- G.I.U.M.: immediately before using the G.I.U.M. catheter, the biliary stricture will be dilated using a 6-mm in diameter MaxForce balloon catheter (Microvasive Endoscopy, Boston Sc.). The G.I.U.M. catheter will be passed as a unit within its 8.5F sheath, alongside the guidewire. Once the basket/sheath is located above the stricture, the basket will be opened and passed through the strictured segment 1 time. The basket will then be pulled into the catheter, and the unit basket/catheter will be removed.. A X-ray will be taken with the meshes of the G.I.U.M. catheter opened inside the stricture, and the X-ray will be kept in a dedicated file. Specimens obtained with the G.I.U.M. will be smeared on glass slides and fixed in 95% ethanol immediately after collection, in the ERCP suite. Immediately after, the G.I.U.M. will be agitated in 10 ml of saline placed in a vial. Finally, all the material remaining between the wires of the G.I.U.M. will be rinsed through the sheath into a vial by perfusing 30 ml of CytoLytt solution (Cytyc) taken from the vial furnished by the manufacturer using a 20-ml sterile syringe into the same vial.