Abstract: A shielded cannula for use with an I.V site having a threaded exterior surface and a septum comprises a cannula assembly including a hub having an open proximal end, a distal end, and a cavity therein, and a cannula having a proximal end projecting from the distal end of the hub, a distal end and a lumen therethrough in fluid communication with the cavity. A shield is connected to the cannula assembly and surrounds at least the proximal end of the cannula. The shield has a cylindrically shaped inside surface with at least one helical thread formed in the inside surface. A pointed plastic projection extends outwardly from the thread. The projection includes a base portion and a tip portion wherein the tip portion is positioned to be far enough away from the thread so that the tip portion is deflected by a thread on the exterior surface of the I.V. site when the thread of the shield engages the thread on the I.V. site.