Transanal Total Mesorectal Excision: Description of the Technique

Abstract

Surgery remains the gold standard for the treatment of locally advanced rectal cancer. The most effective approach to reduce locoregional recurrence is total mesorectal excision (TME). However, obtaining an optimal TME is demanding, especially in low rectal tumors and anatomically unfavorable pelvis. Transanal TME (taTME) was developed to facilitate low pelvis dissection and potentially provide optimal outcomes for oncologic resection.

Current studies have reported satisfactory short-term outcomes. However, taTME is a technically challenging procedure and must be learned in an appropriate training process to allow for a safe implementation. Previous experience in laparoscopic and transanal surgery is strongly recommended. In this work, we provide a detailed discussion of the technique, based on the realization of more than 400 taTME interventions.

Spectacular transformations in rectal cancer surgery approaches have appeared in the last decades. While obtaining a total mesorectal excision (TME) has remained the main surgical objective to reduce locoregional recurrence since its description by Professor Bill Heald, ¹ different approaches have been developed to overcome inherent difficulties associated with pelvic surgery. In a search for less traumatic interventions, the laparoscopic approach to rectal surgery was shown to be safe and feasible in various studies published in the early 21st century. ^{2 3 4 5} However, the advanced laparoscopic skills required to achieve a complete TME have limited its adoption, and some studies have questioned the oncologic equivalence of laparoscopy and open surgery for rectal cancer. ^{6 7}

Working in the low pelvis with straight and rigid laparoscopic instruments is challenging and requires complex maneuvers. Moreover, the reduced visualization decreases the control of the distal transection of the rectum. Recently, a combined transabdominal-transanal approach was developed to overcome these obstacles: the transanal TME (taTME). ⁸ Several studies have been published in the literature describing the critical steps of a taTME. ^{9 10 11} Also, several groups have developed hands-on courses, international consensus conferences, and educational platforms to help in the safe implementation of this novel procedure. ^{12 13} The objective of this article is to give a detailed description of the taTME technique based on the experience acquired at the Hospital Clinic of Barcelona and accessible on the surgical education Web site: www.aischannel.com .

Patient Preparation

All patients with a diagnosis of rectal cancer undergo a thorough preoperative staging following accepted guidelines: a complete blood count and chemistry, a physical exam including a digital rectal examination, a complete colonoscopy, a computed tomography of the chest, abdomen, and pelvis, a pelvic magnetic resonance imaging, a rigid rectoscopy, and dosage of the carcinoembryonic antigen. Management of all cases is discussed in a multidisciplinary conference with medical oncologists, radiation oncologists, radiologists, and colorectal surgeons.

To follow an Enhanced Recovery after Surgery (ERAS) program, ¹⁴ patients should receive preoperative teaching for adequate physical and mental preparation. Patients should also meet an enterostomal therapy nurse before surgery for stoma site marking and education. Oral antibiotics and a mechanical cathartic bowel preparation are administered on the day before surgery.

In the operative room, the patient is placed on a bean bag in a lithotomy position after induction of general anesthesia. Legs are secured in adjustable stirrups, arms are tucked on both sides, and all pressure points are padded. A urinary catheter is inserted and a rectal enema is performed. A preoperative intravenous antibiotic prophylaxis is given prior to incision: cefazolin and metronidazole (ciprofloxacin and metronidazole in case of penicillin allergy). A thromboprophylaxis with subcutaneous unfractionated heparin is injected and intermittent pneumatic compression devices are placed on the lower legs.

Operative Room Preparation

A comprehensive list of the equipment needed is listed in Table 1 . TaTME can be performed with one or two surgical teams working simultaneously. Surgery at the Hospital Clinic of Barcelona favors a two-team approach for a safer and faster procedure. Although preferable, it requires the availability of two surgical teams (surgeon, assistant, scrub nurse). When a one-team approach is chosen, a sequential transabdominal-transanal dissection will be used. We suggest starting with the abdominal phase to obtain a left colon mobilization and occlusion of the distal colon during the subsequent purse-string creation in the rectal lumen. Otherwise, a pneumoretroperitoneum and proximal colon hyperinflation may occur.

Table 1. Material required for a taTME.

Devices required Two CO 2 insufflation system (standard and continuously insufflation systems) Two laparoscopy system Two electric scalpel (electrocautery) Two aspirators Two boxes of the basic instruments required for placement of trocars, removal of the specimen, and anastomosis Two optical devices (10 mm or 5 mm, 30° or 0°, and 3D) Two tables for laparoscopic instruments Two Mayo tables for basic instruments Two Allen hydraulic stirrups One special self-designed table for the transanal stage One special trocar (continuous insufflation system) that adapts to the CO 2 tube of the same brand One transanal platform (with removable cap) One 5 mm energy sealing device One EEA 29, 31, or 33 mm circular endostapler: standard or hemorrhoidal stapler (if a mechanical anastomosis is performed) One short linear endostapler (not always) with different sizes of cartridges depending on the type of anastomosis (end-to-side, colonic J pouch)

Transabdominal field • One optical device 10 mm. 30° or 0° • One CO 2 tube • One thermos to heat the optical device with 70°C distilled water • One kidney dish with physiological serum and povidone in 1% concentration • Ten large gauzes • Ten small gauzes (gauzes are counted) • One aspiration tube with a Yankauer aspiration tip One electric scalpel Sutures: • One 2–0 nonabsorbable polyfilament suture to fix the drain • One 0 polyfilament absorbable suture to close the fascia of the 12-mm trocar site • Four 3–0 polyfilament absorbable sutures for the ileostomy

Transanal field One camera system (3D or 30° 10-mm) • One CO 2 tube (continuous insufflation system) • One thermos to heat the optical device with 70°C distilled water • One kidney dish with physiological serum and povidone in 1% concentration • One small kidney dish with a diluted solution of 100 mL physiological serum and 1 mg adrenalin • One small kidney dish with lubricating gel • Ten large gauzes • Twenty small gauzes (gauzes are counted) • Two large surgical patties • One aspiration tube with a Yankauer suction tip • One electric scalpel • One Lone Star retractor • One set of EEA 25–31 mm calibrators • Two mini Deaver retractors Sutures: • One 0 nonabsorbable polyfilament to fix the transanal platform • One 0 nonabsorbable monofilament suture for the purse-string suture to close the rectal lumen • One 0 nonabsorbable monofilament suture tapercut needle for purse-string suture in the distal rectal cuff • One 3–0 absorbable polyfilament if a hemostasis stitch is required at the anastomosis • One 2–0 nonabsorbable polyfilament to fix the drain

Abbreviations: 3D, three-dimensional; taTME, transanal total mesorectal excision.

Note: Courtesy of AIS Channel.

Abdominal Phase of a TaTME

The main steps of the abdominal phase are listed in Table 2 . In this article, we describe a laparoscopic approach for this phase but parts or its entirety could be performed with a laparotomy or a robotic system, depending on the surgeon's experience and the patient's surgical history. First step is to obtain a pneumoperitoneum either with an open Hasson technique or with a Veress needle. In a two-team approach, the pneumoperitoneum pressure should be kept lower than the pneumorectum pressure to insure a good pelvic distension. It is usually set at 12 mm Hg in the abdomen and at 15 mm Hg in the rectum. Pressures can be equalized once abdominal and transanal dissection planes have connected (“rendez-vous”). A 10-mm trocar is inserted for the camera at the umbilicus. A thorough evaluation of the abdominal cavity (peritoneal and liver surfaces) is performed looking for metastatic disease missed on imaging. Then, trocars are inserted under direct vision as for a laparoscopic low anterior resection: two 5-mm trocars on the right side (lower quadrant and right flank) and a 5-mm one is inserted in the left lower quadrant for further retraction. Additional trocars can be inserted for further retraction depending on the patient's anatomy and surgeon's preferences. The operative table is tilted in Trendelenburg position with the right side down.

Table 2. Steps of the abdominal phase.

1. Insufflation of the pneumoperitoneum and abdominal inspection 2. Division of the inferior mesenteric vessels 3. Left colon mobilization and splenic flexure takedown 4. Colon clamping during transanal rectal purse-string 5. Upper rectum dissection 6. Specimen extraction: transabdominally or transanally 7. Colorectal anastomosis 8. Diverting loop ileostomy when needed

As for most low anterior resections, splenic flexure mobilization is usually necessary. In the authors' hospitals, a medial-to-lateral approach is favored. The inferior mesenteric vein (IMV) is identified near the inferior border of the pancreas. The peritoneum is opened medially and the vein is lifted with an atraumatic grasper. Next, a blunt dissection is performed toward the splenic flexure and the left colon lateral attachments, separating the left mesocolon from the retroperitoneum. The peritoneum is opened caudally and parallel to the IMV in direction of the inferior mesenteric artery (IMA). The peritoneal opening is continued under the superior rectal artery (SRA). A medial-to-lateral dissection is performed under the SRA. The IMA is lifted from the retroperitoneum by blunt dissection and the left ureter is identified after which the IMA is transected with a bipolar energy device or an endoscopic vascular stapler. The left colon and sigmoid colon lateral peritoneal attachments are divided. The lesser sac is entered at the junction of the transverse colon and the omentum, and the dissection is carried on toward the splenic flexure to meet with the medial and lateral dissections. At that stage, the colon mobilization should allow for a tension-free anastomosis. For further length, the IMV can also be divided at the inferior edge of the pancreas.

When the transanal team is ready to place the purse-string suture in the rectal lumen, the sigmoid colon is clamped with an atraumatic intestinal grasper. While the transanal phase progresses, the upper rectum dissection is started by opening the peritoneal reflection. Then, a TME plane is followed carefully. From the abdominal side, traction and countertraction on the rectum and surrounding structures help the transanal team in its dissection. Once the abdominal and transanal team have connected their planes of dissection, we proceed with the extraction of the specimen transanally or through a Pfannenstiel incision. We have recently incorporated indocyanine green fluorescence angiography for real-time intraoperative evaluation of bowel perfusion before proximal colonic transection and after anastomosis performance. A diverting loop ileostomy is created for low rectal anastomoses or following neoadjuvant therapy. A closed-suction drain is left in the pelvis if deemed necessary by the surgeon.

Transanal Phase of a TaTME

The transanal steps are listed in Table 3 . First, a digital rectal examination should be repeated to evaluate the distance between the tumor and the anal canal. A Lone Star retractor (Cooper Surgical, Trumbull, CT) is positioned around the anal margin to visualize the anal canal; it is especially useful in the case a hand-sewn coloanal anastomosis is planned or if an intersphincteric dissection is needed. Next, a transanal platform is inserted in the anal canal. At that stage, the patient should be under deep anesthesia with a complete muscle relaxation. Depending on the surgeon's experience, either a disposable flexible single-port device or a rigid platform can be chosen. We favor a flexible device (Gelpoint Path Transanal Access, Applied Medical Inc., Rancho Santa Margarita, CA). We believe it requires a shorter learning curve and provides more maneuverability. The downside is the need for an assistant to hold the camera. The device is secured to buttocks with 0 silk sutures. Three trocars are inserted in the platform cap in an inverted triangle position. The pneumorectum can be achieved with a standard intermittent flow insufflator or a continuous flow system (Airseal, Surgiquest Inc., Milford, CT). The latter provides a steadier pneumorectum pressure and evacuates smoke and humidity. A 30-degree 10-mm laparoscopic camera or a three-dimensional (3D) 10-mm laparoscopic camera is generally used. The 3D camera has a flexible tip that provides a greater angulation and limits the contact between the instruments.

Table 3. Steps of the transanal phase.

1. Transanal platform insertion and pneumorectum to 12–15 mm Hg 2. Purse-string distal to the rectal tumor 3. Rectotomy (perpendicular rectal wall transection) 4. Cephalad TME dissection 5. (Specimen extraction) 6. Anastomosis (either stapled or hand-sewn)

Abbreviation: TME, total mesorectal excision.

Once the pneumorectum is obtained, a visual inspection is performed and a tumor-free distal margin is chosen. The rectal lumen is closed with a purse-string suture, precisely 1 cm distal to the inferior edge of the tumor, assuring adequate distal resection margins. A size 0 polypropylene or polydioxanone sutures are generally used. The purse-string should be performed with small equal bites at the same rectal level to offer an airtight closure. This will avoid spillage of tumor cells or stools during the procedure or extreme inflation of the proximal colon. A rectal irrigation with a diluted iodine solution is repeated to remove any debris or floating tumor cells. The distal rectal mucosa is circumferentially scored with the electrocautery at the planned rectotomy site, thus creating a rectal “tattoo.” It should be placed outside the mucosal folds created by the lumen closure to avoid cutting the purse-string suture ( Fig. 1 ). Then, we proceed with a rectal wall transection (or rectotomy) cautiously, layer by layer with the electrocautery hook tip. Care should be taken to remain perpendicular during that transection to avoid a coning in the proximal mesorectum. The rectotomy is usually started on the posterior aspect of the rectum. A fibrous raphe is usually found in the posterior midline. The avascular TME space is reached after cutting through the muscle layers and the mesorectum fat. Its boundaries are the endopelvic fascia laterally, the presacral fascia posteriorly and the Denonvilliers' fascia anteriorly. Also, it should be remembered that the mesorectum is thinner anteriorly and distally.

Fig. 1.

Mucosa scoring after rectal lumen purse-string suture placement.

Once the TME plane is reached, the dissection is carried on cephalad. One should avoid any breaches in the surrounding fascias laterally or in the mesorectal envelope medially. While progressing proximally, the sacrum angulation has to be respected on the posterior side to avoid entering the presacral space and risking significant bleeding. Anteriorly, care should also be taken to avoid cutting through the Denonvilliers' fascia to prevent iatrogenic trauma to the urethra, seminal vesicles, prostate, or vagina ( Fig. 2 ). En bloc excision of a part of the Denonvilliers' fascia may be necessary in particular cases to insure a negative radial margin. Furthermore, the dissection should be done circumferentially to avoid anatomy distortion. Most of the dissection can be completed with the electrocautery hook, but the use of a bipolar forceps may be helpful occasionally to complete the hemostasis.

Fig. 2.

Sagittal view of a transanal total mesorectal excision (taTME) dissection. The transanal platform is located in the anal canal. Anterior and posterior planes of dissection are illustrated with dotted lines.

Anterior and posterior planes are generally easier to identify. They should be recognized first and to help in delineating the lateral planes of dissection. Damages to the pelvic neurovascular bundles can occur if the dissection goes too laterally at the mid-distal rectum level.

The dissection continues cephalad until reaching the abdominal cavity. If a single stapled double-purse-string anastomosis is planned, a 0 polypropylene suture is placed on the open rectal stump in a purse-string fashion. The two strands are left hanging on the anal retractor or through the transanal platform. Later, the strands will be tied on the anvil, the circular stapler spike, or on a catheter, depending on the anastomosis height ( Fig. 3 ). This will be described further in the “anastomosis” section of this article.

Fig. 3.

Double purse-string single stapled anastomosis.

For low rectal cancers, an open intersphincteric dissection might be necessary before the insertion of the transanal platform and before the lumen occlusion with an airtight purse-string. We suggest the Rullier's algorithm for the management of these tumors ¹⁵ : a standard coloanal anastomosis is performed if more than 1 cm of margin is present between the tumor and the anorectal junction; a partial or total intersphincteric resection if less than 1 cm is present or if there is an internal sphincter invasion, respectively. The transanal platform can be inserted once the intersphincteric dissection has reached a supralevator level. After, a taTME can be started following the above-cited technique.

Specimen Extraction

The specimen extraction can occur through an abdominal incision, or transanally. The choice will depend on various factors: tumor size and height in the rectum, mesorectum and pelvis width, and extent of colonic mobilization. A good candidate would be a patient with a small distal tumor, a slim mesorectum, and a large pelvis. When the specimen is removed transanally and a single-stapled double-purse-string is planned, a purse-string suture should be place on the open distal rectal cuff before extraction. Otherwise the extraction might cause undue stretching on the cuff and render the purse-string placement more difficult to perform. Whichever extraction site is chosen, it is important to avoid damaging the mesorectum or causing breaches in the mesorectal fascia. In most cases, a Pfannenstiel incision is created. It is safe and can be tailored to the tumor size. Another option is to proceed with an extraction through the stoma site opening.

Anastomosis

Different options are available for the anastomosis. A comprehensive paper by Penna et al describes the possibilities. ¹⁶ For most of the cases, we will proceed with a single-stapled double-purse-string anastomosis ( Fig. 3 ). In that case, purse-string sutures are placed on the proximal colon and on the open distal rectal stump. An anvil from a circular stapler is inserted in the proximal colon and secured in place with the purse-string suture. New staplers have been developed specifically for the TaTME. They have a straight design, a longer spike, and the possibility of inverting the distal purse-stringe suture ( Fig. 4 ). The stapler and the anvil are connected and the stapler is fired. For an easier purse-string knot tying on the distal rectal cuff, a section of bladder catheter or a similar 10 Fr drain tube can be inserted on the anvil. Once the purse-string knot is tied on the catheter, it is pulled down to bring together the proximal colon and the rectal stump ( Fig. 4 ). Then, the stapler and the anvil are connected, and stapler is fired.

Fig. 4.

Purse-string knot tying on a catheter placed on the anvil rod (left).

For a coloanal anastomosis, the proximal colon is brought through the anal canal. The specimen is transected with a linear stapler (if not removed through an abdominal incision). An opening is made on the antimesenteric side for a side-to-end anastomosis or the distal staples are removed for an end-to-end anastomosis. The coloanal anastomosis is created with four interrupted 2–0 polyglactin stitches at 3, 6, 9, and 12 o'clock position. Each stitch should include a full-thickness bite of the colon and a portion of the internal sphincter. The anastomosis is completed with an additional 8 to 12 interrupted 3–0 polyglactin stitches placed circumferentially.

The anastomosis is inspected visually and an air leak test is performed to test its integrity (not for a coloanal anastomosis).

Postoperative Care

The postoperative care should follow the hospital ERAS protocol and should not differ from a standard low anterior resection patient. Early feeding and mobilization are strongly encouraged. The closed-suction abdominal drain is removed before the patient's discharge. The diverting stoma is closed at least 3 months after surgery or later if adjuvant chemotherapy is given. We suggest that all taTME cases should be included in a study or a registry to monitor outcomes. ¹⁷

Abbreviations

TME

Total Mesorectal Excision

TaTME

Transanal Total Mesorectal Excision

CEA

Carcinoembryonic Antigen

ERAS

Enhanced Recovery After Surgery

TAMIS

Transanal Minimally Invasive Surgery

TEM

Transanal Endoscopic Microsurgery

IMV

Inferior Mesenteric Vein

IMA

Inferior Mesenteric Artery

SRA

Superior Rectal Artery

Funding Statement

Funding No source of funding to disclose.