Gel immersion in endoscopy: Exploring potential applications

Table 4 Reports on gel immersion endoscopy for colon and rectum

Ref.	Year	Article type	Gel/jelly type	Pathophysiology	Indication for gel immersion/study settings	Delivery procedure	Outcome	Obstacles for gel immersion
Yano et al[61]	2021	Case report	OS-1 jelly	Duodenal ulcer	Bleeding from ileocecal valve	Forceps channel with auxiliary injection cap	Successfully identified the bleeding point with double-balloon endoscopy	-
Teshima et al[62]	2022	Case report	OPF-203	Diverticular hemorrhage	Colonoscopy using gas insufflation and water immersion was difficult to secure the visual field	Forceps channel with auxiliary injection cap	Using gel ensured a clear visual field and allowed for the estimation of the bleeding point	A total of 600 mL of the gel was used
Suto et al[63]	2022	Case report	OPF-203	Diverticular hemorrhage	Despite flushing with water, the bleeding diverticulum could not be identified	-	The vessel within the smaller diverticulum was identified, and the site was successfully clipped	-
Abiko et al[64]	2023	Case report	OPF-203	Diverticular hemorrhage	Detecting of bleeding diverticulum could not be identified due to the large volume of clotted blood and severe active bleeding	Injected through long-hood	Gel retained within the long hood facilitated the detection of colonic diverticulum and enabled to identify the bleeding point, leading to successful hemostasis	-
Kobayashi et al[65]	2022	Case series	OPF-203	Case 1; diverticular hemorrhage; case 2 hemorrhoid	Bleeding point could not be identified with large amount of blood flow in two cases	-	Injection of the gel helped to identify the bleeding point in the diverticulum and successfully carried out endoscopic band ligation	-
Takada et al[66]	2022	Case report	OPF-203	Sessile serrated lesion	Under water EMR could not be performed due to the rapid mixing of bowel fluid from the terminal ileum compromised visibility	-	A clear view of the lesion margin was maintained and en-bloc resection was achieved	-
Kuwabara et al[67]	2022	Case report	OPF-203	EMR; protruded lesion extending into the diverticulum	Difficult to ensure sufficient buoyancy of the lesion	-	Under securing the sufficient buoyancy, the EMR had been succeeded	-
Jinushi et al[45]	2022	Case report	OPF-203	EMR; sigmoid colon polyp	Difficult to identify a bleeding point after underwater EMR	Secondary water delivery tube	Hemostasis with clips was achieved after securing a good visual field	-
Yoshimoto et al[70]	2022	Case report	OPF-203	EMR; Ileocecal valve polyp	To enhance the visibility of tumor located in the proximal lip of the ileocecal valve	-	Under-gel EMR was performed with a hexagonal snare; en-bloc resection was achieved without residual section	-
Yamamoto et al[71]	2023	Case report	OPF-203	Retrospective case series	Comparison between 6 cases of under-gel EMR with partial submucosal injection (PI) and 8 cases of under-gel precutting EMR among 348 patients with colorectal polyps	Forceps channel with auxiliary injection cap	En-bloc resection rate was 100% with under-gel EMR with PI, and 50% with under-gel precutting EMR	While it is a small, single-center retrospective case series, long-term outcomes were not assessed, and the quality of comparisons is low due to reliance on historical control data
Yamamoto et al[72]	2022	Case report	OPF-203	EMR; lateral spreading tumor-nongranular pseudo depressed type	Rapid mixing of fresh blood with water compromised visibility	-	Successfully achieved complete resection using underwater EMR, partial injection method and OPF-203	-
Tashima et al[73]	2023	Case report	OPF-203	EMR; flat elevated tumor within the diverticulum near the ileocecal valve	Perforation risk due to the tumor location of inside diverticulum	-	Gel immersion endoscopy secured a clear lesion margin view	-
Maruyama et al[74]	2021	Case report	OPF-203	ESD; nongranular-type laterally spreading tumor at the descending colon	The points of bleeding were not visible because of rapid blood collection	-	Successfully achieved multiple hemostasis with forceps	-
Tashima et al[75]	2022	Case report	OPF-203	ESD; anorectal tumor with hemorrhoids close to the dentate line	Hemorrhoids were scattered on the anal side of the tumor	-	The tumor’s buoyancy provided a good dissection field. Additional gel injection enabled immediate hemostasis	-
Nakano et al[76]	2023	Case report	OPF-203	ESD; laterally spreading tumor, granular-nodular mixed-type tumor	To improve endoscopic visual field and submucosal approach due to the buoyancy of the lesion	-	Easily approach to the submucosal layer and smooth creation of the tunnel owing to the buoyancy of the gel. Bleeding in the tunnel was clearly visible in the gel	-
Yamada et al[77]	2022	Case report	OPF-203	Postoperative anastomotic stricture	Due to the multifocal hemorrhage caused by the incision performed prior to balloon dilation	-	The incision was successfully continued, and the bleeding points were clearly identified	-
Yamamoto et al[78]	2022	Case report	OPF-203	Pediatric sigmoid volvulus	The poor endoscopic view caused by contaminated bowel fluid	-	Gel provided a clear endoscopic view and helped assess intestinal ischemia. The weight and pressure of the gel opened the twisted colon and facilitated volvulus passage in the left lateral decubitus position	-
Osera et al[79]	2023	Case report	OPF-203	EUS-guided puncture for rectal anastomotic obstruction	To identify puncture line under the EUS observation	-	Successfully punctured an obstruction site with 19G needle and made a dilation	-
Nomura et al[80]	2023	Case report	OPF-203	Colorectal stent insertion for colonic cancer	Poor endoscopic view due to severity of the stricture	-	Securing the visual field with gel and tapered tip of transparent hood	-

ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; EUS: Endoscopic ultrasound.