Training in Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection: The Eastern Perspective

Masao Yoshida, MD and Kohei Takizawa, MD

Introduction

Some experts have proposed that endoscopic submucosal dissection (ESD) should be performed after mastering endoscopic submucosal resection (EMR).¹ However, en bloc EMR can sometimes be technically more difficult than ESD depending on the location and size of the lesion. Furthermore, scope manipulation and maneuvers are quite different between EMR and ESD. With the advent and rapid growth of submucosal endoscopy, including techniques such as per-oral endoscopic myotomy, laparoscopic and endoscopic cooperative surgery, and submucosal tunneling endoscopic resection, many operators are becoming trained in these advanced procedures without the prerequisite expectation of mastering EMR. Given that both EMR and ESD are intrinsically different techniques, we believe that each deserves its own dedicated independent training. In this chapter, we describe training methods for both EMR and ESD separately and discuss future directions from an Eastern perspective.

Endoscopic Mucosal Resection Training

We frequently have opportunities to diagnose and treat colorectal lesions in clinical practice. Hence, it is important for trainees to master EMR for the management of colorectal lesions. Colorectal EMR is more challenging when compared with other gastrointestinal locations, including the esophagus and stomach. Thereby once trainees have acquired EMR techniques for colorectal lesions, it would be easier to perform EMR in other parts of the digestive tract. In this section, we describe training in colorectal EMR.

In general, lesions < 10 mm in size and located in the 4 to 8 o’clock visual field without endoscopic torqueing are optimal for beginners. After careful lesion characterization, trainees should focus on rotating the lesion to the 6 o’clock direction and stabilize scope positioning. Once the endoscopic visual field is stabilized and maintained, EMR can be carried out by performing a series of steps (ie, submucosal injection, snaring, resection), which are discussed in Chapter 5. The initial step of scope stabilization to position the lesion in the optimal field of view for resection is the most challenging maneuver to master. However, unless this technique is acquired, it is difficult to complete the EMR and confidently confirm that no residual tissue remains, which can contribute to unsatisfactory R0 (complete) resection rates. Since the position of the scope accessory channel is different between the colonoscope and esophagogastroduodenoscopy, operators should adjust the field of view accordingly.

Once trainees are able to successfully position and maintain any lesion in the 6 o’clock field of view, they should be able to proceed with the resection of larger lesions or those located between folds.

Similarly, the fundamental of scope positioning and stabilization prior to endoscopic resection is also crucial for safe and effective ESD in any part of the digestive tract.

Tip

Aim at positioning the lesion of interest to the 6 o’clock position in the field of view on a routine basis.

Endoscopic Submucosal Dissection Training

As previously mentioned, training in EMR and ESD can be in parallel. However, given the technical complexity of ESD, this technique should not be initiated by inexperienced endoscopists without any prior background in endoscopic resection techniques. Dutiful preparation is key to minimize potential serious adverse events associated with ESD. We propose important requisites and benchmarks for trainees interested in ESD in the following section.

Preparation to Become Endoscopic Submucosal Dissection Trainees

These listed items should be mastered during self-training and daily practice.

Basic Knowledge

Indications of endoscopic resection (Chapter 3)
- To avoid unnecessary treatment
- To properly manage in case of a noncurative resection
Requisite materials for ESD
Devices and accessories for ESD (Chapter 3)
Electrosurgical equipment and principles (Chapter 4)
Understanding difficult-to-treat lesions (cardia, pylorus, the greater curvature of the upper or middle third of the stomach, ulcerative lesions)
Management of ESD complications (Chapter 7)

Basic Endoscopic Technique

Adequate observation and evaluation before treatment
- To achieve R0 resection
- To avoid unnecessary surgery for ESD-indicated lesions or ESD for ESD-unindicated lesions
- To optimize the field of view of the endoscope prior to resection
- To avoid unexpected moves of electrosurgical ESD knife to the muscle layer
Target biopsy
- To bring the device to the targeted point
- To stop intraoperative bleeding
Emergency hemostasis
- To identify the exposed vessel promptly
- To manage intraoperative and postoperative bleeding
Clip closure and endoscopic suturing
- To manage perforation

Tips

It is surprisingly difficult to bring a biopsy forceps to the targeted area. However, mastery of this maneuver ensures scope stabilization, maintenance of the target lesion in the desired location, and directed therapy (forceps operation). Practicing how to conduct targeted biopsies daily promotes the basic principles necessary to master ESD.

When performing targeted biopsies, try to biopsy precisely within 1 mm from the intended lesion.

Before Starting Endoscopic Submucosal Dissection in Humans

After completing the steps outlined previously, trainees need to conceptualize the ESD procedure and translate this into hands-on practice. The following steps will assist in this process:

Watching a live or recorded demonstration
- To recognize the different gastrointestinal layers, particularly the submucosal space and the underlying muscle layer
Participation in a hands-on seminar or exercise using an animal model
- To learn basic usage of the ESD devices and accessories
- To reinforce ESD knowledge and translate this into hands-on practice

Learning Endoscopic Submucosal Dissection

Training in ESD in the East generally involves starting with gastric lesions in the antrum, particularly given the higher incidence of gastric cancer when compared to Western countries and the relative ease of identifying the submucosal plane in this particular anatomical area.1–3 Alternatively, it is also acceptable to start ESD training in rectal lesions even in Asian countries.⁴ The incidence of gastric cancer will likely decrease in a few decades with eradication of Helicobacter pylori infection. Similar to gastric antral lesions, identification of the submucosal plane is relatively easy in rectal lesions. Furthermore, given the accessibility of these lesions, supervising endoscopists can readily take over in the event of a complication.

In our Eastern experience, trainees begin ESD procedures with the injection and mucosal incision. To ensure the safety of patients during ESD procedures performed by trainees, a supervisor should take over the ESD procedure when any of the following conditions are met: (1) total operation time exceeds 60 minutes; (2) hemostasis required for > 5 minutes; (3) perforation is observed; or (4) at supervisor’s discretion based on clinical assessment. Upon completion of the initial mucosal incision, we recommend the supervising endoscopist to expose the submucosal plane which can be challenging. Once accessed, the trainee can then proceed with submucosal dissection within the readily identified plane. The identification and establishment of the submucosal plane is crucial for safety during ESD and can be further enhanced by providing traction with the dental-floss-with-clip technique.5–7 ESD cases performed by trainees using this ancillary technique have been shown to be favorable as a short- and long-term training strategy.^8,9

Figure 30-1. Relationship between the mean resection speed (minutes/cm²) of trainees and number of procedures. The solid line represents the curve of the best fit for the plots based on the equation from Yoshida et al.⁹ (Reprinted with permission from Yoshida M, Kakushima N, Mori K, et al. Learning curve and clinical outcome of gastric endoscopic submucosal dissection performed by trainee operators. Surg Endosc. 2017;31[9]:3614-3622. doi:10.1007/s00464-016-5393-9.)

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