Tissue sampling at ERCP in suspected malignant biliary strictures (Part 2)

Part I of this review in the previous issue of Gastrointestinal Endoscopy outlined the key points of tissue sampling at ERCP and considered intraductal bile aspiration cytology, cytologic/histologic analysis of retrieved plastic biliary stents and fine needle aspiration cytology. Specimen adequacy, slide preparation, and accuracy of slide interpretation, which is often influenced by the interpretation “philosophy” of individual cytopathologists, are fundamental to the effort to optimize cancer detection by using tissue sampling techniques at ERCP. Intraductal bile aspiration is simple and inexpensive but adds little to the other methods, which have higher rates of cancer detection. Therefore, bile aspiration is recommended only when other sampling techniques cannot be used. Cytologic evaluation of material from retrieved plastic biliary stents is relatively insensitive (32%) and impractical as a firstline approach to the diagnosis of malignant biliary obstruction because diagnosis is delayed until the stent is removed. However, it can be considered in patients undergoing stent exchange when other methods of tissue sampling fail to confirm the suspected diagnosis of malignancy. Endoscopic fineneedle aspiration (FNA) cytology has a lower rate of cancer detection (33%) than initially reported and is technically difficult. It is usually used to supplement other simpler methods. Part II of this review considers the remaining tissue sampling methods for use at ERCP: brush cytology, endobiliary forceps biopsy, and the multimodal tissue sampling. Methods for improving diagnostic yield are discussed. BRUSH CYTOLOGY