Page 48 - Read Online

Page 2 of 9 Yoshizaki et al. Mini-invasive Surg 2022;6:17 https://dx.doi.org/10.20517/2574-1225.2021.116

INTRODUCTION
Thanks to the development of endoscopic techniques, a wide variety of colorectal tumors can be treated
endoscopically. In particular, endoscopic submucosal dissection (ESD) techniques have made remarkable
progress in the past decade. However, ESD is a time-consuming and costly procedure, and its indications
must be carefully considered. Some lesions can be adequately treated with endoscopic mucosal resection
(EMR), and some large lesions are acceptable for endoscopic piecemeal mucosal resection (EPMR) because
they are adenomas. However, cancerous lesions need to be resected en bloc, which is sometimes difficult to
[1]
perform with EMR. The indications are described in detail in the guidelines . This review discusses tips for
difficult cases of colorectal ESD.

ABOUT COLORECTAL ESD
Basics and quality control of colorectal ESD
ESD is a challenging technique, but it is possible to perform en bloc resection regardless of the size,
morphology, or area occupied by the lesion. Thanks to the development of local injection agents that
[2,3]
maintain good mucosal distension and devices suitable for colorectal ESD , ESD can be performed even in
the colon with thin walls and many flexures. The blood vessels of the gastrointestinal tract penetrate the
muscularis propria to form a vascular network in the middle submucosa. Dissection between this vascular
network and the musclaris propria is efficient because there are the fewest vessels to cut. Furthermore, the
safest and highest quality ESD is performed with the least thermal damage to the muscle layer and lesion. A
sufficiently thick resection specimen collected by this method allows for accurate depth of invasion,
lymphovascular invasion, and budding grade. Any ESD device can be used, but the quality of dissection and
the specimen must be ensured .
[4]
ESD results
[5]
In a multicenter study conducted in Japan, the en bloc resection rate of colorectal ESD was 94.5% .
Perforation is a full-thickness defect of the muscular layer, and intraoperative perforation occurred in 2.6%-
[6,7]
4.9% of cases, 96% of which healed conservatively with clip sutures . Endoscopic closure using over the
scope clip or polyglycolic acid sheets for perforation has also been reported . Postoperative bleeding
[8,9]
occurred in 1.5%-4.7% of patients [6,10,11] . The long-term outcome of patients with curative resection is
good . The recurrence rates were 0%-2% for ESD and 12.1%-14% for EPMR [13,14] , and EPMR for early
[12]
[15]
colorectal cancer has a high recurrence rate in the resection of more than five specimens . There have been
cases of recurrence as advanced cancer , thus EPMR should be avoided as much as possible. Recently, it
[16]
has been shown that local recurrence occurs due to tumor implantation. Colorectal tumors are fragile, and
many tumor cells were found floating in the intestinal tract after colorectal ESD . It is important to clean
[17]
the intestinal lumen and ulcer bed thoroughly with water (> 1000 mL) after ESD .
[17]
DEALING WITH DIFFICULT CASES
Difficult factors of ESD
Difficult cases can be divided into two groups: cases in which dissection of the lesion is difficult and cases in
which the approach to the lesion is difficult. The former includes cases prone to bleeding, cases with fibrosis
in the submucosa, and cases with abundant fat. The latter includes cases of poor scope operability due to
adhesions, lesions located at the back of the folds or in the flexure, and lesions on the ileum or anal canal.

Dealing with cases of difficult dissection
Bleeding control
There are individual differences in the easy bleeding and the difficult hemostasis. It is necessary to perform
the technique faithfully to the basics. It is also important to decide whether to pre-coagulate with forceps
based on the easy bleeding in the early stages of treatment. Pre-coagulation is also effective in forced