A novel 6 Fr inside biliary stent system for perihilar biliary drainage

Endoscopic biliary drainage (BD) is commonly performed in patients with perihilar biliary obstruction; however, the most appropriate method remains controversial. The plastic stent technique involves placing the tip of inside stent within the bile duct. Recently, the clinical outcomes of the inside and conventional plastic stents or the metal stent for the management of BD have been reported to be comparable in patients with preoperable/unresectable cholangiocarcinoma 1 2 3. However, severe biliary strictures may not allow multiple inside stent placements, and another a replacement is occasionally difficult to advance through the biliary stricture, and involves a risk of migration. To overcome this limitation, we developed a 6 Fr inside biliary plastic stent (Fig. 1 a–d). Multiple 6 Fr stents can be deployed simultaneously in a side-by-side fashion over the guidewire. Herein, we present patients treated successfully for perihilar BD using this new system. Case 1: An 89-year-old man with malignant perihilar cholangiocarcinoma was admitted with acute cholangitis caused by dysfunction of a previously placed 7 Fr inside biliary stent in the left hepatic duct. After extracting the occluded biliary stent, endoscopic retrograde cholangiography (ERC) confirmed bismuth type IV perihilar biliary obstruction. The 0. 025-inch guidewires were placed in the bilateral hepatic ducts. We successfully deployed 6 Fr inside biliary stents in the bile duct along the guidewire without complications (Fig. 2 a–f, Video 1). Case 2: A 78-year-old woman with IgG4-sclerosing cholangitis was admitted to our hospital. ERC confirmed perihilar biliary obstruction. We placed 6-Fr inside biliary stents simultaneously in the bile duct (Fig. 3, Video 1). In conclusion, this novel 6 Fr inside biliary stent system is useful for treating perihilar biliary obstruction. We believe that this system is a new drainage option and the least invasive approach available for the management of BD in patients with benign and malignant perihilar biliary obstructions. EndoscopyUCTNCodeTTT₁AR₂AZ Article published online: 30 January 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