Transanal Endoscopic Microsurgery

Fig. 22.1

Treatment algorithm

1.

Medically compromised patients who can not undergo a major surgery.
2.

Staged: patients who would tolerate a radical total mesorectal excision (TME) operation, but in whom, because of comorbidities, the morbidity/mortality rate would be significantly increased.
3.

Elective: good operative candidates who have had impressive downstaging or refuse radical surgery.

For the staged/elective groups, if the pathology is ≥ypT3 or N+, radical surgery is recommended.

Equipment

Operating rectoscope: It is 4 cm in diameter and either 12 or 20 cm in length, with a beveled or straight-faced end. The surgeon’s end has an airtight faceplate with four ports sealed by capped rubber sleeves through which the optical stereoscope, suction, and two long-shafted instruments are inserted. The rectoscope and its attachments are secured to the operating room table using a Martin arm. The straight-faced rectoscope is utilized for low tumors to avoid loss of the pneumorectum, and it allows the surgeon the benefit of the improved optics for this low level (Fig. 22.2).

Fig. 22.2

a TEM rectoscope. b Insertion of TEM rectoscope. After gentle dilation of the anus, the rectoscope is inserted with an obturator in place for an atraumatic entry
Stereoscope: The surgeon can visualize the field through the binocular stereoscopic eyepiece, which provides a precise three-dimensional view of the operative field with up to sixfold magnification. The stereoscopic eyepiece itself includes dual lenses, an insufflation channel, and lens irrigator. An accessory monocular scope is connected to a video screen (Fig. 22.3).

Fig. 22.3

a Finalized assembly of the TEM rectoscope. b The four pieces of tubing are connected into their respective ports in the apparatus. The four ports are used for suction 1, continuous insufflation 2, irrigation 3, and the light source 4. The connectors are all different to avoid attaching the tubes to the wrong location
Long-handled instruments: All operating instruments are 5 mm in diameter and include graspers, scissors, monopolar cautery hook, needle driver, and clip applier. The graspers are either straight or more commonly angled at the tip. This allows an increased range of grasp by rotating the handle of the instrument (Fig. 22.4).

Fig. 22.4

a Important TEM instruments. From top to bottom: curved monopolar grasping forceps for left and right hands, straight monopolar grasping forceps for left and right hands, suction tube, suture clip forceps, articulated monopolar knife, and straight monopolar knife. b Close-up of curved forceps. c Close-up of straight forceps
Endosurgical unit: This unit provides a light source, carbon dioxide (CO₂) insufflation, suction, irrigation, and continuous monitoring of intrarectal pressure. Simultaneously, an integrated roller pump provides constant low-volume suction at the same rate as the gas insufflation. This permits adjustable effective suction that does not collapse the lumen. The insufflation allows for stable gas pressure in order to maintain visualization of the distended rectum without insufflation of the more proximal colon. Most importantly, this avoids the ballooning effect of using a standard laparoscopic insufflation that turns on and off every few seconds.

Operative Technique

It is essential that the position of the patient is known before surgery. This is because the TEM equipment reach is limited to the bottom 180° of the field of vision. The preoperative rigid sigmoidoscopy is used to localize the tumor and determine the quadrant location of the tumor in order to plan the operative positioning of the patient to allow the lesion of interest to lie at the 6 o’clock position. Patients with an anterior-based lesion are positioned in the prone jackknife position, while those with a posterior lesion are positioned in lithotomy (Fig. 22.5). Laterally located lesions are best approached with patients in the appropriate lateral decubitus position.

Fig. 22.5

Prone position: ideal for patients with anteriorly located lesions. The arms are resting without straining on arm boards

All patients receive a mechanical bowel preparation the day before surgery, as well as preoperative antibiotic prophylaxis. TEM is performed under general anesthesia, and a Foley catheter is inserted in all patients.

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