A syringe-based device includes a housing, a pre-sample reservoir, and an actuator. The housing defines an inner volume between a substantially open proximal end portion and a distal end portion that includes a port couplable to a lumen-defining device. The pre-sample reservoir is fluidically couplable to the port to receive and isolate a first volume of bodily fluid. The actuator is at least partially disposed in the inner volume and has a proximal end portion that includes an engagement portion and a distal end portion that includes a sealing member. The engagement portion is configured to allow a user to selectively move the actuator between a first configuration such that bodily fluid can flow from the port to the pre-sample reservoir, and a second configuration such that bodily fluid can flow from the port to a sample reservoir defined at least in part by the sealing member and the housing.