A distal end portion of an elongate shaft member of a catheter may be inserted into a liquid within a vessel. While the distal end portion of the elongate shaft member is inserted in the liquid in the vessel, a manipulable portion of the catheter may be manipulated within the liquid to remove an undesired fluid therefrom. The liquid may be pressurized to cause the liquid to flow into a lumen of the elongate shaft member from a distal end of the elongate shaft member at least toward a proximal end of the elongate shaft member to facilitate flushing of the undesired fluid from the lumen. The distal end portion of the elongate shaft member of the catheter may be inserted into the liquid within the vessel while at least the elongate shaft member is in a substantially horizontal orientation.