a fluid collection device having a primary container and a secondary container and a two stage fixation system for facilitating and controlling the fixation of cells in a sample of a biological fluid such as urine . the primary container generally comprises a plastic cup having a filtering apparatus disposed within it for filtering cells from the fluid . the primary container may contain a first stage fixative . the device further comprises a cover comprising a pressurizing chamber for forcing fluid through the filter and fixative delivery chamber for dispensing a fixative into the primary container . the filtered fluid may be reserved within a secondary container attached to the primary container . the filter having the cells retained on its surface is removable from the primary container for the purpose of laboratory analyses of the cells .