal aorta, ovaries (female), etc. for metastasis. Finally, the tumor was gently explored.
3.Sigmoid colon free: After the exploration, the abdominal cavity was drawn open with the automatic abdominal pulling hook, and the small intestine was drawn toward the right upper abdomen with the wet gauze pad. The assistant pulled the sigmoid colon forward to the right, and after the electric knife cut the congenital adhesion between the sigmoid mesentery and the lateral peritoneum, the white line of Toldt’s fascia was cut, and the left posterior peritoneum of the rectum was cut to the pelvic cavity to the vicinity of the peritoneal reflex, and the sigmoid colon was further pulled to the right and forward, and the spermatic cord (testicular) vessels or ovarian vessels were easily found at the iliac vessels, and the left ureter was found at the inner side of the vessels (reproductive vessels and ureter were in the As long as the sigmoid colon is free on the superficial side of Toldt’s fascia, damage to the genital vessels and ureter can be avoided). At this point, the sigmoid colon is pulled to the right and forward to separate the soft tissue between the superior rectal artery and the pelvic wall fascia. When the sigmoid mesentery is free to the middle of the abdominal cavity or the abdominal aorta, the operator spreads and pulls the sigmoid colon and its mesentery to the left and forward, places the left hand behind the free sigmoid mesentery and superior rectal artery as a guide to protect it, and incises the right side of the sigmoid mesentery and the right posterior peritoneum of the rectum to the pelvic cavity near the peritoneal reflex. The peritoneum of the sigmoid colon was incised upward to the root of the inferior mesenteric artery, taking care not to damage the nerves at the root of the inferior mesenteric artery. Depending on the situation, ligation of the root of the inferior mesenteric artery or ligation of the left colonic artery at the division, or ligation of the root of the superior rectal artery is possible. In order to move the descending colon down and make the anastomosis tension-free, most ligations are performed at the root of the inferior mesenteric artery, and whether the vessel is ligated in a high or low position has no effect on survival. Do not damage the left ureter during root ligation because it is 1 cm to the left of the tip of the inferior mesenteric artery vessel, which is close to the vessel tip and should not be damaged.
Be careful not to enter the anterior sacral space for freeing without severing the sigmoid colon.
The location of the colon to be dissected is decided according to the situation. Generally, the middle and lower sigmoid colon are dissected, the upper sigmoid colon is preserved (or the junction of descending colon and sigmoid colon is dissected), and the mesentery is cut to the location of the colon to be dissected. At this point, the colon is not dissected for the time being. The next step is to free the descending colon.
Indicate the location of the dissociated vessels, and keep the colon as far down the length as possible; the marginal vessels are present in almost everyone, and keeping the marginal vessels intact will maintain blood flow to the distal colon.
4, descending colon and splenic flexure free: a common mistake during freeing is to free upward along the Toldt white line to the spleen. Pull the descending colon inward and forward with force, start freeing upward along the Toldt white line, and gradually free medially, find Gerota’s fascia at the left kidney, free the colon on its superficial side, do not free on its deep side, the deep side of Gerota’s fascia is prerenal fat. Usually free the colon immediately, cut the diaphragmatic colonic ligament, splenic colonic ligament, and the gastrocolic ligament (greater omentum) of the distal transverse colon, and at this time the inferior mesenteric vein can be cut at the inferior margin of the pancreas to further make the colon easy to move down. When freeing the descending colon and splenic flexure, it is more convenient for the operator to switch to the right side and pay attention not to damage the spleen, and extend the incision upward for freeing if necessary.
5.Severing the sigmoid colon: decide the severing line of the sigmoid colon according to the specific situation, and sever the sigmoid colon mesentery to the intended severing place. Cut off the colon with a purse-string clamp, place the anvil of the tubular anastomosis proximally, and ligate the distal end after sterilization.
6.Posterior rectal freeing: pull forward and downward (to the foot side) the sigmoid colon and rectum, and the assistant gently press down the fascia at the sacral promontory, where the inferior ventral nerve is at the deep surface of the presacral fascia, separate the loose tissue between the rectal mesentery and the presacral fascia with scissors or electric knife, start to enter the presacral space at the sacral promontory, and free downward with long curved scissors or electric knife under direct vision along the recess of the sacrum, and pull with St. Marks pulling hook The rectum is easily revealed and freed.
The rectosacral ligament (or rectosacral fascia) is encountered at the S3-S4 sacrum; this ligament should not be separated bluntly by hand or it will easily tear the anterior sacral venous plexus for hemorrhage. It should be separated sharply with an electric knife or scissors under direct vision, and the anterior sacral space should be further opened after cutting the ligament, and then further separated downward over the tip of the coccyx to the levator muscle. The posterior rectum should be separated as far as possible when separating the posterior lateral rectum. The rectosacral ligament is easily separated by placing the patient flat or in the Trendelenburg position (head high and foot low). Take care not to damage the anterior sacral nerve (parasympathetic nerve) that emanates from the sacral foramen. When separating the posterior lateral rectum forward, use closed scissors or a suction device to separate it by “rubbing and dipping”, so as not to easily damage the pelvic plexus.
7.Anterior rectal wall freeing: 1cm-2cm above the peritoneal fold, cut the peritoneum for anterior rectal freeing, if the cancer is located in the anterior rectal wall, it will be freeing in front of Denonvilliers fascia, if the cancer is located in the posterior rectal wall, it can be freeing behind Denonvilliers fascia. The bladder or uterus is retracted with a St. Marks hook, and the surgeon uses the left hand to retract the rectum backward and downward to reveal the gap between the anterior rectal wall and the seminal vesicles and prostate (for women, the gap between the anterior rectal wall and the posterior vaginal wall), at which point it is important to retract the St. Marks hook firmly upward and to the foot side. Free with the electric knife to the tip of the prostate in men and as far down as possible to the puborectalis muscle in women. Do not damage the seminal vesicles, prostate gland, or posterior vaginal wall.
8, free the lateral rectal ligament: the operator’s left hand pulls the rectum downward and inward, separates a hole in front of the lateral ligament, the middle finger of the left hand is inserted from the front to the back from the hole, the index finger is behind the lateral ligament, so that the lateral ligament is pulled medially, the assistant gently pulls the lateral pelvic wall laterally with the pull structure, cuts the medial lateral ligament with electrocoagulation, preserves the lateral pelvic wall without damage, so that the pelvic plexus that governs the reproductive system is not damaged and does not Postoperative sexual or ejaculatory dysfunction and/or urinary dysfunction occurs. That is, the lateral ligaments are cut as close to the rectum as possible while maintaining radical treatment. It is not advocated to add, cut and ligate the lateral ligaments in a large clamp, which can easily damage the nerves, and the rectal middle artery in the lateral ligaments can generally be hemostatic by electrocoagulation and does not require ligation.
9.Distal rectal cut: For upper 1/3 of rectum, it is not necessary to perform total rectal mesenteric excision (TME), and 5cm of distal rectum and mesentery is sufficient. For middle and lower rectal cancer, TME should be performed; after TME for middle and lower rectal cancer, the function of anal sphincter can be preserved, because the rectum can be lengthened by 3cm-5cm after complete freeing, especially for cancer located in the posterior wall of the rectum; for cancer located in the anterior wall, the lengthening is generally not as long as the posterior wall.
Flush the rectum with iodine solution or 0.1% Neosporin in order to kill the shed cancer cells.
The rectum and the mesentery should be cut off at right angles with the rectal mesentery and the rectum with the closing device (rotatable or non-rotatable type).
10.Anastomosis: perform anastomosis between rectum and sigmoid colon or descending colon. The anus is dilated by 4 fingers and anastomosed with a 31-gauge tubular anastomosis. Manual sutures can be performed, usually with a layer of interrupted sutures with No. 1 silk thread. Be careful not to damage the posterior vaginal wall or the seminal vesicles or prostate during the anastomosis.
After completion of the anastomosis, the anastomosis is checked for integrity by gas injection test or by colonoscopy. It is usually important to check the integrity of the two circles cut by the anastomosis.
The anastomosis is noted to have normal intestinal blood flow, the stump should have active bleeding, the anastomosis should not be tense, and the colon should be able to lie loosely and naturally in the presacral space.
The pelvic floor peritoneum can be sutured or left open without sutures. If sutured it should be sutured tightly and leave no holes. If open, it is left completely open.
One or two closed drains may be placed in the anterior sacral space. Routine placement of drains is advocated by some and not by others. Prophylactic transverse colonic or ileal fistulas are not usually routinely performed.
Hand sutures: posterior wall sutures are completely sutured and knotted together. Anterior wall internal return suture. The suture is closed with a No. 1 silk suture, and the suture spacing and stitch distance are 5 mm.
J-shaped storage pouch anastomosis (pouch length approximately 6 cm).
Coloanal anastomosis: anastomosis by clutch or manual anastomosis.
A cut the rectum at the anorectal ring, B remove the mucosa of the recto-anal canal stump by electrocoagulation peeling at the beginning of the anal dentate line, C,D perform colonic-anal canal anastomosis (anastomosis at the dentate line).
Postoperative management.
The gastric tube is not routinely left in place and is removed after anesthesia resuscitation. Anterior sacral closed drainage is usually removed in 4-5 days. If hundreds of milliliters of fluid are drained, laboratory tests are performed to see if there is a vesicoureteral or ureteral fistula. If there is an anastomotic fistula, keep the drainage open and treat conservatively if there is no peritonitis condition. Generally 50% of all leaks can be cured with drainage, reducing surgical treatment to a minimum. Urinary catheters are usually removed 5-6 days postoperatively. A liquid diet may be given for days 2-3, with gradual increase in volume and transition to a regular diet.
Postoperative bowel function may be problematic, and colonic clustered peristalsis may occur due to loss of nerve in the free colon and ligation of the inferior mesenteric artery. Frequent and urgent stools may be associated with anastomotic stricture, new rectal spasm and radiation therapy. Several months of administration of fibre supplements and anti-spasmodic drugs given before meals are required. If chemotherapy is completed, a low-fat, high-fiber diet is given. Anastomotic strictures caused by early anastomosis may be dilated with fingerprick 3-4 weeks postoperatively and monthly as needed. Persistent stenosis that occurs late may require endoluminal stenosis electrocoagulation shaping. A high fiber diet is required to keep the lumen dilated after stricture dilation.