A blood collection cartridge (2) has a distal end (22), a proximal end (23), and defines a container interior (26). The cartridge includes a resealable closure (40) sealing the distal end of the container, having a closure distal end (41) and a closure proximal end (42). The cartridge also includes a cap (60) sealing the proximal end of the container, having a cap distal end and a cap proximal end. The cartridge further includes a stopper (32) disposed within the container interior sized relative to the container to provide sealing engagement with the side- wall (25) of the container, the stopper having a stopper distal end (34) and a stopper proximal end (35). A first fluid reservoir (28) is bounded by the sidewall between the closure proximal end and the stopper distal end, and a second fluid reservoir is bounded by the sidewall between the cap distal end and the stopper proximal end. An anticoagulant is disposed within the first fluid reservoir.
