The present invention relates to a system comprising a flexible bag for storing the drained secretion with an anti-collapse device (9), being connected on one side to a "T" valve which is provided with protective lid and, on the other side, to the flow control backflow preventer valve consisting of a one-piece circular core (2) of elastomeric material which is secured to the housing, said core containing a central plug connected by radial rods to the borderline of the circular body thereof, so that said core is used in two-way housings, an inlet and an outlet, said valve composed of a one-way valve. Said system further comprising within the housing a clot fractioning device at the inlet and an anti-clogging device from the maximum opening point of the core (2).
