A blood collection cartridge has a distal end, a proximal end, and defines a container interior. The cartridge includes a resealable closure sealing the distal end of the container, having a closure distal end and a closure proximal end. The cartridge also includes a cap sealing the proximal end of the container, having a cap distal end and a cap proximal end. The cartridge further includes a stopper disposed within the container interior sized relative to the container to provide sealing engagement with the sidewall of the container, the stopper having a stopper distal end and a stopper proximal end. A first fluid reservoir 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.
