The TEM procedure is traditionally performed under general anaesthesia, although since about 2 years we adopted spinal anaesthesia as a standard with no exclusion criteria [24]. The patient is placed either prone or supine in order to keep the lesion as close to the 6-o’clock position as possible, even with lateral lesions. Different from the technique originally conceived by Buess, we avoid placing the patient in the lateral decubitus position, as this is extremely difficult and the benefit is minimal. Patients with lateral lesions are usually placed in the supine position, unless the lesion is predominantly located in the right or left upper quadrant (i.e. 12- to 3-o’clock position or 9- to 12-o’clock position). With circumferential lesions, the patient is always positioned prone due to the higher risk of entering the peritoneal cavity and the consequent need to reduce the descent of small bowel loops into the surgical field while repairing the opening itself.

Patients are mobilised the same day as surgery. The urinary catheter placed at the time of surgery is removed 24 h after surgery (48 h if the anterior wall was involved). Postoperative analgesia is ensured by intravenous paracetamol for 24 h. Oral intake is allowed the day after flatus is reported.

With the advent of endoscopic submucosal dissection (ESD) about 15 years ago, flexible endoscopy permitted a surgical-like technique for en bloc resection of superficial lesions of the digestive tract. First indicated for the upper gastrointestinal tract [25], ESD then was applied to the lower gastrointestinal tract with promising results [26]. Although ESD represents an alternative to endoscopic mucosal resection (EMR) of the colon, its application to the rectum can be compared with TEM, aiming to achieve en bloc R0 excision. A meta-analysis [27] including 11 ESD and 10 TEM series (2,077 patients in total) showed that the en bloc resection rate was 87.8 % (95 % confidence interval [CI] 84.3–90.6) for the ESD patients versus 98.7 % (95 % CI 97.4–99.3 %) for the TEM patients (P < 0.001). The R0 resection rate was 74.6 % (95 % CI 70.4–78.4 %) for the ESD patients versus 88.5 % (95 % CI 85.9–90.6 %) for the TEM patients (P < 0.001). The postoperative complications rate was 8.0 % (95 %, CI 5.4–11.8 %) for the ESD patients versus 8.4 % (95 % CI 5.2–13.4 %) for the TEM patients (P = 0.874). The recurrence rate was 2.6 % (95 % CI 1.3–5.2 %) for the ESD patients versus 5.2 % (95 % CI 4.0–6.9 %) for the TEM patients (P = 0.068). Nevertheless, the rate for the overall need of further abdominal treatment, defined as any type of surgery performed through an abdominal access, including both complications and pathology indications, was 8.4 % (95 % CI 4.9–13.9 %) for the ESD patients versus 1.8 % (95 % CI 0.8–3.7 %) for the TEM patients (P < 0.001). Despite the retrospective nature of the studies included, TEM seems to be able to warrant better oncologic results compared to ESD, with similar complication rate. The major advantage advocated by flexible endoscopists is the avoidance of general anaesthesia for ESD technique. We recently collected data of a series of 50 patients who underwent TEM under spinal anaesthesia showing promising results [24]. No intraoperative complications occurred, and operative time was comparable to the procedure performed under general anaesthesia. The need of opioids in the operating room and in the postoperative time was very low, and median postoperative pain assessed by VAS was 0 (range, 0–3) at 4 h, 0 (range, 0–2) at 8 h, 0 (range, 0–2) at 24 h and 0 (range, 0–1) at 48 h. TEM is safe and feasible under spinal anaesthesia and in selected cases will probably become a 1-day surgery procedure. It should be kept in mind that ESD is a long-lasting procedure (many hours) requiring long-lasting sedation and is probably less comfortable for the patient than a spinal anaesthesia. Moreover, due to the low accuracy of the preoperative staging, a full-thickness R0 resection is advisable, and TEM is probably nowadays the best technique to reach this goal in the rectum.

Transanal minimally invasive surgery (TAMIS) was introduced as an alternative to TEM in 2010. TAMIS is defined as the use of any multichannel port (single port) transanally, combined with the use of ordinary laparoscopic instruments, a laparoscopic camera lens and a standard laparoscopic CO2 insufflator for the purpose of performing endoluminal or, more recently, extraluminal surgery (Fig. 4.6). A systematic review summarised the existing literature on TAMIS [28]. Since the inception of TAMIS in 2009, 33 retrospective studies and case reports and 3 abstracts have been published, including 390 TAMIS procedures for local excision of rectal neoplasms from 16 countries. The average size of the lesions resected was 3.1 cm, and the mean distance to the anal verge was 7.6 cm. Overall margin positivity rate was 4.36 % and mean operative time was 76 min. Only 9 out of 390 excisions (2.31 %) could not be completed with TAMIS and required conversion to TEM or a laparoscopic abdominal approach. The average length of stay was 2 days; the overall complication rate was 7.4 %. A full-thickness excision was performed only in 60.6 % of the publications reviewed; inadvertent peritoneal entry during TAMIS was reported on four cases (1.025 %); in two cases the closure was done transanally. Peritoneal entry during TEM can usually be managed transanally with full-thickness suture closure by experienced operators. A recent publication of a high-experienced group [29] strongly underlines how, in rectal lesions located in the upper rectum, TAMIS was associated with a high risk of complicated peritoneal entry requiring conversion to a rigid platform. Peritoneal entry occurred more frequently during TAMIS (66.7 %) and resulted in critical loss of pneumorectum and collapse of the rectum precluding adequate suture closure. All cases were salvaged by replacing the TAMIS platform with the 12.5-cm-long rigid TEO platform, effectively stenting the rectum open up to the level of the rectal defect, which permitted adequate suture closure of the defect. There is another important limitation of this platform, due to the shape of the single port. With rigid platforms (TEO or TEM), low rectal lesions close to the dentate line can be excised with high precision and stability of the device. The single port used in TAMIS procedure must be placed inside the anal canal, with the proximal edge of the device overcoming the anal sphincter, this way making impossible the access to the lower 5–6 cm of the rectum. Considering both technical limitations, it can be argued that TAMIS is probably a useful and safe technique only for middle rectal lesions, not being able to get access to the lower rectum and not being able to maintain a stable operating field if a peritoneal opening occurs in excising upper rectal lesions (Figs. 4.4 and 4.5).

Furthermore there are many concerns regarding the efficacy of this platform in the most challenging phase of a transanal operation: the suture of the rectal wall. In 2013 we published a pilot study assessing the feasibility and efficacy of TAMIS in an ex vivo model compared to TEM [30]. In a dedicated trainer box for transanal procedures, ten surgeons with no experience in transanal surgery were asked to perform a dissection/suture task using both TAMIS and TEM in randomly allocated order. Dissection and suturing were significantly quicker in the TEM group. In three cases in the TAMIS group, completing the suture was not considered possible, and the procedures were terminated by TEM. Subjective evaluation revealed a better appreciation of TEM in all proposed comparisons: dissection, suturing difficulty, quality of vision and instrument conflicts, concluding that both techniques were comparable for achieving a good dissection, although TAMIS failed to prove effective in suturing the rectal wall.

To overcome this limitation, some authors proposed a robotic TAMIS with the da Vinci system. Hompes et al. [31] showed how robotic TAMIS can be performed using a glove port in a series of 16 patients. Atallah et al. [32] reported a series of 18 robotic TAMIS procedures including complex fistula repair and transanal total mesorectal excision, showing the feasibility of this complex operation. Further research with robotic transanal approaches is necessary to determine whether or not this approach can provide patients’ significant benefit.

Last but not least is a consideration about costs. Mark Whiteford, Director of the Colon and Rectal Surgery Unit at the Oregon Clinic, presented during the European Colorectal Congress in 2014 a cost analysis comparing TEM and TAMIS. With a case load of 30 procedures per year, TAMIS is much more expensive (about 11,400–38,000 € per procedure) compared to TEM (about 3600–6600 € per procedure).

Nowadays we can state that local resections performed with TAMIS platform are feasible, but the device has many limitations and is not cost-effective compared to TEM. Randomised controlled trials are needed to really define the real usefulness of TAMIS.

Low accuracy of preoperative staging is the biggest issue in properly selecting patients suitable for TEM. T1 tumours invading the rectal wall more than 1 mm in the submucosa (T1 sm2-3) and T2 tumours have a risk of lymph node involvement up to 25 %, which imposes a further TME. TME after full-thickness TEM is a challenging operation, with a significantly higher risk of APR compared to primary TME [33]. After a full-thickness TEM, the primary tumour is completely excised, and the patient has a probability of 75 % or more to have been cured by the transanal procedure alone. So it would be advisable to find a way to warrant the complete ‘sterilisation’ of the mesorectum, in order to kill metastatic lymph nodes and improve the oncologic outcome of local excisions.