A method for collecting and filtering biological material from blood and other fluids during a surgical procedure includes: attaching a first cover including a suction port and an intake port to a collection trap; attaching a suction source to the suction port; attaching an instrument to the intake port, through which blood and tissue are suctioned and received into the collection trap; filing the collection trap with blood and tissue; removing the collection trap from the first cover; attaching a second cover to the collection trap in place of the first cover, the second cover including a suction port and a plunger, the plunger including a press head having a screen portion permitting blood and other fluids to pass; attaching a suction source to the suction port of the second cover; separating the blood from the tissue by deploying the plunger; and drawing off the blood through the suction port.