A needle assembly (100) for for percutaneously infusing fluids to a body and/or withdrawing fluids from a body is provided. The needle assembly (100) comprises a polymeric body (101) having a passageway (102) in a proximodistal direction. A wing assembly is secured to the body (101), and the wing assembly including first and second wings (103) extending laterally in opposite directions from said body (101). A hollow needle (104) is arranged in said passageway (102), such that it extends distally from said body (101). A shielding arm (105) is attached to the polymeric body (101), such that it is pivotable from an open position to a closed position, wherein a tip of the needle (104) is covered by the shielding arm (105) in the closed position while the needle tip is uncovered in the open position.