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DOI: 10.1055/a-2721-8976
Underwater peroral endoscopic myotomy improves visualization and reduces adverse events in a high-risk patient with type III achalasia
Authors
Underwater peroral endoscopic myotomy (uPOEM), a variation of peroral endoscopic myotomy (POEM), eliminates gas insufflation, reducing complications such as pneumomediastinum and capnothorax, particularly in high-risk patients with comorbidities like chronic obstructive pulmonary disease (COPD [1] [2]). The underwater approach improves visualization of tissue planes, enhances the dissection process, and facilitates vessel cauterization, minimizing adverse effects [3] [4].
An 84-year-old man with type III achalasia (Eckardt score: 9) and severe COPD and other comorbidities presented with severe dysphagia with regurgitation and malnutrition was referred for POEM. Given his high risk for insufflation-related complications, uPOEM was performed under general anesthesia with the patient in the supine position. Using a single-channel Olympus gastroscope equipped with a distal cap and a 4 mm T-type gold-knife (Micro-Tech, Nanjing, China), a mucosal incision (endocut-I) was made on the posterior esophageal wall at 23 cm. Submucosal tunneling (endocut-Q or precise SECT) was then carried out under continuous saline immersion, extending to 43 cm, thus entering the gastric side ([Fig. 1]). Subsequently, a selective myotomy (endocut-Q) of the circular muscle fibers was performed from 24 to 42 cm, also using the underwater technique. The saline immersion significantly enhanced visualization due to water-induced magnification, allowing for clearer differentiation of submucosal and muscular layers and improving vessel identification and cauterization ([Fig. 2]; [Video 1]). However, a mild reduction in cutting efficiency, attributed to the saline environment, necessitated adjustments to electrosurgical settings. No adverse events occurred during or after the procedure. Barium swallow performed 14 days after the procedure confirmed the complete passage of barium.




Studies have demonstrated the feasibility and safety of uPOEM, with high clinical success rates and minimal complications [3]. This approach is particularly beneficial to patients with insufflation-related risk factors, as it reduces adverse events and improves procedural outcomes [2] [4]. Standardized protocols further optimize its efficacy, highlighting its role as a valuable alternative to conventional POEM in selected cases [1] [5].
uPOEM effectively combines safety and procedural precision, making it an ideal technique for managing achalasia in high-risk patients while minimizing complications and enhancing surgical outcomes.
Endoscopy_UCTN_Code_TTT_1AO_2AP
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Publication History
Article published online:
29 October 2025
© 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).
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References
- 1 Nguyen NQ, Binmoeller KF, Nett A. et al. Outcomes of EUS-directed underwater peroral endoscopic myotomy (UPOEM) for achalasia using a standardized protocol. Gastrointest Endosc 2020; 91: AB146
- 2 Uchima H, Colan J, Marín I. et al. Underwater peroral endoscopic myotomy after tension capnoperitoneum and capnothorax during POEM. Endoscopy 2019; 51: E135-E136
- 3 Binmoeller KF, Bhat YM. Underwater peroral endoscopic myotomy. Gastrointest Endosc 2016; 83: 454-455
- 4 Hallit R, Barret M, Abouali E. et al. Underwater peroral endoscopic myotomy. Endoscopy 2018; 50: E298-E299
- 5 Ramakrishnan P, Azeem N. Underwater cricopharyngeal peroral endoscopic myotomy. Endoscopy 2020; 52: E391-E392
