Intersphincteric Restorative Proctocolectomy for Malignant Disease

Ron G. Landmann

INTRODUCTION

While addressing the issue of rectal cancer treatment, four major objectives are uniformly pursued: (1) cure—including primary local resection with negative margins and subsequent prevention of locoregional (LR) and distant recurrence; (2) decreased morbidity and mortality; (3) preservation of sexual and urinary functions—as manifested by erectile dysfunction, retrograde ejaculation, vaginal dryness, dyspareunia, and difficulty voiding; and (4) maintenance of intestinal continuity/avoidance of a permanent stoma. Currently, despite the advances in chemotherapeutics, biologics, and radiation therapy, surgery is the primary modality to achieve these goals.

Most surgeons with experience in operating on the rectum have at some point dealt with the difficulties associated with a narrow pelvis and its confines and anatomic complexities and intricacies. During the times before modern anesthesia, when an even greater importance was placed on the furtiveness of surgical techniques, most surgeons avoided venturing into the deep and dark den of the rectum. The earliest experience with rectal surgery includes transanal resection of tumors. This approach caused minimal morbidity, but was plagued by a near universal incidence of tumor recurrence. The advent of potent, safe, and efficacious anesthetic techniques has allowed surgeons the opportunity to perform increasingly more complex and delicate rectal operations utilizing a combination of transanal, abdominal, and perineal approaches.

Ernest Miles first published his technique of an abdominoperineal resection (APR) for rectal tumors in 1908. This technique was gradually modified so that by 1924, reports demonstrated a significant and welcome decrease in local recurrence rates from nearly 100% to the range of 30%. Unfortunately, this procedure carried significant morbidity related to a poorly healing perineal wound, autonomic nerve damage resulting in impotence, and a permanent stoma reminding patients of their disease. Still, it became accepted as the standard of care because it provided the best chance of cure. To this day, surgical management of rectal cancer has focused on modifications of Miles’ technique in an effort to improve oncologic results and minimize the associated morbidities.

The APR was also being utilized for the management of perianal Crohn’s disease as well as ulcerative colitis and other septic complications. The healing of these perineal wounds was an even greater challenge than those created by surgery for malignancy. The perineal wounds in these patients were initially managed by loose approximation of the skin edges and sump drainage. In 1970, reports were published about successful outcomes after primary suture of the perineal wound with closed suction drainage. Oates described 41 of 53 patients with successful wound healing. A modification of the APR, intersphincteric proctectomy, was first described for benign diseases by Lyttle in 1977. The thought was that sparing the striated external sphincter and pelvic musculature would create a smaller dead space and provide another layer of strong and healthy tissue to aid in wound closure. This expectation was borne out in studies that demonstrated significant improvements in wound healing over the time period of 1 year. In fact, studies showed that when sepsis was initially controlled via drainage or diversion, 1 year after intersphincteric proctectomy, 100% of wounds in patients who did not receive preoperative steroids were observed to have healed.

In 1972, Lee and Dowling reported on a technique that they believed would decrease the morbidity associated with impotence after an APR and named it a Perimuscular Dissection of the Rectum. The
thought was that the lateral dissection into the pelvis and superiorly into the region of the prostate resulted in nerve damage that led to impotence. Avoidance of dissection in these areas would thus result in decreased morbidity. Subsequent studies evaluating this technique revealed a dramatic decrease in the incidence of postoperative impotence.

LR recurrence rates were still unacceptably high and it was not until 1979 when Heald advocated for a strict dissection technique that the LR recurrence rates started falling, precipitously. His technique was based on a progressive research providing a better understanding of the embryology of the rectum and perineum combined with the improved understanding of the anatomic pathways of the nerve fibers involved in erection and ejaculation. His technique was optimized to reduce the risk of damage to the cavernosal fibers anterior to the distal rectum along the periprostatic plexus anterior to Denonvilliers’ fascia, keep the dissection away from the pelvic side walls and the sympathetic fibers, and by incorporating the mesorectum and associated lymph nodes into the surgical pathology specimen. He named his technique the total mesorectal excision (TME) and subsequently published his findings in 1982. In that paper, he described the precise sharp dissection of the avascular plane between the presacral fascia and the fascia propria (“the holy plane”) to achieve a resection specimen with an “intact mesorectal envelope.” The goal of achieving a negative circumferential resection margin (CRM) and consequently reduced recurrence were thus first proposed.

The morbidity associated with a permanent stoma after rectal resection has decreased significantly mainly due to the decrease in the percentage of rectal resection requiring an APR. Aided by the advancement in the laparoscopic technique and the stapler technology, the APR has been replaced with restorative surgical procedures such as ultra-low anterior resection (uLAR) with various reconstructive modalities. Furthermore, advances in adjuvant and neoadjuvant therapies have allowed for oncologically acceptable results with sphincter sparing resection even in tumors that involve the internal sphincter.

The distal resection margin (DRM) has been a point of contention and debate among colon and rectal surgeons and surgical oncologists. Many began questioning the previous recommendations and guidelines requiring a 5 cm DRM. The National Surgical Breast and Bowel Project found no significant differences in survival or recurrence when comparing DRMs of less than 2 cm, 2-3 cm, and higher than 3 cm. Moore published a series from Memorial Sloan Kettering Cancer Center demonstrating that intramural tumor extension beyond the gross mucosal edge was uncommon and usually less than 1 cm after the preoperative combined-modality therapy. Later, the same group deemed that a 1 cm margin was acceptable in patients in whom sphincter preservation was required. However, the author still recommends obtaining a frozen section pathological review prior to proceeding with reconstruction. Newer arguments based on the Norwegian Colorectal Cancer Group have now recommended that even more important than a prognostic factor toward decreased LR recurrence, distant metastasis, and overall survival is a negative circumferential margin of greater than 2 mm. However, these data were more strongly prognostic in higher lesions >6 cm above the anal verge.

Current standard practice, based on preoperative staging, either with endorectal ultrasonography or magnetic resonance imaging (MRI), recommends low anterior resection (LAR) or APR for most advanced (i.e., T3 or N+) distal lesions, within 0-5 cm above the dentate line. All the advances in rectal surgery described have been integral to the advent of intersphincteric restorative proctocolectomy (IRP), while continuing to meet the above primary objectives. In this procedure, the internal anal sphincter—a continuation of the rectal wall—is completely or partially excised to obtain the necessary full-thickness DRM. Subsequent coloanal anastomosis to the remaining sphincter complex thereby restores intestinal continuity, with a goal of improved quality of life while preserving oncologic and functional outcomes. With these refinements and improvements in both neoadjuvant chemoradiation therapy and surgical techniques, patients now have another option available for sphincter preservation.

CONSIDERATIONS DURING INTERSPHINCTERIC PROCTECTOMY

INDICATIONS FOR INTERSPHINCTERIC RESECTION

Patient Selection and Preoperative Evaluation

Due to the inherent morbidity associated with a permanent stoma, a restorative proctocolectomy may be offered to all patients with tumors that are amenable to the procedure. Patients generally to be considered for intersphincteric resections (ISRs) are those patients with Stages I-III distal rectal tumors (pretreatment T1-T3, N0-1) within 4 cm of the anal verge that do not have evidence of external
sphincter involvement. The decision to perform a restorative procedure should be made in conjunction with the patient after discussing the likely postoperative oncologic and perhaps more importantly, functional outcomes. Whereas involvement of the internal sphincter by an invasive disease should not be viewed as a contraindication to ISR, invasion of the external sphincter or the musculature of the pelvic floor would make the disease incurable via IRP. For the latter, APR is required for appropriate oncological resection and outcomes. A digital rectal examination that shows fixation of the tumor should also be considered a contraindication because it likely means that the tumor has broken through the intersphincteric plane and has fixed the internal sphincter—an embryological derivative and continuation of the rectal wall—to the external sphincter or the pelvic floor musculature. Such a disease would be better managed via APR. A preoperative pelvic MRI or endoanal ultrasound is instrumental in assessing the extent of tumor spread. Indeed, any tumor that has sphincter involvement, prior to the use of neoadjuvant combined-modality therapy, should be excluded from an IRP and offered a standard APR, despite improvement after the therapy. Tumors that respond with downstaging and/or downsizing after neoadjuvant chemoradiation therapy generally make patient candidates for LAR/IRP. A chest X-ray and a CT scan of the abdomen and pelvis should be performed to rule out Stage IV metastatic disease. In the case of low rectal tumors, care should be taken to examine the groins for evidence of inguinal lymphadenopathy. The results of these preoperative evaluations, in conjunction with those following the neoadjuvant therapy, should be used to determine the distal margin of resection and potential for resection with maintenance of intestinal continuity/sphincter preservation.

Body habitus also plays a significant role in operative decision making. Ideally, the patient should not be obese (BMI < 30-32 kg/m²). Patients who are: male, have a narrow pelvis, or a long anal canal may also make it more difficult to perform an ideal, oncologic resection. Indeed, an IRP is more likely to be performed in patients who are male, have distal tumors, or increased BMI due to difficulty introducing stapling devices (for LAR).

It is also important to determine the patient’s preoperative continence. This assessment can be made via history, digital rectal examination, manometry, or a combination of these methods. In patients with good sphincter function on digital rectal examination but recent development of clinical incontinence, the dysfunction may be attributable to the neoplastic process, and it is reasonable to expect that they may benefit from an IRP. Other patients with preoperative incontinence may be better served with a permanent stoma. When possible, these patients may benefit from an intersphincteric non-restorative proctocolectomy due to its healing benefits over APR, especially after undergoing neoadjuvant chemoradiation therapy. Although age per se is not an exclusion criteria, generally older patients have decreased sphincter tone and also less physiological reserve of their remaining musculature after undergoing radiation therapy and internal sphincter resection. A preoperative evaluation with a wound care and ostomy nurse for stoma care teaching and stoma marking is pivotal in these patients and for long-term success of these patients.

CONTRAINDICATIONS TO INTERSPHINCTERIC RESECTION

There are certain exclusion criteria that are generally accepted when evaluating ideal candidates for IRP: pretreatment involvement of the external sphincter by tumor; inadequate distal margin (<1-2 cm); poor preoperative (or anticipated postoperative) sphincter function; patient preference; or an initial, pre-neoadjuvant uT3 lesion with an external sphincter complex involvement. When looking at a nationwide database, factors that were noted to be independent predictors of sphincter preservation included young age, proximal lesions, non-fixed lesions, and institution. Although not specifically addressed, individual training, technique, and outcomes are likely to be attributable to the success of an IRP. One cannot stress enough the importance, as with any procedure, of specialty training and experience mandatory for selecting and then completing these procedures. There is a high learning curve, particularly when approached laparoscopically. Furthermore, a multi- or interdisciplinary approach to evaluation and selection of these patients may help in the postoperative period.

SURGICAL ANATOMY AND CONSIDERATIONS

Autonomic Nerves in Rectal Dissection

During any operation for rectal disease, whether benign or malignant, the surgeon should be acutely aware of the innervations and distribution of the autonomic nerves and their relation to the target resection specimen. Trauma to the autonomic nerves may occur at several points. During high ligation
of the inferior mesenteric artery (IMA), close to the aorta, the sympathetic preaortic nerves may be injured. Division of both superior hypogastric plexus (SHP) and hypogastric nerves may also occur during dissection at the level of the sacral promontory or in the presacral space. In such circumstances, sympathetic denervation with intact nervi erigentes results in retrograde ejaculation and bladder dysfunction. The nervi erigentes are located in the posterolateral aspect of the pelvis, and at the point of fusion with the sympathetic nerves are closely related to the middle hemorrhoidal artery. Injury to these nerves completely abolish erectile function. The pelvic plexus may be damaged either by excessive traction on the rectum, particularly laterally, or during division of the lateral stalks when this is performed close to the lateral pelvic wall. Finally, dissection near the seminal vesicles and prostate may damage the periprostatic plexus, leading to a mixed parasympathetic and sympathetic injuries. This can result in erectile impotence as well as a flaccid, neurogenic bladder. Sexual complications after rectal surgery are readily evident in men, but are probably underdiagnosed in women.

Surgical Technique

Various descriptions of intersphincteric restorative proctectomy have been presented in the literature over the past 40 years. This extended resection for rectal malignancies is predicated on the knowledge that rectal tumor infiltration is initially limited by an embryonic plane between the visceral structures and the surrounding somatic skeletal muscles of the pelvic floor (Fig. 20-1). IRP attempts to rid the patient of the disease while the tumor is still confined to this envelop. Throughout the dissection, particular attention is paid to minimize damage to the sympathetic and parasympathetic fibers that are involved in bladder function and sexual potency. Whereas damage to the sympathetic fibers alone leads to a decreased ability to attain orgasm, parasympathetic or combined damage results in impotence in men and vaginal dryness in women, manifesting as dyspareunia.

Fecal Diversion

The author’s and editors’ preference is for fecal diversion of all patients that undergo IRP. There remains some controversy about the role of diversion in rectal surgery due to the morbidity associated with a stoma as well as a second surgery to reverse it. However, we feel that, the increased salvage rate, decreased rate of reoperation, and decreased clinical significance of anastomotic failures in patients with diverted stomas makes the diverting procedure justifiable.

Although there is one randomized prospective trial that shows decreased morbidity in terms of postoperative ileus and small bowel obstructions with a diverting transverse loop colostomy, our preference is to utilize a diverting loop ileostomy. As the splenic flexure is often mobilized to provide adequate length for a coloanal anastomosis during an IRP, maturing a transverse loop colostomy
becomes significantly more difficult than a diverting loop ileostomy. The operation to reverse a loop ileostomy is also much easier with decreased postoperative morbidity in terms of wound infection and abdominal wall hernia formation.

FIGURE 20-1 Schematic representation of the distal anorectal canal. The mesorectum narrows and is completely terminated at the point of meeting the puborectalis muscles and the levator plate. This then proceeds circumferentially in a caudad fashion as the external sphincter muscle, a somatic muscle along the anal canal. Medially, the internal sphincter muscle, a visceral smooth muscle, is observed as a continuation and in apposition to the rectal wall, and is separated by the intersphincteric plane or space from the external sphincter muscle in the embryonic plane by a glistening white peritoneal reflection.

The anastomosis is studied 6 weeks later and if the results are satisfactory, the diversion is reversed.

Total Mesorectal Excision

The abdominal phase of the dissection has been described via laparotomy, laparoscopy, and now robotics. It is broadly accepted that the approach to cancers of the rectum should include sharp TME. Others have advocated that tumors, particularly those in the upper part of the rectum, may be resected if adequate margins can be achieved—particularly at least 5 cm of mesorectum distal to and proximal from the rectal tumor. If these mesorectal margins cannot be attained, then complete TME is advocated. Generally, an LAR with a stapled anastomosis can be performed if sufficient distal margins are achieved and a stapler is able to be introduced at or above the level of the levator plate. In the setting of more distal tumors requiring intersphincteric restorative proctectomy, our preference is to perform a complete laparoscopic TME. Based on numerous trials, and also summarized by position statements from the American Society of Colon & Rectal Surgeons and the Society of American Gastrointestinal and Endoscopic Surgeons, laparoscopic techniques for curable colon and rectal cancer have been deemed to be a safe alternative when correct oncological techniques are followed. However, it is critically important to emphasize that a laparoscopic approach is not a simple procedure, and that it requires proper training and experience in advanced minimally invasive surgery. Most of the data presented are based on national data evaluating laparoscopic colon and rectal surgery and extrapolated based on multicenter experience with laparoscopic rectal cancer surgery. Recently, two Western randomized multicentered trials have completed investigating the use of the laparoscopic (and in some cases, robotic) technique for rectal cancer TME. For these trials, the American College of Surgeons Oncology Group Z6051 and the Australasian Laparoscopic Cancer of the Rectum Trial (ALaCaRT) used a surrogate pathological metric to evaluate appropriate surgical resection and attempted to use this composite index as an oncological marker for appropriateness of resection. This surrogate was a summation of completeness of the TME, negative circumferential margin, and negative distal margin. Although there were no differences between the open and laparoscopic approaches in these individual outcomes, the composite index unfortunately did not meet the non-inferiority benchmark criteria, and caution was advised when recommending or performing rectal cancer operations using the minimally invasive laparoscopic approach. There have been numerous editorial reviews and commentary in societies on the outcomes of these trials and currently, in the United States, centers continue to proceed with minimally invasive, and in particular, robotic dissections for rectal cancer. Long-term oncological outcomes from the above trials are still pending.

PREOPERATIVE PLANNING

As with all operations for rectal adenocarcinomas, patients should be appropriately and thoroughly evaluated. A complete and full colonoscopy should be performed and documented to exclude any other synchronous lesions. Flexible sigmoidoscopy after neoadjuvant chemoradiation therapy may be utilized to assess clinical response. Preoperative imaging with computed tomography of the chest, abdomen, and pelvis should be performed to exclude metastatic disease and/or progression during chemoradiation therapy. Dedicated MRI with rectal cancer protocols (with or without endorectal coil or endoluminal gel) should be performed to document local staging, and in particular, assess closeness of the circumferential and distal tumor extent. These latter features may affect the extent of operation performed. A carcinomembryonic antigen level should be drawn preoperatively as a baseline. Baseline assessment of sphincter tone should be performed prior to the operation to assure appropriate resting and squeeze tone. Absent or diminished tone is a contraindication to ISR. Finally, documentation of a multidisciplinary tumor board review of the patient and their disease and subsequent plan is highly suggested.

Preoperatively, all patients are placed on an enhanced recovery protocol. It is the surgeon’s preference to have patients complete a complete oral antibiotic and mechanical bowel prep the day prior to the operation. In addition, all patients receive intravenous parenteral prophylactic antibiotics according to Joint Commission Surgical Care Improvement Project guidelines. Patients also receive preoperative oral acetaminophen, celexocib, and gabapentin in the holding area as part of the enhanced recovery protocol.

SURGERY/DESCRIPTION OF TECHNIQUE

The procedure may be broken down conveniently into seven distinct steps: (1) medial-to-lateral mobilization and high intracorporeal vascular division of the IMA and vein; (2) mobilization of the sigmoid colon and left colon; (3) splenic flexure mobilization and inferior mesenteric vein transection; (4) sharp TME with en bloc lymphadenectomy; (5) intersphincteric distal dissection via abdominal approach (and double-stapled anastomosis if possible) or via transperineal transection/intrasphincteric dissection; (6) extracorporeal transperineal creation and anastomosis of a reservoir; and (7) temporary diversion. Following is described the laparoscopic and robotic techniques for an IRP.

Intraoperative Preparation and Positioning

The patient is placed in a modified lithotomy position and both legs are secured in Allen stirrups. Intraoperative evaluation of the rectal tumor is performed via digital rectal examination and rigid proctosigmoidoscopy to determine resectability and the site of the distal resection. The rectum is then irrigated with a cytocidal solution of diluted Betadine. Both the abdomen and the perineum are prepped and draped in a sterile manner. In females, the vagina is also sterilely prepped. Cystoscopy and bilateral ureteral catheter placement may be helpful in the setting of an irradiated pelvis to help visualize the ureters during dissection.

Laparoscopic Port Placement

Peritoneal access is obtained utilizing the open Hasson technique via a 1 cm supraumbilical incision. On obtaining pneumoperitoneum, a 10 mm 30-degree scope is utilized to perform a diagnostic laparoscopy. Particular attention is paid to the liver surface as well as the surface of the peritoneum to evaluate for metastatic disease. A 10-12 mm is placed in the right lower quadrant about 2 cm medial and 2 cm cephalad from the anterior superior iliac spine. An additional 5 mm port is placed in the right upper quadrant about 8 cm cephalad from the previous right lower quadrant port. A final 5 mm port may be placed in the left lower quadrant if needed for later use. This port can help with retraction of the rectum out of the pelvis, defining the anterior dissection plane, and in mobilization of the splenic flexure.

Robotic Port Placement

Currently, the author prefers performing most of the distal rectal dissections with the aide of the robot. The only robots currently on the market are the Intuitive da Vinci Si and Xi platforms (Intuitive Surgical, Inc., Sunnyvale, CA). The robotic system allows for enhanced visualization due to the 3D stereoscopic view and enhanced distal articulation and dissection due to the wristed instrumentation. In addition, in these complex cases, surgeon ergonomics are improved over laparoscopy and certainly more so over conventional open abdominal approaches.

Port placement for both Si and Xi platforms is generally similar. Advantages of the Xi platform include smaller ports, a levitating/articulating boom/arm positioning system, and also port-hopping that allows for the transfer of the camera to various ports, enabling full mobilization of the splenic flexure and also the rectum with single docking. Using the Xi system, a supraumbilical 8-mm camera port is placed about 15 cm cephalad to the pubis. This is performed using an optiview technique. Pneumoperitoneum is attained and similar to conventional open and laparoscopic approaches, diagnostic evaluation to exclude peritoneal or hepatic metastatic disease is performed. When local, non-metastatic disease is confirmed, a stapling port is placed in the right lower quadrant approximately 3 cm medial and superior to the anterior superior iliac spine, and then three additional 8-mm ports are placed as follows: right upper quadrant parallel to the RLQ port; left mid-abdominal port approximately 2-3 cm cephalad to the umbilical port and along the mid-clavicular line; and left lateral port parallel to the umbilicus along the anterior axillary line (Fig. 20-2). With this port placement, single-docking feasible to mobilize the colon from the mid-transverse colon distally to and through the intersphincteric plane around the anorectal canal. The addition of Table Motion software with the Trumpf Medical TruSystem 7,000 surgical bed (both, Trumpf Medizin Systeme GmbH, Saalfeld, Germany), allows for repositioning of the patients while the robotic (Xi) system is docked, enabling splenic flexure mobilization and single docking.

FIGURE 20-2 Robotic low anterior and intersphincteric port placement using the Intuitive daVinci Xi platform. With this setup, the patient bed is initially positioned in 20 degrees Trendelenburg and 10 degrees right inclination for the total mesorectal excision portion of the operation. The robot is docked perpendicularly from the patient’s left side. Instrumentation is as follows: 1—bipolar fenestrated grasper for static retraction of the distal sigmoid and anterior retraction of the vagina or prostatic structures; 2—Cadiere grasper for dynamic grasping and manipulation; 3—0 degree 8 mm robotic camera; and 4—monopolar scissors, bipolar vessel sealer, and 45 mm endostapler. When port-hopping for splenic flexure mobilization, the bed is repositioned into reverse Trendelenburg position and the Cadiere grasper moved to the assistant port and monopolar scissors to port 2.

Step 1: Medial-to-Lateral Mobilization and High Ligation of Inferior Mesenteric Artery

With the patient in slight Trendelenburg position and airplaned to the right, the medial-to-lateral mobilization is initiated. Although some have used energized shears/electrocautery devices, the author contends that an ultrasonic dissector or bipolar vessel sealer may subsequently have a role in later portions of the case for IMA transection and maintenance of hemostasis. The mesentery of the rectosigmoid is tented anteriorly directly overlying the sacral promontory, just to the left of the right common iliac artery. With a gentle application of coagulation current electrocautery in this area, the retroperitoneal presacral space begins to billow as carbon dioxide enters this plane and diffuses and expands the alveolar tissue. Then, dissection of the mesocolon of the rectosigmoid with the IMA is proceeded in the space between the mesentery and the autonomic nerves overlying the aorta. Care is taken to identify the left ureter and to preserve its posterolateral position (Fig. 20-3). Once these vital structures are identified, combinations of medial-to-lateral and lateral-to-medial are continued cephalad to identify the IMA and its origin at the aorta.

FIGURE 20-3 During medial-to-lateral mobilization, the mesentery of the rectosigmoid is tented anteriorly overlying the aorta and autonomic nerves with visualization of the retroperitoneal structure. The appropriate plane is identified with a positive observation of the retroperitoneal reflection line, the ureter and the left external iliac artery. Prior to this point, during dissection, care should be taken not to disrupt the autonomic nerves overlying the aorta.

FIGURE 20-4 High ligation of the inferior mesenteric artery (IMA). Note the ureter and pelvic sidewall structures on the left clearly identified and preserved out of harm’s way. The takeoff of the IMA off the aorta is seen with high ligation and transection (leaving a 1-cm stump) with the robotic vessel sealer.

A high ligation of the IMA is performed. The relative anatomy of the sympathetic nerves in this region should be kept in mind while performing this segment of the dissection. The SHP and the origin of the hypogastric nerves overlie the aorta, and the sacrum need to be visualized and preserved. They lie behind the IMA as it travels toward the rectum. These sympathetic fibers can sometimes be incorporated in the IMA pedicle if ligation of the IMA is performed too close to its origin from the aorta. Injury to these structures may result in retrograde ejaculation or vaginal dryness.

With the sigmoid colon on stretch and the patient airplaned to the right, mesenteric dissection is continued proximally until the vascular pedicle containing the IMA is identified. A window is created around the IMA. High ligation of the IMA is then performed just distal to its takeoff from the aorta. The author prefers to utilize an energy device (robotic bipolar vessel sealer or laparoscopic advanced energy ultrasonic dissector) for this ligation (Fig. 20-4). Alternatives include a mechanical endostapler of the appropriate staple height.

Step 2: Left Colon Mobilization

Just proximal to this IMA transection and ligation, the mesocolon is then divided in a perpendicular fashion to the level of the descending-sigmoid colon junction. Prior to transection of the colon and subsequent anastomosis, the colon proximal to the mesocolic division is evaluated for appropriate vascularity. This is currently performed using an intravenous injection of 4 ml of indocynanine green and endoscopic fluorescence imaging (Novadaq Systems, Ontario, Canada). Continued proximal dissection of the descending colon mesentery from the retroperitoneal structures is performed and facilitated by downward dissection of the white retroperitoneal reflection line. This dissection is continued proximally till above the upper pole of the kidney. In some cases, this mobilization can be continued and the wrong plane entered by dissected inferior/posterior to the pancreas. If this happens, the appropriate plane should be reentered separating the transverse mesocolon and pancreas keeping these structures separate anteriorly and posteriorly, respectively. The inferior mesenteric vein is also then dissected free and divided using another firing of the vascular stapler or ultrasonic dissector or bipolar vessel sealer. These maneuvers allow enough proximal colon length to perform reconstruction with a tension-free anastomosis.

Step 3: Splenic Flexure Mobilization and Inferior Mesenteric Vein Division

The descending colon is mobilized by freeing its remaining lateral abdominal wall attachments along the line of Toldt. These are all that will be left after previous cephalad medial-to-lateral mobilization of the mesentery from the retroperitoneum. This dissection is carried out proximally to the splenic flexure. The patient is then placed in slight reverse Trendelenburg position and starting approximately halfway between the hepatic flexure and the falciform ligament, the gastrocolic omentum
and its attachments to the transverse colon are divided. Dissection is carried out distally toward the previous dissection plane. The splenic flexure is thus completely and fully mobilized. Care should be taken to preserve the middle colic artery and vein. The inferior mesenteric vein should be divided at this point if not otherwise done. This should be done in a high fashion immediately caudad to the pancreas. This allows for appropriate tension-free length for the descending colon to reach the anus. The mesenteric dissection may proceed proximally to the level of the ligament of Treitz. In certain cases, with challenging splenic flexures, it may be easiest to enter into the lesser sac by opening up the relatively loose alveolar space immediately superior to the ligament of Treitz within the transverse colon mesentery. Dissection can then proceed anterograde along the distal transverse colon and distally to mobilize the splenic flexure until the prior transection is met from below.

Step 4: Sharp TME with En Bloc Lymphadenectomy

Attention is then turned to the sacral promontory and a sharp TME is performed in the bloodless plane. Laparoscopically, the plane is maximally visualized via lateral manipulation performed with the aid of the left lower quadrant abdominal port site and cephalad-anterior retraction of the rectum performed via the right upper quadrant port site. Robotically, the lateral-most port functions as a static grasper retractor for cephald-anterior retraction of the rectosigmoid and the more medial left-abdominal port functions as the dynamic retractor. Both hypogastric nerves overlying the sacral promontory and proceeding distally along the pelvic sidewalls are identified and preserved (Fig. 20-5). Dissection is carried out initially posteriorly, followed by laterally, and finally anteriorly. Care should be taken to find the correct plane of dissection, described by Heald as the “holy plane of rectal surgery,” just outside the fascia propria as the hypogastric nerves pass tangentially to it and medial to the ureter. This is most easily appreciated as a white, loose, alveolar plane. Dissection distally along this plane is easily performed sharply with electrocautery or energy devices.

The inferior hemorrhoidal plexus (IHP) sends delicate branches to the rectum that travel in the lateral ligaments. The routine use of large clamps to ligate the lateral ligaments in an attempt to avoid hemorrhage from the middle rectal artery is unnecessary because this vessel is found in only 20% of the patients. Utilization of these large clamps may increase the risk of damaging the IHP. We do not routinely include the entirety of Denonvilliers’ fascia (believed to be the conglomerate of two layers of the most distal pelvic peritoneum after the space within the layers is obliterated during embryogenesis) in our surgical specimen, unless there is a reason to believe that it would be required to obtain an R0 resection—that is, an anterior lesion.

Care should be taken not to damage the delicate cavernosal fibers while performing the anterolateral separation of the distal rectum from the prostate and the seminal vesicles during both the abdominal and perineal portions of this dissection (Fig. 20-6). The fibers are easy to damage as evidenced by
case reports of patients suffering from neurogenic impotence after the injection of sclerosant in too deep of a plane as an attempted therapy for anteriorly located hemorrhoids. These fibers cannot be visualized, making knowledge of their location and pathway particularly crucial. After exiting from their sacral roots, they pass from the pelvis anterolateral to the rectum on their way to pierce the urogenital diaphragm before entering the corpora. Damage can be avoided by performing delicate and avoiding overaggressive rectal dissection at the 2 and 10 o’clock positions, as this is where the cavernosal fibers are at greatest risk. Minimally invasive techniques and laparorobotic visualization aids in this dissection by affording a high-definition and magnified view of the dissection planes with minimal traction artifact. This dissection is carried down to and past the levator plate and into the intersphincteric space. At the completion of the TME, the specimen, with its intact fascia propria encompassing the mesorectum and lymph nodes, has been described as a glistening baby’s bottom posteriorly with two lobes.

FIGURE 20-5 Initiation of the sharp total mesorectal excision with monopolar scissors. The left and right superior hypogastric nerves are visualized (labeled laterally) immediately adjacent and outside the fascia propria in the presacral space. This plane is maintained and the white loose alveolar tissue is sharply dissected posteriorly and then laterally and finally anteriorly to the level of the levator plate.

FIGURE 20-6 Left anterolateral distal pelvic dissection. The seminal vesicles and Denonvilliers’ fascia overlying the anterior rectum (anterior based tumor) are seen and the levator plate and puborectalis musculature is evident at the interface of the rectum/mesorectum and pelvic floor.

Step 5: Intersphincteric Dissection

ROBOTIC INTERSPHINCTERIC DISSECTION (STEP 5A). At this point, if the anastomosis is distal enough that the dissection has proceeded within the intersphincteric plane and distal to the tumor with sufficient margin, two options exist. Traditionally, perineal dissection from below was performed to complete the dissection (see the following).

A second technique, facilitated by robotic systems, allows for avoidance of intersphincteric dissection and handsewn anastomosis from below. With the aid of the robotic system, dissection from the abdominal phase has improved to the point that perineal dissection is significantly less commonly done. When performing the TME dissection from above, the levator plates are encountered. With improved 3D visualization and wristed instrumentation, the surgeon is then able to identify the curvature of the puborectalis circumferentially as it encircles and wraps around the distal anorectal canal. This plane can be visualized with its peritoneal reflection line (a thin white filmy layer). This is appreciated as the embryonic plane between the visceral structures of the internal sphincter musculature and the surrounding somatic skeletal muscles of the pelvic floor and external sphincters. With care, the dissection can proceed distally in this intersphincteric plane circumferentially. Once an appropriate distal margin has been achieved, as verified digitally or endoscopically, the anorectal canal can be divided. The robotic platform for stapling across the distal rectal/anal canal is afforded due to improved articulation and instrumentation. This leaves a very distal/short Hartmann’s type anal bud or stump, typically at or just above (and if desired, below), the dentate line (Fig. 20-7). The dentate line may be observed in the proximal colorectal specimen.

At this point, a stapled anastomosis can then be created—with accordant avoidance and dependence/utilization of a handsewn anastomosis. To proceed at this point, if no perineal portion is required, the site of planned ileostomy is opened up and a wound protector is inserted through the abdominal
wall. The stapled end of the distal anorectum and proximal rectum is then extracorporealized. The colon is divided between clamps at the previous mesenteric transection line and where appropriate, proximal vascular supply has been assured. Frozen section pathological review should ascertain and confirm appropriate distal margins. If the margin is inadequate, then the surgeon should proceed with a perineal dissection (Step 5b, below) or convert it to an APR.

FIGURE 20-7 The bare anorectal canal has been transected with the robotic stapler. The anal transection line and distal anal stump is evident after an anterior-posterior division. The puborectalis and levator plate are seen and then more medially there is a change in orientation of the muscle fibers. The circular muscle fibers of the external anal sphincter muscles are evident encircling the anal stump. The observer will note that the transection is distal/caudad to the mid and upper external sphincter muscle fibers.

An appropriate colonic conduit is then created (see Step 6 in the following). The notable difference is that the anvil of the end-to-end anastomotic (EEA) stapling device is inserted within the lumen of the proximal colon and brought out on the antimesenteric surface at the proposed site of anastomosis to the anal stump. The colotomy at the prior transection is closed using an endomechanical stapling device. The colonic conduit is placed back within the peritoneal cavity. Under direct visualization, the EEA stapler is carefully and slowly inserted to abut the anal staple line. With anterior retraction of the vagina or prostate, the spike is then slowly advanced through the wall of the anal canal posterior or immediately lateral to the distal transection staple line. The anvil is then mated to the spike and while assuring that there is no twisting or kinking of the colon or its mesentery, and similarly that there is no tension on the proximal colon conduit, the stapler is then closed and fired. In some cases, careful pathological review may yield observation of the dentate line in the distal anastomotic ring after a double-stapled intersphincteric coloanal anastomosis (Fig. 20-8).

Laparoscopic evaluation and testing of the anastomosis while submerged under sterile saline irrigation and proximal occlusion with flexible endoscopy helps define viability, patency, hemostasis, and absence of an air leak at the anastomosis as well as viability of the proximal colon and anus. Once confirmed, the surgeon may proceed to creation of a diverting loop ileostomy (Step 7).

Only gold members can continue reading. Log In or Register to continue