A catheter assembly is disclosed. This assembly may include a first elongate member having an internal lumen and a distal portion, a second elongate member, slidable within the first elongate member, and a spacer positioned between the second elongate member and the first elongate member. In this example, the spacer may be positioned at bendable portions of the first elongate member and the second elongate member such that the spacer maintains a substantially uniform spacing between the second elongate member and the first elongate member when the first elongate member and the second elongate member are in a curved orientation.