Robotic LAR Basic surgical anatomy

As you know, the main goal of the surgical treatment for rectal cancer is to remove the rectal cancer with the regional lymph nose, which enveloped with mesorectal fascia. It guarantees good oncology outcome. In addition to that, we also pay attention to preserve the pelvic autonomic nervous system, which is crucial for the preservation of the breeding and sexual function. To complete this course, we must understand the basic anatomy of the rectum and related pelvic pressure.

In this slide, left-side figure shows that the actual section of the rectum with the rectal cancer. You can see the well-visualized collagen-fiber fascia wrapped the mesorectum. During the deep-pelvic dissection, any damage to the mesorectal fascia should it be avoided. If a breaching of the mesorectal fascia happened with improper dissection plan due to many reasons, such as the surgeon’s factor or a patient factor, risk of local recurrence will occur.

On the right side of the slide, you can see the kimbob, one of the famous Korean street foods. This seaweed-wrapped rice, and vegetable, and other favorite foodstuffs– if the enough foodstuff is close to seaweed wrap, it will be called a threat in the CRM.

The quality of the TME specimen is very important. As you can see, the left side of the specimen is toward the anus. Abundant mesorectum’s covered by shiny– mesorectal fascia was noted. It can be called as complete TME. No mesorectum defect was noted.

In summary of the TME with the pelvic autonomic-nerve preservation, first of all, sharp dissection must be kept at the deep pelvis. Be careful not to breach the mesorectal fascia with blunt dissection. Secondly, you should get a negative distal and circumference of resection margin. An appropriate distal mesorectum is removed. After proper sharp pelvic dissection along the fascia plane, we can subsequently preserve the pelvic autonomic nervous system.

On this sagittal view of the pelvis. you can see the name– fascia of the pelvis. For example, lateral proper fascia, Denonvillier’s fascia, presacral fascia, and the rectosacral fascia. In other words, what is fascia?

One cadaveric pelvis study, posterior side of the pelvis, left side of these showed Waldeyer fascia at the S4 level between the presacral and the rectal proper fascia. The presacral vein was covered with the presacral fascia.

That’s a presacral fascia connected with the rectal proper fascia by Waldeyer fascia. Unless this fascia is divided sharply avulsion injury of the presacral fascia and subsequent profuse presacral bleeding, bleeding occurs. Therefore, during the posterior pelvic dissection, its identification and a sharp division are important. After Waldeyer fascia divided, posterior dissection continued to proceed at the coccyx level.

After the peritoneal refraction was opened, anterior mobilization of the rectum is important, especially for pelvic autonomic nerve preservation. Usually, anterior dissection meets the anterior major rectum and the white tissue-membrane structure near the seminal vesicle.

After seminal vesicle was retracted upward, we can more clearly identify the Denonvillier’s fascia. As you can see in this photo, based on the cadaveric study, microcytic study, and histological study, it shows that Denonvillier’s fascia is attached to the prostate gland. To my knowledge and experience, anterior dissection is kept along posterior to the Denonvillier’s fascia. That is still a safe way to preserve the neurological bundle, which is going to run to the genitalia.

Regarding the difficulty of TME at the narrow pelvic cavity, real difficult to begin at the level of the true pelvic in the liver. The most challenging issues are concave limited space and space buried according to the individual characteristics, such as bony parameter, sex, shape, and angle of the pelvic floor. Below this level, the mesorectal fascia is attached to many fascias and organs in the narrow space.

In summary, it is important to remind ourselves a couple of issues during the TME at deep pelvic cavity– two extra TME pelvic-fascia layers, anterior and posterior dissection, running dissection and covering fascia with a pelvic autonomic nervous system, inferior hypogastric nerve, and the pelvic praxis, and neurovascular bundle. As you can see on cadaveric hemipelvis photo, a covering, thin parietal fascia, was removed, and the autonomic nervous system was exposed.

You can see the y-shaped autonomic nervous system was well visualized. You can see the inferior hypogastric nerve, pelvic plexus on right and the left in the neurovascular bundle. And the 6 o’clock direction is pelvic plexus. It’s forming by sacral parasympathetic nerve from the sacral foramen. So that is what we call the “pelvic plexus.”

At the level near the prostate gland, we must understand the relation between the Denonvillier’s fascia and the neurovascular bundle. At this level, usually, dense attachment to the prostrate – so if you plan to complete this comprehensive mobilization of the rectum to the level of the pelvic floor, posterior dissection to the Denonvillier’s fascia is maintained until dissection reaches to the perineal body beyond the prostate gland.

At the seminal-vesicle level, 10:00 and 2:00 direction– neurovascular bundle is located. This neurovascular bundle covered by one of the DVF layers. This known structure is also emerging from the pelvic plexus To my knowledge, one of the Denonvillier’s fascia covering the neurovascular bundle. Its continued to the parietal pelvic fascia.

At the prostate gland levels, as you know, the mesorectum is a nearly absent. So rectum are attached to the Denonvillier’s fascia and prostate gland. As you can see, the neurovascular bundle’s also located in 10 and 2 o’clock direction covered by Denonvillier’s fascia. Most of cases, a dissection’s easily done between the Denonvillier’s fascia and the rectum. And they can go to the level of the perineal body. Right-side figures– each H-E stained histology studies show that the neurovascular bundle’s located at the periphery of the prostate gland.

At the deep anterior and posterior mobilization of the rectum, the lateral part of the rectum is mobilized. Previously so-called “lateral ligament of the rectum,” lateral fixing point after deep anterior and posterior dissection of the rectum. It doesn’t prevent mobilization of rectum from the pelvic cavity.

With the anatomic exploration of the part and development of the MIS surgical technique for rectal cancer, we understand its attachment more. It is just composed of adhesion between the mesorectal fascia and the parietal fascia covering the plexus fractures.

Furthermore, middle rectal artery at this level rarely present and its lumen size usually small. With a precise and delicate dissection in this area, we can easily control this vessel if it is present. Too much attraction and mass ligation at this part results in damage of the pelvic plexus.

In the left portal, middle rectal arteries were visualized, and Denonvillier’s fascia and pelvic floors were. And right-side portal showed that the relation between the mesorectal fascia and pelvic plexus at the lateral part of the deep pelvic dissection.

Here, I would like to summarize my step-by-step approach to TME and pelvic autonomy node preservation. I called it “rainbow methos” because it’s composed of seven steps. Incision of the peritoneal pelvic peritoneum and identify the ureter and common iliac vessel as a landmark, and second, in posterior dissection to identify the inferior hypogastric nerve. Usually, this plan is avascular plan.

And next, the dissection changing the anterior dissection– after the peritoneum opened in dissection, and then we can easily identify the seminal vesicle and the Denonvillier’s fascia. And the next step is to, again, the deep posterior dissection. After we divide Waldeyer’s fascia and dissection going to the coccyx level, and then with changing to antero-lateral dissection.

A deep antero-lateral dissection– usually, in this step, we can identify the neurovascular bundle at the 10 or 2 o’clock and the seminal vesicle, and then push back to not damage it. And then we’re changing to deep postero-lateral dissection. And then usually, after we mobilize the posterior and anterior fully, lateral attachment of rectum to the pelvic wall– actually, pelvic plexus– that is what we call the “postero-lateral dissection.” It’s very important to preserve the pelvic plexus and carefully managed the midrectal artery if it is present.

And then lastly, we must identify the pelvic floor, including the puborectalis muscles and the pelvic-floor muscle. And then we can recognize– we can mobilize the rectum and mesorectum fully from the pelvic floor and the surrounding fascial structures.

Based on my experience and knowledge, step-by-step pelvic dissection with exact knowledge of the pelvic anatomy– that will be a royal road to the optimal method for good oncology and functional outcomes. I would like to re-emphasize a couple of steps during the procedures and show a summary of the Rainbow method.

Thank you very much.