A method of providing a plurality of filled product bags of sterile fluid includes positioning a bag assembly onto a filling machine. The bag assembly includes a tube, a filter assembly, bladders, and stems. A stem is attached to a bladder, forms a fluid passageway, fluidly connects to the tube, and provides fluid communication into the bladders. The method includes fluidly coupling an inlet of the filter assembly to a connection line in fluid communication with a fluid source, and filling the bag assembly with a fluid. Filling the bag assembly includes passing the fluid through the filter assembly, the fluid passageway, and into the bladder. The method includes sealing the fluid passageway at a location between the tube and the bladders. The method includes cutting the stem to form a partially filled product bag having the sealed passageway. The method includes performing an integrity test on the filter assembly.