Device having a first chamber for receiving a body fluid

An apparatus for receiving a body fluid, wherein the apparatus comprises:

• a) a first chamber that can receive the body fluid, the first chamber having a cylindrical section, designed as a cylinder, and a displaceable wall, the first chamber further having an opening on a connecting part, which lies opposite the displaceable wall, the connecting part being designed to be connected to an external element,
• the displaceable wall having an opening, which can be selectively opened or closed by means of a barrier,
• wherein the displaceable wall is connected to a guide, the guide and the displaceable wall being arranged in the cylinder in such a way that the guide and the displaceable wall can be displaced together in the cylinder, wherein the guide is arranged on the side which is opposite the opening of the first chamber, and
• b) a second chamber which is mounted in or on the guide and that can receive the body fluid, the second chamber being closed by a sealing means, the second chamber having a constant effective size,
• wherein the size of the first chamber can be increased in order to draw the body fluid into the first chamber by moving the displaceable wall,
• wherein a movement of the second chamber within the guide is prevented by means of a blocking means, which can be removed, and after removing the blocking means, a movement of the second chamber relative to the guide and the displaceable wall can take place,
• the apparatus is designed to connect the first chamber and the second chamber to transfer body fluid from the first chamber to the second chamber via a longitudinally axial movement of the second chamber with respect to the displaceable wall in a first step, in which the sealing means of the second chamber is pierced by an opener, and in a next step, in which the second chamber moves together with the displaceable wall, the opening of the first chamber in the displaceable wall is opened.