Gel immersion in endoscopy: Exploring potential applications

Table 5 Reports on Gel immersion endoscopy for hepatobiliary and pancreas

Ref.	Year	Article type	Gel/jelly type	Pathophysiology	Indication for gel immersion/Study settings	Delivery procedure	Outcome	Obstacles for gel immersion
Toyonaga et al[81]	2022	Case report	OPF-203	Ampullary tumor	Evaluation whether the ampullary had duodenal muscularis propria or intraductal involvement. Securing visual field during papillectomy	Forceps channel with auxiliary injection cap	Successfully delineate the ampullary tumor without invasion of the duodenal muscularis propria or intraductal involvement. En-bloc endoscopic papillectomy was achieved	-
Toyonaga et al[83]	2023	Case series	OPF-203	Ampullary tumor	Evaluating the delineation and diagnosis of 12 consecutive patients study who were used gel immersion under the EUS observation	-	Delineation of the ampullary tumors were achieved in all patients. The diagnostic accuracies of biliary spread, pancreatic intraductal spread, invasion into duodenal muscularis propria, and pancreatic invasion were 83%, 100%, 83%, and 92%	-
Toyonaga et al[84]	2023	Retrospective study	OPF-203	Hepatobiliary observational EUS (evaluation of ampulla)	Fifty-nine consecutive patients who received EUS with gel	-	Duodenal distention was excellent, good, and poor in 58%, 34% and 7% of cases. The delineation rates of the papilla in the axial and longitudinal views were 98% and 66%	Retrospective, single-institution study; Radial and convex linear-arrayed echoendoscopes were used; Diagnostic ability of EUS with for periampullary lesions remains unknown
Sato et al[85]	2024	Case series	OPF-203	Hepatobiliary observational EUS (evaluation of ampulla)	Retrospective case series study: EUS images of the Vater were taken for 10 patients, with 10 images captured after injecting water into the duodenal lumen, followed by another 10 images after applying gel in the same manner.	-	The number of excellent observations (as defined by Toyonaga et al[81]) was 0.4 ± 0.80 with water immersion, while it was 3.8 ± 1.99 with gel immersion, showing a significant advantage of gel immersion in the visualization of the papilla	Confirmation bias exists; Case series retrospective study
Yokoyama et al[88]	2023	Case report	OPF-203	Balloon enteroscopy-assisted endoscopic retrograde cholangiography for biliary atresia with biliary stones	Debris and blood obscured the visual field	Forceps channel irrigator	Visualizing bleeding site. Hemostasis was achieved	-
Okuno et al[89]	2023	Case report	OPF-203	Pancreaticojejunostomy anastomotic stricture and pancreatic stones	-	-	Gel immersion endoscopy successfully securing the visual field during radial incision and cutting	-
Fukushi et al[90]	2023	Case report	OPF-203	Obstructive jaundice in post Roux-en-Y reconstruction patient	Difficult to identify afferent limb in Rounx-en-Y anastomosis	-	Mixture of the gel and contrast media successfully identified the afferent limb of the patient and reached the duodenal papilla	-
Ogura et al[91]	2023	Case report	OPF-203	WON	To avoid mis-deployment of a lumen apposing metal stent caused by large amount of debris or necrotic tissue	-	Injected the gel into the lumen of the WON; Obtained good visibility of the lumen of the WON	-
Ogura et al[92]	2023	Case report	OPF-203	EUS-guided transduodenal drainage	To avoid double mucosal puncture	-	Succeeded EUS-guided transduodenal drainage without double mucosal puncture	-

EUS: Endoscopic ultrasound; WON: Walled-off necrosis.