A catheter assembly (2) comprising a catheter hub (4), a hollow tubular catheter (10), a needle (30), a valve assembly (70), a valve opener (50), and a needle guard assembly (120). The needle guard assembly comprises a housing (122) having the needle extending therethrough and having a distal end (126) and a proximal end (124), the housing being connected at its distal end to the proximal end of the catheter hub, a needle guard (140) disposed within the housing, the needle guard comprising a needle trap (142) moveable between a ready position, in which the needle trap is held to one side of the shaft of the needle extending through the housing, and a protected position, in which the needle trap blocks the sharpened needle tip (36) of the needle within the housing, the needle trap comprising a first end and a second end, a resilient arm (150) biasing the needle trap into the protected position, the resilient arm bearing against the inner wall of the housing to urge the needle trap into the protected position, wherein the needle trap and the resilient arm are folded together to one side of the needle shaft in the ready position, a coupling arm (160), in the ready position the coupling arm coupling the housing to the proximal end of the catheter hub, movement of the needle trap from the ready position to the protected position causing the coupling arm to release the housing from the catheter hub, wherein the coupling arm is connected to the second end of the needle trap along a line extending perpendicular to the shaft of the needle.L'invention concerne un ensemble cathéter (2) comprenant un raccord de cathéter (4) ； un cathéter tubulaire creux (10), le cathéter étant relié, au niveau de son extrémité proximale, à l'extrémité distale du raccord de cathéter ； une aiguille (30) ayant une pointe d'aiguille (36) ； un tube d'extension creux (62), le tube d'extension étant relié, au niveau de son extrémité distale, au raccord de cathéter entre ses extrémités proximale et dis
