Abstract: A catheter assembly comprises a flexible tube having a liquid-receiving lumen therethrough. The tube has a proximal end for receiving liquid into the lumen and has a closed, but penetrable, distal end. The catheter assembly also comprises an adapter which includes a body operatively, but preferably removably, positioned on the distal end of the tube. A hollow cannula is mounted in and supported by an air purging element, so that the cannula extends through a passageway in the body and through the distal end of the tube in fluid communication with the lumen. The cannula provides a path to the outside environment for purging air from the lumen as liquid is introduced into the lumen. The distal end is sealable to retain liquid within the lumen after the air purging member is removed from the tube.