A filter assembly for use with a surgical suction tool for removing fluid and debris from a surgical site includes a conical filter element with a plurality of orifice arrays spaced along the length of the conical body with successively decreasing orifice diameters. The filter element includes an annular flange at the mouth of the filter element that is clamped between a container and a cap. The container includes conically tapered wall to define a radial space between the container and the filter element to permit fluid flow around the filter element and through the container to an outlet tube fitting. A cap covers the mouth of the container with a threaded interface defined between the cap and the container. The threaded interface includes a dual pitch triple lead thread with a coarse lead-in pitch and a fine trailing pitch.
