Needle assemblies and related methods in which a valve opener is used to push into a valve to open one or more slits on the valve to open the valve. The needle assemblies each includes a needle hub with a needle, a catheter tube with a catheter hub and the valve and valve opener positioned in the interior cavity of the catheter hub. The valve can have a valve skirt and a nose section of the valve opener can locate therein. One or more reliefs can be provided with the valve opener so that an elbow or diagonal section on a needle guard can project from a holding space within the valve opener through the relief.