Summary of laparoscopic-assisted radical anterior resection for rectal cancer
1. How to find the Toldt gap?
2. Treatment of submesenteric vessels
3. Separation of dorsal rectal mesentery
4. Separation of the lateral ligament
5. Separation of anterior Denonvillier’s fascia
6. Protection of the autonomic nerve
7. Dissection of distal rectal tumor
8. Intraoperative management of unexpected situations
1. How to find the Toldt gap under laparoscopy?
The key first step of laparoscopic TME is to find the Toldt gap, and once the Toldt gap is found, the subsequent operation will be smooth. The assistant lifts the sigmoid colon toward the ceiling, and at this point, a “groove” can be seen between the right side of the sigmoid colon and the retroperitoneum, and the retroperitoneum can be cut at the iliac capsule in this groove to find the yellow-white loose Toldt space that can be seen here. These two fascia are actually one level, and the ureter is below the prerenal fascia, so it will not be damaged.
2. Treatment of submesenteric vessels
After opening the toldt fascia on the medial side of the sigmoid colon, the root of the inferior mesenteric artery will be found by walking upward along the anterior abdominal aortic fascia, pulling the sigmoid colon toward the ceiling, making the root of the inferior mesenteric artery form a triangle with the abdominal aorta, separating the lymphatic fatty tissue around the arterial vessels, and skeletonizing the IMA. After dealing with the arterial vessels, the inferior mesenteric vein on the left side of the arterial vessels is treated, noting that the directions of the inferior mesenteric artery and the inferior mesenteric vein are not the same, as the IMA emanates from the abdominal aorta, while the IMV converges into the splenic vein.
3.Separation of dorsal rectal mesentery
After dealing with the mesenteric vessels, then turn back down and separate the rectum, the most critical thing in rectal cancer surgery is how to achieve rectal mesenteric resection. The dorsal rectum (that is, the posterior mesentery) is separated first, and at this time, attention should be paid to the protection of the inferior ventral nerve, which is white under the laparoscope and easy to identify, whether the inferior ventral nerve is inside or outside the rectal mesentery is still debated, and we see in the clinic that the inferior ventral nerve is close to the mesentery, and after finding the toldt gap, attention should be paid to the identification of the inferior ventral nerve for protection.
It is best to tunnel between the mural and visceral mesentery to the deepest point, reaching the tip of the coccyx. The right ureter is easily identified laparoscopically, while the left ureter is behind the anterior fascial membrane and is sometimes peristaltic, which is also easily identified. Note: At this time, a small piece of gauze can be placed on the dorsal side of the rectal mesentery where the medial sigmoid colon is well freed, so that the level can be easily identified when the left side of the sigmoid colon is freed, and it is easy to meet the division and avoid too deep separation. Open the physiological adhesions between the left side of the sigmoid colon and the lateral abdominal wall, and gradually separate downward along the arc of the pelvic wall to the lateral side of the rectum.
4. Separation of the lateral ligaments
Separation of the lateral mesentery (also known as the lateral ligament) points: pay attention to the eyes looking directly in front of the rectum, along the arc of the pelvic wall downward separation, especially careful not to be too close to the rectum and go inside the rectal mesentery, once inside the rectal mesentery there will be bleeding, the anatomy is not clear, so the operator must be familiar with the anatomical structure of the lateral rectum. Here again, do not treat the lateral ligaments too close to the pelvic wall! Too close to the pelvic wall makes it easy to injure the inferior abdominal plexus. Postoperatively, patients will have sexual impairment and difficulty in urination.
The lateral ligament of the rectum is a surgical term, there is no such structure in anatomy. You can read this book for a detailed explanation. In the lateral separation is to pay attention to the curvature along the pelvic wall, a little distance from the pelvic wall is best, the lateral ligament here is slightly close to the rectal side, which helps to protect the pelvic visceral nerves, which can actually be clearly seen laparoscopically, pay attention to the protection of the pelvic visceral nerves.
5. Separation of Denonvillier’s fascia in front
At 1cm-2cm above the retroperitoneal fold, the peritoneum is incised for anterior rectal freeing. If the cancer is located in the anterior rectal wall, it is freeing in front of Denonvilliers fascia, and if the cancer is located in the posterior rectal wall, it can be freeing behind Denonvilliers fascia. In men, the freeing is done to the tip of the prostate. In female patients, the uterus can be suspended first so as not to interfere with the surgical field of view, and the assistant can be asked to put his fingers into the vaginal guide so as not to split the vagina, and women can try to free down to the puborectalis muscle. Zhang Ce mentioned ……… that in our clinical practice, we found that it was more difficult to separate between the two layers of Denonvillier’s fascia. It is relatively easy to separate before Denonvillier’s fascia. At this stage, special attention is paid to avoid damaging the neurovascular bundle (walsh bundle) behind the prostate.
6. Protection of the autonomic nerve
The protection of the autonomic nerves includes the abdominal aortic plexus, the superior inferior abdominal plexus, the inferior abdominal nerve, and the inferior inferior abdominal plexus. The abdominal aortic plexus is on the surface of the abdominal aorta, and because it has a skylight at the root of the inferior mesenteric artery, it should not be damaged. It is easier to damage the inferior abdominal plexus of the inferior nerve nucleus, and the protection of the inferior abdominal nerve has been mentioned earlier and will not be repeated. The inferior abdominal plexus is the pelvic visceral nerve that emanates from the 2, 3, and 4 sacral foramina together with the inferior abdominal nerve that can be seen laparoscopically, and in separating the rectal When separating the rectum laterally, pay attention to the curvature of the pelvis and free it near the rectum side to avoid damaging the neurovascular bundle (walsh bundle) behind the prostate
7. Separation of distal rectal tumor
After separating the lateral ligament, the superior anal raphe is below, how to make sure the rectal mesentery is in place? After the separation of rectal mesentery is in place, we should be able to see the anal raphe, where we can see that the rectum is obviously thinned into the anal raphe fissure, and only here is the complete rectal mesorectal resection. How to determine the distal resection margin of rectal cancer? At present, there are generally four methods.
1.Visual inspection method, for tumors that are relatively large and invade into the plasma layer, and can be seen under laparoscopy, it is easier to determine the distal cutting edge.
2.Intraoperative contact colonoscopy. For tumors above 7cm in the rectum, if the tumor cannot be seen directly under laparoscopy, it is a good way to contact colonoscopy in time and determine the incision margin through colonoscopy guidance.
3.Reverse torus out of the anus to determine the incision margin. After cutting off the mesenteric vessels at the root of the inferior mesenteric artery, freeing the sigmoid colon and the upper end of the rectum, transecting the intestinal canal at the upper end of the rectum or the lower part of the sigmoid colon, completely freeing the rectum to the plane of the anal raphe below the tumor through the abdomen, cutting the anal caudal ligament, freeing the rectum to the junction of the rectum and the anal canal. (The caudal ligament is a membranous structure between the caudal bone and the anal canal after dealing with the rectosacral ligament, which can be revealed more clearly by laparoscopic surgery.) After sufficient freeing, the top of the rectal stump can be clamped with long tissue forceps, and the intestinal canal together with the mesentery can be completely dragged out from the anus through the rectal cavity, and the intestinal canal can be closed and cut off with a closure device at a suitable site between the tumor and the dentate line, and a tubular anastomosis can be performed with the proximal end of the intestinal canal through the closure line. A tubular anastomosis is performed with the proximal intestine through the closure line.
For middle and lower rectal cancer, we commonly use the third method to determine the incision margin, which is less expensive compared with laparoscopic Endo-GIA or Endo-CUT, and the operation is reliable, and insufficient incision margin will not occur. However, for T4 tumors, tumors that are too large and invade more than half circle of the rectum cannot be back-dragged out of the anus.
8, Treatment of intraoperative accidents
The following accidents are common in laparoscopic TME surgery: 1) bleeding from the submesenteric artery; 2) not recognizing the level and entering inside the mesentery when free; 3) bleeding from the presacral area; 4) not stapling the severed end when cutting the distal rectum.
1) Bleeding from the inferior mesenteric artery. When freeing the inferior mesenteric artery, do not get too close to the root, as there is now literature showing that rectal cancer surgery does not require root ligation of mesenteric vessels. Once the vessel is accidentally split during the separation of IMA, the left hand clamp should be immediately clamped on the proximal end of IMA, and if there is enough distance on the vessel at the end of the heart, hemo-lock can be applied, if the distance is not enough, the hemorrhage should be immediately stopped by turning on the abdomen.
2) Failure to recognize the level of rectal mesentery and enter inside the mesentery during freeing. This happens in two cases, one is not to find a more lax Toldt gap here at the sacral headland at the beginning of surgery, especially in too fat and too thin patients who cannot find the level easily. Patience and familiarity with the anatomical levels of the surgery are required. Another easy place to get inside the tether is when dealing with the lateral tether, where the surgeon fears damaging the pelvic wall and separating too far medially. It is important to handle this area with the eye focused on the anterior rectal wall directly below to see the curvature of the pelvic wall.
3) Anterior sacral hemorrhage. Anterior sacral hemorrhage is rare, and no anterior sacral hemorrhage was encountered in this group. Anterior sacral hemorrhage is rarely reported because the wall fascia and waldeyer’s fascia can be seen very clearly under laparoscopy due to the magnification effect of the laparoscope. Once it occurs, the abdomen should be opened immediately by intermediate transfer.
4) When cutting the distal rectum, the severed end is not stapled. This is not uncommon in laparoscopic rectal cancer surgery, and at the slightest occurrence, the distal rectum cannot be stapled again due to its short length, and the surgeon may panic. We encountered 3 cases of this situation. Treatment methods.
1, if the distal rectum is very close to the anus, less than 4 cm, the severed end can be dragged out via the anus with tissue forceps, then intermittently sutured, and then anastomosed with a tubular anastomosis;
2. If the distal rectal end is far from the anus, the severed end can be intermittently sutured under laparoscopy and then anastomosed with a tubular anastomosis. After the above treatment, a prophylactic ileostomy is performed at the end of the ileum.
Rectal back-dragging out of the anus
anterior sacral space
anterior renal fascia
inferior hypogastric nerve
Visceral pelvic nerve
Denonvilliers fascia
Recto-anal junction