Endoscopic submucosal dissection techniques using an insulated-tip knife (IT knife) were introduced several years ago to allow en-bloc resection of early gastric cancers, since histological evaluations are essential in order to assess the risk of lymph-node metastasis [1]
[2]. However, the technique requires special skills and involves a prolonged procedural time. We have therefore developed a new type of dissection knife, termed the “hood-knife” (patent pending in Japan), which only requires a simple technique.
The novel, semitransparent hood covers one-third of the tip circumference, facilitating endoscopic hemostatic procedures while simultaneously allowing irrigation of the bleeding site [3]. The hood is easily placed on the tip of the endoscope, although it has to be fitted to the right side of the endoscope. The hood-knife is made by drilling another side hole, in addition to the hole for the irrigation tube, into the cap portion of a transparent end hood. A snare forceps is glued to the exterior surface over the hole and attached using short tubes on the inside of the cap (Figure [1]).
Figure 1 The irrigation hood-knife: a side view, b view from below. The irrigation tube (white arrow) and snare (arrowhead) are glued to the exterior surface over the hole, and the snare is attached using short tubes (black arrows) on the inside of the cap.
The endoscopic submucosal dissection procedure using the hood-knife is carried out as follows (Figure [2]). Marking dots are made on the circumference of the target tumor, outlining the margin of the lesion. After injection of a saline solution into the submucosa, the tumor is separated from the surrounding normal mucosa by complete incision around the lesion using the IT knife. The endoscope is then withdrawn, and the hood-knife is placed on the tip and fixed with tape. A grasping forceps is passed through the accessory channel, and the lesion is pushed away from the muscle layer. Submucosal exfoliation is carried out by sliding the hood-knife with coagulation current along the muscle layer. With this method, endoscopic submucosal dissection can be safely and easily carried out under direct vision.
Figure 2 a Endoscopic submucosal dissection using the hood-knife; a grasping forceps (arrow) pushes the lesion away from the muscle layer, and the hood-knife is slid with coagulation current along the muscle layer. b Schematic representation of the endoscopic submucosal dissection procedure using the hood-knife.
Three specimens were resected in an animal model (pigs). The average diameter of the resected specimens was 30 mm, and the average time required for endoscopic dissection was 3 min. Another advantage of the hood-knife is that endoscopic submucosal dissection and endoscopic hemostasis can be carried out while simultaneously applying adequate irrigation [3]
[4]
[5].
Endoscopy_UCTN_Code_TTT_1AO_2AG
