Abstract: Apparatus and a method of its use is disclosed for transfer of blood/body fluid from a fluids obtaining device which is placed in communication with a patient's body cavity containing the fluid desired to be obtained for analysis and depositing it in a collection container for storage and/or transport. The fluids obtaining device has a fluids retention component adapted to be alternatively coupled with either a sharp ended needle for penetrating a patient's body or a blunt ended cannula. A fluids displacing mechanism is positioned in the retention component and is reciprocated to either draw fluid from the patient into the retention component or to expel fluid therefrom. After drawing fluid from the patient, the needle is removed and replaced with the cannula. A closure member secured to an open end of the container includes a plug formed from an elastomeric material exhibiting the characteristics of being penetrable by the cannula and self resealable after withdrawal of the cannula.