Will conventional endoscopic submucosal dissection disappear or be rescued from the water by saline immersion?

Endoscopic submucosal dissection (ESD) has become a pivotal endoscopic procedure for en bloc resection of superficial neoplastic gastrointestinal lesions [1]. Technical developments have evolved over time to facilitate, accelerate, and improve safety and outcomes of this difficult technique.

“The present study by Ramai et al. might spark a discussion about the future evolution of schools of different ESD techniques: will they merge into a single universal technique, or will they keep their specificities?”

In this issue of Endoscopy, Ramai et al. report the results of their systematic review and network meta-analysis [2] comparing three major techniques of ESD [3]:

1. conventional ESD (C-ESD): the lesion is dissected progressively after (semi)-circumferential mucosal openings;

2. tunneling ESD (Tu-ESD) or the pocket creation method (PCM): one (PCM) or two (tunnel) small mucosal openings are performed with the aim of maintaining scope stability and natural tissue tension under the mucosal roof during the dissection along the plane of the muscularis propria, before opening the lateral sides, starting with the gravity side;

3. traction-assisted ESD (Tr-ESD): after circumferential mucosal opening, traction devices are used to help keep the submucosal plane open, avoiding problems with access, and keeping tissue tension for further smooth dissection.

The reported analysis selected 18 randomized controlled trials from Asia that included 2677 patients, with colorectal ESD performed in half of the studies (9/18).

Overall, the findings demonstrated that:

• Tr-ESD and Tu-ESD outperformed C-ESD in en bloc resection, curative resection, procedure time, and adverse events

• Tu-ESD was superior to Tr-ESD and C-ESD in terms of curative resection

• Tr-ESD was quicker than the other modalities

• C-ESD was associated with more adverse events.

This well-designed study confirms our expert opinion that using pocket, tunneling, or traction methods facilitates ESD. This important information also supports our experience that, when dealing with difficult locations or lesions, the rapid use of these technical tricks benefits our patients and time schedules.

A major issue arising from this research is how to push our young endoscopists to choose the appropriate technique at the start of their ESD training. Another is how to adjust our strategy based on our target: Tu-ESD is preferred when dealing with carcinoma as it is associated with better curative resection rates, and Tr-ESD is preferred to speed up the procedure for benign lesions. Of course, no technique is universal, and experts must be familiar with the advantages and disadvantages of the different ESD techniques.

Two major questions were not addressed by the study. The first question is: can we combine different techniques? Of course, starting with circumferential mucosal incision compromises PCM. On the other hand, traction is becoming more commonly used to facilitate pocket opening at the end of PCM [4]. The second question is: how will these technical comparisons evolve in the new era of “underwater ESD” and the “water-pressure method” [5], more properly named “saline immersion” ESD? Indeed, PCM has progressed to saline immersion therapeutic endoscopy ESD [6], and many endoscopists are now using saline immersion for C-ESD or during Tu-ESD for resecting the gravity side. This facilitates natural “specimen traction” by taking advantage of the floating effect related to the liquid environment. This also helps to clarify submucosal visualization, avoiding smoke and fat adherence to the scope lens, and limiting the time and staff workload needed to turn the patient during the procedure. Even Tr-ESD has been adapted to saline immersion when appropriate for the lesion location. A recent systematic review and meta-analysis comparing C-ESD with underwater ESD demonstrated advantages in terms of dissection speed with underwater ESD [7].

We also need to view these data in the context of the rapid technical evolution driven by our industry partners. Advancements are underway to develop new electrosurgical settings for better precision in saline immersion conditions, new enhancement modalities to better see dissection planes and vessels and avoid bleeding and perforation, and new scopes with bending capabilities, and different operating channel sizes, caliber, depth of field, and image definition.

Historically, different schools of ESD emerged in Japan, with each expert having a dedicated knife associated with a specific plan and technique of dissection, and specific electrosurgical settings. Most of these were associated with excellent outcomes. The present study by Ramai et al. might spark a discussion about the future evolution of those schools of different ESD techniques: will they merge into a single universal technique, or will they keep their specificities? When discussing this point with Japanese experts, it seems that the specificity of each ESD school is preserved in Japan, despite the continuous evolution of ESD techniques. What is, or will be, the situation in the West in the hands of the second or third generation of endoscopists trained in ESD? Perhaps a more pragmatic approach will be taken that mixes schools and techniques for maximizing ESD safety, cure rates, and speed.

In conclusion, this study provides evidence for using Tr-ESD or Tu-ESD as much as possible, but does not integrate novel techniques, including the added value of saline immersion ESD [8], which could, in the near future and in association with technical advances, rechallenge these data to the benefit of patient safety, procedure times, and curative outcome.

Publication History

Article published online:
20 August 2025

• References

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• 2 Ramai D, Qatomah A, Chun M. et al. Performance of three major techniques for endoscopic submucosal dissection: a systematic review and network meta-analysis. Endoscopy 2025; 57
• 3 Libanio D, Pimentel-Nunes P, Bastiaansen B. et al. Endoscopic submucosal dissection techniques and technology: European Society of Gastrointestinal Endoscopy (ESGE) Technical Review. Endoscopy 2023; 55: 361-389
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