A Cholangioscopy-Based Novel Classification System for the Phenotypic Stratification of Dominant Bile Duct Strictures in Primary Sclerosing Cholangitis—the Edmonton Classification

BACKGROUND: Primary sclerosing cholangitis (PSC) is a chronic inflammatory condition causing bile duct strictures. Differentiating inflammatory strictures from malignant transformation is challenging. Cholangioscopy allows direct visualization with the option to biopsy. We describe our experience of cholangioscopy in PSC and propose a novel stricture classification system based on cholangioscopic findings. METHODS: All patients with PSC and a dominant stricture referred for cholangioscopy were reviewed. Based on visual characteristics with direct cholangioscopy, we propose a novel classification system for the extrahepatic form of PSC. RESULTS: The proposed Edmonton Classification system for extrahepatic PSC strictures consists of the following phenotypes: 1) ‘inflammatory type’, with mucosal erythema and active inflammatory exudate, 2) ‘fibro-stenotic type’, with concentric fibrotic scars, and 3) ‘nodular or mass-forming type’, with a mass in the involved segment of extrahepatic bile duct. From 2011–2017, 30 patients with PSC and a dominant stricture (21 M, mean age 46 years) underwent 32 cholangioscopy procedures. Cholangioscopy was technically successful in 29 of 32 procedures (91%). In these 29 stricture cases, inflammatory type was seen in 16 (55%), fibro-stenotic type in seven (24%) and nodular or mass-forming type in five (17%). In one (4%) procedure, there was no stricture or abnormality identified. CONCLUSION: Cholangioscopy is effective and safe for the evaluation of dominant biliary strictures in PSC. Based on our experience with cholangioscopy, we propose a novel classification system of extrahepatic PSC phenotypes: the Edmonton Classification.