ESD is effective in the treatment of early gastric cancer and precancerous lesions. The key to the success of ESD surgery is submucosal dissection. Good exposure of the operation visual field during submucosal dissection can shorten the operation time and significantly reduce the occurrence of bleeding, perforation and residual tumor tissue. In order to better expose the operational field of vision, various clinical attempts have been made, such as internal traction, external floss or snare traction, magnetic traction, etc. Each method has its limitations. For example, floss traction method, the texture of floss is hard, thin, there may be potential cutting damage to the surrounding tissue; Floss can only pull the lesion towards the oral direction, but cannot push the lesion in the anal direction. In the snare traction method, the snare is rigidly connected with the lesion, which is easy to tear the lesion during the operation, resulting in lesion damage and affecting the postoperative pathological evaluation. Excessive tension caused by excessive tightening of snare can cause leison damage, even bleeding and perforation[1, 8, 9]。
The key points of the snare and rubber band combined assisted traction method: (1) timing of use: in the process of conventional ESD, when the submucosa is not fully exposed, the traction method can be considered. The rubber band connected with the snare was clipped on the lesion at the cut edge with a metal clip, and the snare was pulled to the oral side or pushed to the anal side according to the location of the lesion and the degree of submucosal exposure. (2) The extracorporeal snare and the rubber band should be firmly connected to prevent the rubber band from escaping during the process of conveying to the stomach. The snare connected with the rubber band is tightened on the outside of the transparent cap, but not on the top of the transparent cap, so as not to increase the difficulty of releasing the snare device. (3) When the snare tip reached the vicinity of the lesion, the snare was released carefully and slowly to avoid damage to the lesion. Under endoscopic observation, the metal ring at the front end of the snare was received into the plastic sheath tube, and during tighten the snare metal ring to prevent it from trapping the lesion and surrounding mucosa.(4) During the process of metal clip clamping, the rubber band was moderately pulled so that the middle point of the distal end of the rubber band was clipped on the mucosal surface of the lesion.(5) Although the snare used as traction is connected with the lesion by elastic rubber band ring, it is still not allowed to exert too much force in the process of pulling or pushing, so as to avoid the lesion damage.
The advantages of the snare combined with the rubber band traction method: (1)The required materials are readily available, the snare and metal clips are the common instruments in endoscopic central, and the rubber bands are cheap and available for sale. The operation method is simple and easy to master. (2) The trap appliance has certain hardness, can play a supporting role; The sheath tube of the snare is smooth and the diameter is larger than that of all kinds of traction line equipment, so that there is no cutting damage to the surrounding mucosa; The elastic action of the rubber band makes the pulling force relatively constant, which makes it easier to fully expose the surgical field and reduce the damage to the lesion.(3) Through the aid of the snare, the pull and push traction method can be realized, with flexible operation and stronger practicability. (4) During the process of assisted traction, the traction position of the distal end of snare can be adjusted appropriately through the endoscope, which is more conducive to exposing the surgical field of vision. (5) ESD may operate by only one person. The trap can maintain the current traction state without extra force after pushing or pulling to the appropriate position, so there is no need to be equipped with assistant traction. (6) The excised lesion can be taken out of the stomach directly through the snare-rubber band-metal clip.
In conclusion, the new technique of traction assisted by the snare device and rubber band can provide a good surgical field of view, shorten the operation time, and reduce the incidence of bleeding, perforation and other complications in the ESD of early upper gastrointestinal cancer. For beginners can reduce the difficulty of operation, improve the operator's treatment confidence.