Abstract: The present invention involves a elongated member, such as a wire guide, that is used with in a endoscopic procedure. In one aspect of the invention, the elongate member includes a first system of indicia comprising a scale reference markings that can include numeric indicia, sequentially increasing markers, etc., located at regular increments (e.g., 1 cm) on the distal portion of the elongate member, that permit measurement of structures within a body passage. In one example, an exchange wire guide having a radiopaque marker on the distal portion is positioned under fluoroscopy at a first location, such as the distal point of a stricture, and the scale reference marking on the wire guide that visible in the viewing region of the endoscope is read. The wire guide is partially withdrawn such that the marker corresponds to a second position (e.g., the proximal point of the stricture) and the new scale reference marking is read. The difference is calculated to determine the length of the structure.