Abstract: A medical device for introducing fluid treating material to or removing a fluid material from a body cavity of a human or animal, including:a hollow, needle-like structure having a proximal end and a distal end, the proximal end having a beveled tip and being formed from a polymer which is sufficiently rigid at ambient temperature to permit puncture of skin by the beveled tip, and which becomes soft after a predetermined period of time exposed to body temperature and body fluids, thus preventing bodily trauma; anda hub attached to the distal end of the hollow needle-like structure and having a diameter greater than that of the hollow needle-like structure, the hub including a connector for attachment of a handle or a device for introducing fluid treating material to or removing fluid from the body cavity.