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Page 6 of 12 De Rosa et al. Mini-invasive Surg 2020;4:34 I http://dx.doi.org/10.20517/2574-1225.2019.53

Finally, the potential for major bacterial contamination as a consequence of the rectal transection, as shown
by Velthuis with 39% of positivity of pelvic culture, suggests the risk for higher rates of pelvic sepsis, but
[41]
this concern was not confirmed by subsequent studies .
Indeed, the literature available reports an average rate of pelvic abscess of 2%-3% [29,42] and more up to date
[33]
review data confirm an overall incidence of 2.2% .
Despite these encouraging results, TaTME has some very specific complications. Rouanet reported urethral
injury in 6.6% of cases; however, this was a series of 30 difficult high BMI male patients, most following
[43]
radiotherapy . However, urethral injury is a serious complication directly related to the transanal phase of
the operation and is very uncommon during open or laparoscopic TME.

In the largest multi-institutional registry reporting on 720 patients, the occurrence of urethral injuries was
0.7% and was associated with bladder injuries, vaginal and rectal perforations, and damage to hypogastric
[29]
nerves .

Another matter of concern specific of this technique is the possibility by pneumo-pelvis of creating a
false dissection plan, misleading the surgeon and increasing the risk of inadvertent damages of sidewall
[29]
autonomic nerves and vessels laterally and of sacral venous plexus posteriorly .
Finally, carbon dioxide embolism during TaTME, a rare but potentially life-threatening complication, was
[44]
reported by Ratcliffe et al. and may occur in up to 0.4% of patients, mandating conversion to open and
[45]
giving rise to postoperative morbidity .
ONCOLOGICAL RESULTS
TaTME was conceived to overcome some of the technical challenges in rectal cancer surgery, enabling
dissection of a high quality mesorectal envelope. Soon after its introduction, several preliminary reports
showed a good quality mesorectum in almost all cases, negative circumferential and distal margins, and a
level of lymph node harvesting comparable with the conventional approach [37,46,47] .

These results are important since an incomplete TME represents an independent risk factor for local
[48]
recurrence, regardless of the achievement of circumferential and distal negative margins .

With an intact mesorectal fascia, the likelihood of local recurrence, even with involved lymph nodes, is
[49]
significantly lower than with a threatened one and is around 7.5% .

Negativity of circumferential margin is another indicator of the quality of the rectal resection and its
[50]
involvement is reported in 8%-10% of cases .
[22]
Fernández-Hevia et al. confirmed this trend by comparing TaTME with laparoscopy in a match-
controlled study showing similar numbers of lymph nodes harvested and negative circumferential margin
in all cases.

Velthuis obtained similar results demonstrating that with a transanal approach a significantly higher rate of
[51]
complete mesorectal excision could be achieved, compared with laparoscopic patients .

In an early meta-analysis reporting data on 510 patients, a complete TME specimen was reported in 88% of
[38]
cases and near complete in 6%, while CRM was positive in 5% of cases and the DRM in 0.3% of cases .