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Page 2 of 4 Aubert et al. Mini-invasive Surg 2019;3:34 I http://dx.doi.org/10.20517/2574-1225.2019.46

9.5% of patients who underwent TaTME when compared with 3.4% of patients undergoing laparoscopic
TME. Besides this increased rate, a new pattern of local recurrence in terms of its multifocality as well as
its early timing after TaTME has been observed. Regarding these alarming data, the Norwegian surgical
[6]
community decided to cease performing TaTME for low and middle rectal cancer . Today, long-term
results from the international registry of TaTME as well as those from the Dutch survey are not available.
We can imagine that, according to the further results of these two registries, the opinion of the colorectal
surgeon community will definitely be modified. In such an alarming situation, it will probably mean that
TaTME should not be proceeded in non-expert centers.

However, possible problems of TaTME concern not only oncologic results, even if they are the most
important. Some intraoperative adverse events have also been reported during the transanal phase, such
as wrong dissection plane, organs injury (vagina, urethra, bladder, and rectum), and carbon dioxide
[7]
embolism. In the international registry of TaTME including 1594 procedures , 31% of the patients
presented with intraoperative adverse events during the transanal phase mainly represented by technical
problems (18%), wrong dissection plane (6%), pelvic hemorrhage (4%), and organs (urethral, rectal,
vaginal, or bladder) injuries (2%). As a new surgical procedure, the learning curve of TaTME is real, and its
implementation seems to be possible only in high volume centers. In our experience of the 34 first TaTME
cases, intraoperative complications occurred in 21% of patients (4 rectal, 1 bladder, and 1 vaginal perforations)
[8]
vs. only 6% from control cases with standard laparoscopic TME (2 rectal perforations) (P = 0.07) . In
[9]
addition, Perdawood et al. reported bladder and urethral injury in 2% and 1% of their patients, respectively,
and bleeding in 8%. All these intraoperative adverse events occurred during the transanal phase. In our
preliminary experience, when we compared the first 20 cases with the last 14 cases of TaTME, intra-
[8]
operative complication rate, although not significant, decreased from 25% to 14% (P = 0.4) . The American
[10]
training program reported the experience of surgeons after a two-day, cadaver-based training, with
many concerns about wrong dissection plane in 60%, organ injury (especially urethral lesion) in 25%,
and hemorrhage in 15% of cases. This cadaver-based training should be complemented by other training
[10]
[11]
sessions to safely perform TaTME . In addition, Koedam et al. reported in their study that the learning
curve is about 138 TaTME. At the beginning of their experience with their first 40 patients, the rate of
major postoperative complications (Dindo III-IV) was 47.5% of patients, in whom 27.5% was leakage
(anastomotic leakage after restorative surgery and presacral abscesses in patients with a colostomy). These
rates decreased in the second part of the learning curve, but the procedure was still challenging. Forty
procedures may be considered as a cut-off to appreciate an improvement in postoperative morbidity. In
conclusion, the implementation of TaTME seems to be difficult, and the question remains of whether it can
be done everywhere or only in high volume centers.

Carbon dioxide embolism is another intraoperative adverse event reported during TaTME in the literature.
Even if this intraoperative complication is rare, it is well known during minimally invasive surgery [12,13] .
[14]
The first description of carbon dioxide embolism during TaTME was made by Ratcliffe et al. in 2017.
[15]
More recently, Dickson et al. , considering the LOREC (The Low Rectal Cancer Development program)
and OSTRiCh (Optimizing the Surgical Treatment of Rectal Cancer) TaTME registries, reported carbon
dioxide embolism in 0.4% of patients (25/6375). Such occurrence required conversion into open surgery in
7 cases, conversion into abdominal laparoscopic approach in 13 cases, and surgical cessation in 4 cases.
Moreover, postoperative readmission in intensive care unit was necessary in 60% of the cases. Among
the 25 patients with carbon dioxide embolism, postoperative complications occurred in 12 patients (48%)
including 10 major complications (Dindo III-IV: radiological or surgical management of pelvic collections,
renal failure, and pulmonary embolism). Furthermore, carbon dioxide embolism seems to be associated
with venous bleeding, which occurred in 84% of patients. Even if this complication is rare, it appears as a
potentially life threatening complication during TaTME.

During the postoperative course, although the anastomotic leak rate was initially very low in the first
TaTME reports, the rate is now similar to laparoscopic TME. In the international registry, anastomotic