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Shichijo et al. Mini-invasive Surg 2022;6:19 https://dx.doi.org/10.20517/2574-1225.2021.121 Page 9 of 13

Impact of underwater EMR
Small lesions (≤ 15 mm) with submucosal fibrosis, and small local residual or early recurrent carcinomas
after endoscopic resection, which are difficult to be removed by conventional EMR and are indications for
ESD, can be managed also by underwater EMR [3-5,79] . Furthermore, lesions sized 20-30 mm , and lesions
[80]
[79]
slightly invading the submucosal layer (T1a) can also be managed using underwater EMR . Therefore, the
“true” indication for ESD is geared toward larger lesions, for which ESD harbors higher risk; this review
could aid in guiding ESD for those lesions.

Full thickness resection
Endoscopic full thickness resection for gastric submucosal tumors, especially for gastrointestinal stromal
tumors, is performed in several countries [81-83] . As for colon, the novel OTSC, a full-thickness resection
device (FTRD, Ovesco Endoscopy, Tübingen, Germany), was first introduced in 2011 . Hundreds of
[84]
patients were treated by FTRD, and endoscopic full-thickness resection for nonlifting, invasive lesions in the
colon and rectum appears to be effective and safe . Although nonlifting lesions indicated for FTRD can be
[85]
removed by underwater EMR, invasive lesions, especially invasive to deeper layers, such as muscle layers are
almost impossible to be removed by EMR or ESD.

Future trends
ESD using a CO laser has been reported in vivo and ex vivo (porcine colon tissue) . Because saline or
[86]
2
sodium hyaluronate solution injected into the submucosal layer during ESD procedure has a high
absorption coefficient at the wavelength of the CO laser, safer ESD is expected with a CO laser with less
2
2
thermal damage to tissue.
An endoscopic device for colonic submucosal dissection using a combination of bipolar radiofrequency and
microwave modalities has also been reported in a porcine model . Currently, ESD can be performed only
[87]
by experienced endoscopists, but with the advancement in devices and techniques, more widespread use
could be facilitated.

Robot-assisted ESD is also attempted in a porcine model [88,89] . With two hands available like surgery, more
efficient resection can be achieved. Shorter procedure time and less complication are reported by ESD
novices, and robot-assisted ESD is also associated with lower physical and mental workloads.

CONCLUSION
With the development of various instruments and techniques, ESD has become more common and safer.
However, because ESD sometimes leads to deleterious complications, the indications for ESD should be
carefully considered.

DECLARATIONS
Authors’ contributions
Drafted the manuscript: Shichijo S
Critical revision and final approval of the article: Takeuchi Y

Availability of data and materials
Not applicable.

Financial support and sponsorship
None.