Direct dilation-free stent delivery using a novel 0.035-inch guidewire in endoscopic ultrasound-guided biliary drainage: the new ‘Flush surface’ method

Stent delivery following guidewire placement is the most technically demanding step of endoscopic ultrasound-guided biliary drainage (EUS-BD [ 1 ] [ 2 ] [ 3 ]). Although various devices can dilate endosonography-created routes, excessive tract dilation increases the risk of bile leakage [ 4 ] [ 5 ], making stable stent delivery without additional tract dilation desirable. Conventional 0.035-inch guidewires generally exceed 0.75 mm in outer diameter, limiting compatibility with 19-gauge needles (inner diameter ~0.7 mm); this novel 0.035-inch guidewire has a reduced outer diameter (0.65 mm), enabling insertion through a 19-gauge needle while preserving high shaft stiffness ([ Fig. 1 ] a ). Compared with 0.025-inch guidewires ([ Fig. 1 ] b ), the larger outer diameter minimizes step-off between the guidewire and the stent delivery system, potentially improving coaxial alignment and pushability during stent advancement ([ Fig. 1 ] c ). Here, we describe the “flush surface method,” compatible with a 19-gauge needle which enables smooth stent delivery without additional tract dilation ([ Fig. 1 ] d, e ; [ Video 1 ]). Fig. 1 Comparison of outer diameters of different guidewires and the step-off configuration. a Comparison of the novel 0.035-inch guidewire (0.65 mm) and the conventional 0.035-inch guidewire (approximately 0.8 mm), demonstrating compatibility with a 19-gauge needle (inner diameter of approximately 0.7 mm). b, c Images comparing a conventional 0.025-inch guidewire (left) and the novel 0.035-inch guidewire (right), highlighting the reduced step-off between the novel guidewire and the inner sheath of the stent delivery system. d, e Schematic illustrations comparing the conventional 0.025-inch guidewire (left) and novel 0.035-inch guidewire (right), demonstrating how the minimized step-off with the novel guidewire facilitates direct stent delivery without any additional tract dilation. Download Video The flush surface method in EUS-guided biliary drainage. EUS, endoscopic ultrasound.Video 1 A 60-year-old woman with obstructive jaundice caused by pancreatic cancer was referred for EUS-guided hepaticogastrostomy (EUS-HGS). A 19-gauge needle (EZ Shot 3 Plus; Olympus, Tokyo, Japan) punctured the B2 intrahepatic bile duct. After contrast injection ([ Fig. 2 ] a ), the novel 0.035-inch guidewire (CAPELLA 0.035; Japan Lifeline, Tokyo, Japan) was directly inserted through the needle, advancing into the common bile duct ([ Fig. 2 ] b ). Because of its stiff shaft and reduced step-off, the self-expandable metal stent delivery system advanced smoothly without a dedicated tract dilation device ([ Fig. 2 ] c ). Stent deployment was successful ([ Fig. 2 ] d ), with no adverse events. Fig. 2 EUS-guided hepaticogastrostomy using the novel guidewire in the first patient. a Contrast injection following 19-gauge puncture of the intrahepatic bile duct. b Direct insertion of the novel 0.035-inch guidewire through the 19-gauge needle. c Fluoroscopic image showing smooth delivery of a self-expandable metal stent without tract dilation. d CT scan confirming appropriate stent placement. This technique was subsequently applied in another patient undergoing EUS-HGS, enabling successful placement without adverse events ([ Fig. 3 ] a–d ) and without additional tract dilation. Fig. 3 EUS-guided hepaticogastrostomy using the novel guidewire in the second patient. a Contrast injection after 19-gauge puncture. b Direct insertion of the novel guidewire. c A fluoroscopic image showing successful plastic stent placement without any tract dilation. d CT scan confirming appropriate plastic stent placement. EUS, endoscopic ultrasound. Overall, the flush surface method enables direct stent deployment without tract dilation using a 0.035-inch guidewire in selected EUS-BD cases. These findings suggest that the guidewire’s outer diameter plays a critical role in facilitating dilation-free stent delivery. Reproducibility and clinical impact should be further investigated. Endoscopy_UCTN_Code_TTT_1AS_2AH Publication History Article published online: 15 June 2026 © 2026. 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/). Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany