The present invention discloses a catheter instrument 1000 comprising a needle tip shielding device 100, a catheter hub 200 and a needle unit 300, wherein the needle unit 300 is provided with connecting means 301 for connection to the catheter hub 200, and with connecting means 302 for connection to an external device. The needle tip shielding device 100 is comprising a body with a rear side 106, a front side 107, an outer surface 108 connecting the rear side 106 and the front side 107, a hole 102 extending from the rear side 106 to the front side 107, and a resilient arm 103 extending at an attachment point 105 from the front side 107 of the body; wherein the resilient arm 103 has a resting stale from which it may be forced to yield free passage through the hole 102 in an axial direction of the body, the resilient arm 103 being adapted for clamping a needle tip 304 of a hollow needle 303 extending through the hole 102 in a direction from the rear side 106 to the front side 107, when being in the resting state.