Optimal Complete Rectum Mobilization Focused on the Anatomy of the Pelvic Fascia and Autonomic Nerves: 30 Years of Experience at Severance Hospital

Abstract

The primary goal of surgery for rectal cancer is to achieve an oncologically safe resection, i.e., a radical resection with a sufficient safe margin. Total mesorectal excision has been introduced for radical surgery of rectal cancer and has yielded greatly improved oncologic outcomes in terms of local recurrence and cancer-specific survival. Along with oncologic outcomes, functional outcomes, such as voiding and sexual function, have also been emphasized in patients undergoing rectal cancer surgery to improve quality of life. Intraoperative nerve damage or combined excision is the primary reason for sexual and urinary dysfunction. In the past, these forms of damage could be attributed to the lack of anatomical knowledge and poor visualization of the pelvic autonomic nerve. With the adoption of minimally invasive surgery, visualization of nerve structure and meticulous dissection for the mesorectum are now possible. As the leading hospital employing this technique, we have adopted minimally invasive platforms (laparoscopy, robot-assisted surgery) in the field of rectal cancer surgery and standardized this technique globally. Here, we review a standardized technique for rectal cancer surgery based on our experience at Severance Hospital, suggest some practical technical tips, and discuss a couple of debatable issues in this field.

Keywords: Total mesorectal excision; anatomy; rainbow technique; rectal cancer.

Fig. 1. The relationship between fascia around the rectum. The rectal proper fascia, the fascia covering the mesorectum, is also called visceral endopelvic fascia; the presacral fascia, the fascia covering the sacrum, is also called the parietal endopelvic fascia; Denonvilliers' fascia, a dense membrane between the rectum and the seminal vesicles, is also called the rectogenital fascia; Waldeyer's fascia is a dense connective tissue layer between the posterior part of the rectal proper fascia and the presacral fascia at the S3 and S4 levels. Adapted from Lee et al. Ann Coloproctol 2018;34(2):59–71.

Fig. 2. Y-shaped pelvic autonomic nerve structures seen in the hemipelvis of a cadaveric section. The inferior hypogastric nerve descends along each side of the pelvic wall and merges with the sacral parasympathetic nerves to become the pelvic plexus. This plexus is densely attached to the lateral part of the mesorectal fascia, and the NVBs extend to the genitalia. Adapted from Lee et al. Ann Coloproctol 2018;34(2):59–71. NVB, neurovascular bundle.

Fig. 3. Anatomy of the pelvic floor muscles. (A) The funnel-shaped pelvic floor with the sphincter complex after removal of the sacrum. Adapted from Lee et al. Ann Coloproctol 2018;34(2):59–71. (B) Gradual coning down of the pelvic floor with a wide angle usually seen in women. (C) Steep coning down of the pelvic floor with a narrow angle usually seen in men. (D) The mesorectum tapered out 2 or 3 cm proximally from the pelvic floor.

Fig. 4. Difficulty in operation in the deep pelvis. (A) Sagittal view of MRI shows the box line area, it is concave, deep, and narrow. (B) Achievement of complete TME without coning down of the mesorectum, especially in the deep pelvis, requires a standardized technique. The white square in each picture indicates the deep pelvis. TME, total mesorectal excision.

Fig. 5. Anterior dissection. (A) The anterior surface of the peritoneum is divided at the peritoneal reflection. (B) The seminal vesicle and DVF are landmark structures for anterior dissection. White arrows, DVF; white dotted line, optimal dissection plane. DVF, Denonvilliers' fascia.

Fig. 6. Schematic images of the usual dissection plane in the anterior dissection. Unless the tumor directly invades the seminal vesicle, dissection should be directed below the DVF. This is the optimal plane for preservation of nerves, and the dissection continues laterally along the seminal vesicles. (A) Axial view. (B) Sagittal view.

Fig. 7. Deep anterolateral dissection. (A) Deep anterolateral dissection begins from the previously incised DVF in the anterior dissection. (B) The dissection continues to the lateral side along the DVF. (C) The NVB can be exposed in the anterolateral side. (D) Schematic picture showing the dissection plane. White arrows, DVF; white dotted line, optimal dissection plane.

Fig. 8. Deep posterolateral dissection. (A) Dissection can be performed easily along the previous dissection line from a deep posterior dissection and deep anterolateral dissection. (B) With sequential dissection from deep anterolateral to the posterolateral last lateral attachment, the lateral side of the MRF is safely dissected from the pelvic plexus. White arrows: sequence of dissection. MRF, mesorectal fascia.

Fig. 9. Practical technical tips in the rainbow method. (A) Gentle counter-traction of the seminal vesicle in the 2 o'clock direction and the NVB allows entrance into the anterolateral portion of the lower rectum, which is the gate to the deep pelvic floor (white dotted line). (B) Deep-anterior dissection followed by deep-posterior dissection, and then, lateral attachment can yield complete TME without tearing and nerve damage. (C) Schematic picture showing the gate to the pelvic floor after deep anterolateral dissection. (D) Schematic picture showing the operation field after deep anterolateral and deep posterolateral dissection. TME, total meso-rectal excision.

Fig. 10. Customized excision of the DVF according to the tumor location and extent of tumor invasion. (A) Unless the tumor directly invades the seminal vesicle, dissection should be directed to below the DVF. (B) Dissection performed anteriorly is resorted to only in cases of anteriorly located tumors or in cases of a suspected or threatened circumferential resection margin. (C) Schematic picture showing the dissection plane in anteriorly located T3 rectal cancer only at the level of seminal vesicle. White arrows: DVF.