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INTRODUCTION
There are some important factors that make endoscopic submucosal dissection (ESD) difficult such as the size of the tumor, fibrosis, bleeding, etc. However, the main factors that make ESD difficult are absence of counter traction and poor field of vision. Good counter traction allows for safe and speedy dissection. The key points to maintaining a good field of vision and counter traction are described in this paper.
POSITION CHANGE
The simplest method to get counter traction is position change. If the location of a lesion is situated so that gravity does not aid in the removal of blood and water, good counter traction cannot be obtained, and sometimes water and blood will interfere with the surgeon's field of vision. However, if the lesion is positioned to use gravity to keep the field of vision clear of blood and water the surgeon will have a clear field of vision. Additionally, gravity can be used to pull the mucosa which gives the surgeon adequate counter traction and further assists in creating a clear field of vision. Therefore, the patient should be positioned to make effective use of gravity during ESD.
Clip with sinker method increases the effects of gravity.1 A clip with sinker was attached to a target site at the edge of the exfoliated mucosa after circumferential mucosal incision. Then the weight of the sinker pulled down the partly resected mucosa allowing for good counter traction.
CLIP WITH LINE METHOD
If you can pull the target lesion, good counter traction can be made. The authors reported clip with line method in 2002.2
Figs. 1, 2 are reprints from the paper by permission of the publisher. It is a simple and useful method to make counter traction during ESD. A long, 3-0, silk line was tied to the arm part of the clip (HX-610-135; Olympus, Tokyo, Japan) (Fig. 3). Then the clip with line is reset in the cassette (Fig. 4).
The scope is withdrawn when the circumferential incision is finished (Figs. 5, 6). A clip applicator device (HX-110QR; Olympus) is inserted into the accessory channel of the endoscope, and the clip with line is mounted onto the tip of the applicator. Then the clip was drawn into the applicator device, and the applicator device is also drawn into the transparent hood for insertion into the endoscope.
The scope is inserted again, and the submucosal side of the target lesion is grasped (Fig. 7). After that the line is pulled very gently. Only a small amount of tension is required to create counter traction. This method also creates a clear field of vision (Figs. 8, 9). During submucosal dissection, tension is maintained with a 10-g sinker such as mouth piece. The 10-g sinker creates sufficient counter traction and tension without threatening to tear the submucosal layer.
If you want to pull the line to anal side, the pulley method is useful (Fig. 2). A second clip is inserted and opened just before the line. The line was captured by the second clip and fixed at the opposite side of the stomach. Then, the first clip could be pulled to the anal side with the second clip acting like a pulley. Recently, similar ideas have been reported from Asian endoscopists.3-5
The clip with line method is a simple and useful method not only for gastric ESD, but also for esophageal, colonic, and duodenal ESD.6 It is especially useful for esophageal and gastric ESD when the cancer exists in the greater curvature of the gastric body.
EXTERNAL GRASPING FORCEPS METHOD
The external grasping forceps are captured by the other grasping forceps inserted into the working channel. The external grasping forceps are inserted with the help of the other grasping forceps after the circumferential mucosal resection. After the external grasping forceps are anchored at the margin of the lesion and the second grasping forceps are released. The distance from the tip of the endoscope to the dissected site can be adjusted by not only pulling but also by pushing the grasping forceps. Then good counter traction can be made.7,8 Great care was taken to avoid injuring the mucosa, especially at the esophagocardial junction.
INTERNAL TRACTION METHOD
Some methods to make internal traction have been reported. It is different from the clip with line method, in that a set of two clips connected by a rubber ring or nylon line was used. The first clip with rubber ring or nylon line was attached at the target part after circumferential mucosal incision.9,10 After that, the second clip was attached at the opposite sides of the lesion. This pulls up the lesion and opens up the resection margin. This makes submucosal dissection easier. It is a simple and easy method, but the control of the traction power is sometimes difficult.
DOUBLE CHANNEL SCOPE METHOD
A grasping forceps inserted into a channel of a double-channel scope can make counter traction during ESD.11,12 An outer sheath of an injection needle is also useful to make counter traction.13 The bottom of the dissected mucosal layer was pushed and lifted up using the injection sheath to reveal the submucosal layer and to ensure adequate counter traction of the cutting lines.
The advantage of this method is that it requires only a conventional grasping forceps or injection sheath. The disadvantage of double channel scope method is thicker size and long radius of curvature. Additionally, it is sometimes difficult to insert it into submucosal layer, and maneuverability is poorer than a thin therapeutic scope during ESD.
CONCLUSIONS
The key point to make ESD safer and faster is creating a clear field of vision. A transparent hood is necessary to maintain visualization during ESD. A strategy to maintain a clear field of vision is also necessary for safe ESD. There are some methods that create adequate counter traction. Position change and clip with line method are the simplest and easiest methods.
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