Abstract: A cannula system for removing fluid from a patient's vasculature includes a cannula and an obturator. The cannula includes a proximal end, a distal end, and an elongate flexible tube extending therebetween. The cannula has a central lumen. The obturator is sized for insertion into the cannula's central lumen and is also configured to extend beyond the cannula distal end. A tapered portion at the cannula's distal end provides a smooth transition and an interference fit between the cannula and the obturator. The obturator includes an obturator central lumen and an opening at its distal end that is sized to receive a guidewire.