Water pressure method for endoscopic submucosal dissection of a rectal tumor on the gravitational side close to the dentate line

Adequate submucosal exposure and visibility are vital for effective and safe endoscopic submucosal dissection (ESD) [1]. For lesions located on the gravitational side, the mucosal flap tends to collapse as the dissection proceeds which hinders subsequent operation [2]. Position change for gravity assistance is usually preferred in this circumstance, but not always applicable [3]. In this case, we present use of the water pressure method (WPM) to facilitate ESD of a rectal tumor on the gravitational side close to the dentate line ([Video 1]).

Water pressure method for endoscopic submucosal dissection of a rectal tumor on the gravitational side close to the dentate line.Video 1

Case report

A 62-year-old man was referred with synchronous early esophageal cancer ([Fig. 1] a, [Fig. 1] b) and a rectal tumor ([Fig. 2] a, [Fig. 2] b). A strategy of ESD for two lesions at one session was selected. Under general anesthesia with intratracheal intubation, esophageal ESD was completed ([Fig. 1] c, [Fig. 1] d), followed by rectal ESD. A shallow incision in the mucosa was begun on the anal side. Because the tumor was close to the dentate line, a narrow anal lumen limited endoscopic maneuverability. Furthermore, the mucosal flap collapsed due to gravity ([Fig. 2] c), making dissection difficult within the narrow submucosal space. Given the inconvenience of position change, WPM was adopted. The floating force exerted a natural countertraction against gravity, while active water pressure was appropriately applied as a complement ([Fig. 2] d, [Fig. 2] e, [Fig. 2] f). En bloc resection was achieved without major bleeding or perforation ([Fig. 2] g, [Fig. 2] h, [Fig. 2] i). Postoperative antibiotics were administered and no adverse events occurred other than transitory fever. Histopathology identified the rectal tumor as a tubular adenoma with high-grade dysplasia and R0 resection ([Fig. 3]).

Fig. 1 a White-light imaging of the esophageal lesion. b Blue laser imaging of the esophageal lesion. c Endoscopic submucosal dissection was performed smoothly. d The resected esophageal specimen, which pathology confirmed was moderate-differentiated esophageal squamous cell carcinoma invading the lamina propria mucosa with R0 resection.

Fig. 2 a Forward and b retroflexed view of colonoscopy revealed a 25-mm protruding lesion (Paris type 0- Is) in the left wall of the rectum extending close to the dentate line. c The collapsed mucosal flap after a C-shape mucosa incision. d After applying the water pressure method, buoyancy under water immersion provided a countertraction that better exposed the submucosa. The underwater magnified effect also improved visualization during dissection. e The lateral mucosal flap was effectively lifted via active water pressure. f Buoyancy was continuous during the whole procedure. g Forward view showing a minor inner circular muscle injury. h Retroflexed view of the ulcer after resection. i Resected rectal specimen.

Fig. 3 Histopathology revealed a tubular adenoma with focal high-grade dysplasia with clear vertical and horizontal margins. A stratified squamous epithelium of the anal canal was noted (red arrow), close to the distal margin of the lesion (yellow arrow).

Conclusions

Although various traction techniques have been proposed [4] [5], WPM requires no special devices and is easy to use; therefore, it may be an alternative option to facilitate difficult ESD, especially for lesions on the gravitational side in patients for whom position change is difficult ([Fig. 4]). Furthermore, WPM could be combined with adjunctive traction devices as needed.

Fig. 4 Schematic illustration of the water pressure method to facilitate endoscopic submucosal dissection of a lesion located on the gravitational side. a Under conventional gas insufflation, the mucosal flap collapses due to the gravity, leaving insufficient submucosal operation space. b With the water pressure method, buoyancy makes the mucosal flap float up against gravity, while active water pressure via water-jet of endoscope is utilized as a complement to lift the mucosal flap that expands submucosal space.

Conflict of Interest

The authors declare that they have no conflict of interest.

• References

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Publication History

Received: 02 January 2024

Accepted after revision: 16 February 2024

Article published online:
15 April 2024