A catheter assembly for use in accessing a vasculature of a patient during renal replacement or other therapies is disclosed. In one embodiment, the catheter assembly includes a catheter body that defines first and second lumens. The catheter body defines a distal tip region that includes a venous lateral opening that is in fluid communication with the first lumen and includes a distal-facing portion. The distal tip region further includes an arterial lateral opening that is in fluid communication with the second lumen, includes a distal-facing portion, and is substantially un-staggered with respect to the venous lateral opening. A distal end opening is defined on the distal tip region and is sized to pass a fluid therethrough. In one embodiment, the distal end opening is in fluid communication with a third lumen of the catheter body that can withstand high fluid flow rates associated with power injection of contrast media.