A catheter that comprises a hub, an elongated conduit, and at least one lumen therein. The lumen includes a proximal lumen section, a distal lumen section, and an intermediate lumen section extending between the proximal and distal lumen sections. The cross-sectional dimension of the intermediate lumen section is less than the cross-sectional dimension of the distal lumen section. In one embodiment, the cross-sectional dimension of the intermediate lumen section is less than the cross-sectional dimension of the proximal lumen section. In certain embodiments, the lumen tapers from the distal and/or proximal lumen sections to the intermediate lumen section.