Gel immersion in endoscopy: Exploring potential applications

Table 3 Reports on gel immersion endoscopy for duodenal and small intestine lesions

Ref.	Year	Article type	Gel/jelly type	Pathophysiology	Indication for gel immersion/study settings	Delivery procedure	Outcome	Obstacles for gel immersion
Miyamoto et al[43]	2021	Case report	OPF-203	Duodenal ulcer	Bleeding ulcer; unable to detect bleeding point	Water jet instrument	Successfully observe the ulcer in detail by filling duodenal lumen with the gel after hemostasis	-
Hayashi et al[44]	2022	Case report	OPF-203	Diverticular bleeding	Bleeding; unable to detect bleeding diverticulum, poor maneuverability	-	Maneuverability and field of view improved. The bleeding point was identified and successfully clipped for hemostasis	-
Jinushi et al[45]	2022	Case series	OPF-203	Duodenal ulcer in anterior surface of the duodenal bulb	Saline solution was quickly mixed with blood, making it difficult to identify the bleeding site	Secondary water delivery tube	Successful identification of the bleeding point was achieved, and hemostasis was accomplished with hemostatic forceps	There was only one forceps channel, making it impossible to insert both the gel and the hemostatic forceps simultaneously. Therefore, secondary water injection tube was used
Miyakawa et al[46]	2021	Case series	OPF-203	Two cases of SNADETs	Technical difficulty of the EMR procedure	Forceps channel	The lesion floated in the gel-filled lumen, while the muscular layer remained flat, allowing the snare to be performed more safely	Compared to a similar technique (underwater EMR); it is less cost-effective
Tashima et al[47]	2021	Case report	OPF-203	SNADET	The endoscope contacted with the lesion and started bleeding, due to the strong intestinal peristalsis	-	By using both saline and gel, the duodenal lumen expanded, allowing for a clear view of the entire SNADET	-
Yachida et al[48]	2022	Case report	OPF-203	SNADET	Water jet alone could not fill the lumen with saline	Forceps channel with auxiliary injection cap	The lesion floated in the gel-filled lumen allowing en-bloc resection safely	-
Kasai et al[49]	2023	Case report	OPF-203	Ampullary tumor	Perform EMR on the ampullary tumor with double-balloon endoscopy	Forceps channel with auxiliary injection cap	Gel was injected gel without bubbles; the lumen sufficiently expanded, allowing the ampullary tumor to be clearly visible	-
Miyakawa et al[50]	2023	Retrospective comparison study	OPF-203	SNADETs	Comparing gel-based EMR (GIER; n = 22) and Underwater EMR (UEMR; n = 18) in procedure time and R0 resection rate	-	GIER had a significantly shorter procedure time and a higher R0 resection rate compared to UEMR	The small sample size may pose a problem for statistical power, and the amount of water used in the UEMR group was not recorded
Amino et al[51]	2021	Case series	OPF-203	SNADETs	Evaluating en-bloc resection rate and procedure time of using under-gel EMR for six consecutive cases of SNADETs	Forceps channel	Under-gel EMR showed 100% in en-bloc resection rate and median procedure time was 6 minutes without any adverse events	-
Yamashina et al[52]	2022	Retrospective comparison study	OPF-203	SNADETs	Comparing gel-based EMR (GIER; n = 10) and Underwater EMR (UEMR; n = 14) in R0 resection rate, en-bloc resection rate, median procedure time, median amount of filling water/gel and adverse events	Forceps channel with auxiliary injection cap	Median procedure was shorter in GIEMR group. Median amount of filling water/gel was lesser in GIEMR group. There are no difference in adverse events rates	The small number of data points may lead to statistical instability; some patient data (such as chief complaints) might be missing
Tashima et al[53]	2022	Case report	OPF-203	ESD; a tumor adjacent to the papilla	Unexpected massive bleeding occurred during submucosal dissection, obscuring the lesion and bleeding point	Forceps channel	Organ collapse was maintained with lower intraluminal pressure, ensuring stable endoscope maneuverability and a good approach to the lesion, allowing safe submucosal dissection	-
Goto et al[54]	2023	Case report	OPF-203	Brunner’s gland hyperplasia in the duodenal bulb	Due to the tumor's large size of 30 mm, which was expected to hinder snaring, gel-immersion EMR was performed	Forceps channel	Expansion of the lumen facilitated snaring and allowed for clear visualization of the snare's engagement	-
Okamoto et al[55]	2024	Case report	OPF-203	Supra-ampullary adenoma	Cold polypectomy for 10 mm diameter lesion in supra ampullary tumor	Forceps channel	The gel-immersed lesion was captured with an endoscopic snare; the gel remained in place throughout the procedure and only 200 g was required	-
Tashima et al[56]	2022	Case report	OPF-203	ESD; duodenal epithelial tumor	Due to the thin duodenal wall, there is a risk of perforation during ESD	Forceps channel with auxiliary injection cap	As ESD progressed, the buoyancy effect became more pronounced, ensuring working space to make dissection easier. Additionally, it was easy to identify bleeding points was also simplified	-
Kawaguchi et al[57]	2023	Case report	OPF-203	EMR; intestinal polyp for patient with Peutz-Jaghers syndrome	The polyp stalk could not be observed well with CO2 inflation	-	By injecting gel, the polyp stalk became visible, allowing for successful snaring; Further gel injection helped manage post-EMR bleeding	-
Matsubara et al[58]	2024	Case report	OPF-203	EMR; intestinal (ileum) polyp	The small intestine did not expand with water (attempting underwater EMR) alone, making it difficult to secure a working space	-	Inflating the double-balloon endoscopy's balloon prevented backflow of a gel, allowing the lumen to expand adequately and leading to successful EMR	-
Horitani et al[59]	2024	Case report	OPF-203	Small intestine bleeding	Flushing the lumen with water resulted in the immediate mixing of water and blood, making it impossible to identify the bleeding point	Forceps channel with auxiliary injection cap	Inflating the tip balloon of the double-balloon endoscope helped retain the gel in place, allowing for the identification and successful hemostasis of the intestinal hemangioma	-
Tomita et al[60]	2022	Case report	OPF-203	EUS for jejunal tumor observation	Injecting water into the duodenum and small intestine resulted in quickly flowing out, leaving little water	Forceps channel	The gel remained near the jejunum tumor, clearly separating the jejunal wall from the tumor and enabling its identification	-

ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; SNADET: Superficial non-ampullary duodenal epithelial tumor; GIEMR: Gel immersion endoscopic mucosal resection.