A needle assembly includes a needle, a rear needle cap and a front needle cap. The needle includes a needle hub and a needle shaft running through and attached to the needle hub. The shaft incorporates two sharp ends and an internal channel running through the entire length of the shaft. The needle hub includes a rear needle body and a front needle body. The rear needle cap is adapted to be attached to the rear needle body and the front needle cap is adapted to be attached to the front needle body. The front needle body incorporates a guiding channel and a locking receptacle connecting to and extending from the guiding channel in a needle detachment direction. The front needle cap includes an internal locking plug adapted to move along the guiding channel and be disposed inside the locking receptacle. The front needle cap also incorporates a funnel lip.