Several techniques of EMR have been introduced including the injection-assisted technique, the cap resection technique, and the ligate-and-cut technique (Fig. 11.3) .

Injection-assisted EMR starts with injection of a solution into the submucosal layer under the lesion, creating a “safety cushion.” This cushion lifts the lesion to facilitate its removal and prevent complications such as perforation caused by mechanical and electrocautery damage to deeper layers. A polypectomy snare is used through a single-channel endoscope to snare the lesion (Fig. 11.3a). The injected solutions, especially normal saline, spread out into the submucosal space within a few minutes and repeat injections may be required for successful EMR. In addition, the marking of the target tumor margin using electrocautery may be considered to identify the accurate resection margin after the submucosal injection changes the shape of the lesion.

The strip biopsy technique was developed as an application of injection technique. In this method, a double-channel endoscope is used in order to snare the lesion while it is grabbed and pulled toward the endoscope with a grasper [32] (Fig. 11.3b). As a variation of this technique, Kondo et al. reported EMR of large gastric lesions with countertraction of the lesion by grasping forceps placing through a percutaneous gastrostomy [33].

Currently, the endoscopic cap resection technique (EMR-C) and the endoscopic ligate-and-cut technique (EMR-L) are commonly performed in the USA. Between these techniques, a randomized trial has demonstrated similar efficacy and safety for EMR of early-stage esophageal cancers [34]. EMR-C also uses submucosal injection to lift the target lesion. Dedicated mucosectomy devices that use a plastic cap with rim and a specialized crescent-shaped electrocautery snare have been developed [35]. The snare must be opened and placed on the internal circumference rim at the tip of cap, which is attached on the end of the forward-viewing endoscope. Once the endoscope is positioned over the lesion, suction is applied to retract the lesion into the cap, and the snare is closed to capture the base of the pseudopolyp. The lesion is then resected with a standard snare excision (Fig. 11.3c). Different sized and shaped caps are available based on the tumor size and location (Fig. 11.4). The straight caps are commonly used for the lesions in the stomach and colon and the oblique-shaped caps are usually used in the esophagus where a tangential approach is often required [35] .

EMR-L uses a cap attachment with band ligation device (Fig. 11.3d). The device is positioned over the target lesion with or without prior submucosal injection. Suction is applied to retract the lesion into the cap and the band is deployed underneath it creating a pseudopolyp. The pseudopolyp is then resected at its base with an electrocautery snare [36]. The band has enough contractile force to squeeze the mucosal and submucosal layers, but it is not strong enough to capture the muscularis propria. A multiband ligation system was developed to avoid the repeated withdrawal and insertion of the endoscope for band ligation and subsequent resection (EMR-MBL). In our practice, a multiband mucosectomy device (Duette^TM, Cook Medical Inc., Bloomington, IN) is commonly used (Fig. 11.5). This device includes a specially designed six-band ligator, through which a polypectomy snare can be passed, and the band ligation and subsequent resection can be performed in series without withdrawal of the endoscope.

The advantages of EMR-C and EMR-L/EMR-MBL techniques would be their simplicity, which only requires the use of a standard endoscope. However, the limitation of EMR is that it cannot be used to remove en bloc lesions larger than 2 cm. Again, piecemeal resection for lesions larger than 2 cm leads to a higher risk of local recurrence and insufficient pathological staging [31, 37]. Thus, a technique to remove larger lesions en bloc was developed [38, 39].

ESD was developed in Japan for en bloc removal of lesions larger than 2 cm in diameter [38–40]. It is an advanced endoscopic resection technique, which involves direct dissection of the submucosal layer using a specialized needle knife. Since the first introduction of ESD using an insulation-tipped knife in Japan [39], various types of needle knives have been developed and introduced into practice (Fig. 11.6). En bloc resection of lesion allows more accurate pathological evaluation of the lateral and radial margins and reduces the risk of local recurrence [41, 42]. ESD requires several steps, and only carbon dioxide insufflation should be used (Fig. 11.7). First, the margin of the lesion (normal mucosa around the lesion) is marked by electrocautery, which is critical for the success of en bloc resection of large lesions. Then, submucosal injection is used to lift the lesion. In practice, it is preferred to use sodium hyaluronate solution (approximately 0.5 % solution) mixed with epinephrine (0.01 mg/ml) and indigo carmine (0.04 mg/ml), which remains in the submucosal space for a longer period compared with other solutions such as saline and glycerol [43, 44]. Next, the mucosa is incised for a distance of 5 mm outside of the radial margin markings using a needle knife. Once the access to the submucosal space is created, appropriate tension and counter-tension are maintained using cap placed on the insertion tube of the endoscope, which is inserted into submucosal space. The dissection is performed using a needle knife by dissecting submucosal tissues and bridging vessels within the submucosal space. Large vessels should be cauterized using hemostatic forceps. At the completion of the procedure, the lesion should be removed en bloc regardless of its size, preserving a thin layer of submucosa (sm3) overlying the muscularis propria. Hemostasis should be completed by coagulating visible vessels with hemostatic forceps to prevent post-procedure bleeding. To maintain adequate countertraction between the mucosal–submucosal complex and muscularis propria, it is important to consider how to make the initial mucosal incisions. Partial mucosal incisions should be made first at the most proximal and distal aspects of the tumor; a submucosal tunnel is then created, thereby linking these two openings and exploiting the added countertraction offered by the intact mucosa on the sides flanking the tunnel. The flanking mucosa is then cut, thereby freeing the tumor. It is important to work from proximal to distal locations so that the dissected portion of the tumor can be “pulled” out of the way by gravity .