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A transparent tip hood (Elastic Touch; Top, Tokyo, Japan) is always used to facilitate traction application
on the mucosa when creating space for submucosal dissection with carbon dioxide insufflation. Sodium
hyaluronate solution (0.4%; Muco Up; Johnson & Johnson, New Brunswick, NJ, USA) with 0.5 mL of indigo
carmine and 0.1 mg of epinephrine is injected into the submucosal layer using a 21-gauge injection needle.
It might be useful to have a traction device (such as an S-O clip; Zeon Medical Co., Tokyo, Japan) as well, if
needed.

TIPS ON HOW TO USE THE SB KNIFE JR FOR COLORECTAL ESD
Colorectal ESD using the SB Knife Jr does not require simultaneous complex endoscopic movement while
applying an electric current; therefore, it can be performed relatively safely and easily. However, the
fundamental operating technique is quite different from conventional knives (i.e., needle-type knives).
Therefore, it is necessary to be familiar with the characteristics of the SB Knife Jr for colorectal ESD.

Treatment strategy of colorectal ESD using the SB Knife Jr
The endoscopic position during the procedure is kept in a forward view, not using a retroflexed position,
[5]
and then a circumferential incision and dissection are performed from the anal side . In cases with a large
lesion, a proximal incision is made to define the end and guide the circumferential incision. Following that,
the treatment strategy of colorectal ESD using the SB Knife Jr is the same as that using conventional knives,
such as the mucosal-flap method, tunneling method, and pocket-creation method.

The following are some useful tips for incision and dissection using the SB Knife Jr: perform the
circumferential mucosal incision similar to cutting paper and the submucosal dissection the image of
“connecting the dots at the appropriate dissection depth” . The basic colorectal ESD procedure using the
[13]
SB Knife Jr consists of the following three steps, and a circumferential incision, submucosal dissection, and
hemostasis can all be performed using a single device.

The three basic steps for ESD procedure using the SB Knife Jr [Figure 3]
Step 1: grasping
The target tissue is approached and grasped with the SB Knife Jr as in the biopsy technique. Inadvertent
resection can be avoided by regrasping, which ensures safety. In the case of severe fibrosis of the target
tissue, the scissors are closed slowly to facilitate grasping. In situations wherein it is difficult to manipulate
the scope, the scope position should be fixed while simply inserting and pulling the SB Knife Jr (not moving
the scope, moving the knife only). With more experience, the endoscopist can control the opening of the
knife to open slightly to grasp even single-strand fibers.

Step 2: pulling
The safety of the ESD procedure can be ensured by pulling the SB Knife Jr slightly forward and away from
the muscle layer while grasping the target tissue to avoid electrical damage to the muscle layer. With
experience and when the lesion is sufficiently elevated by submucosal injection, it becomes possible to skip
the pulling step and move on to the third step of cutting the grasped tissue using an electric current, which
can speed up the procedure considerably.

Step 3: cutting
After confirming that the SB Knife Jr does not grasp the muscle layer together, the cutting electric current is
applied, and the grasped tissue is incised. Even if there are small blood vessels within the tissue,
intraoperative bleeding usually does not occur. However, if the tissue contains large blood vessels, applying
the coagulation electric current as prophylactic hemostasis for about 1 s twice before attempting incision