An apparatus, comprising: a cannula assembly (120, 220, 420, 620); a housing (101, 201, 401, 601) including a proximal end portion (202, 402, 602) and a distal end portion (203, 403, 603) and defining an inner volume (111, 211, 411, 611) therebetween, the housing (101, 201, 401, 601) having an inlet port (105, 205, 405, 605) configured to be removably coupled to the cannula assembly (120, 220, 420, 620); a fluid reservoir (130, 230, 430, 630) having an inner volume (133, 233, 433, 633) disposed in the inner volume (111, 211, 411, 611) of the housing (101, 201, 401, 601), the fluid reservoir (130, 230, 430, 630) configured to be in selective fluid communication with the inlet port (105, 205, 405, 605) to receive and isolate a first volume of bodily fluid to be withdrawn from the patient; a flow control mechanism (140, 240, 440, 640) at least partially disposed in the inner volume of the housing and configured to move relative to the housing between a first configuration and a second configuration, the flow control mechanism (140, 240, 440, 640) defining a fluid flow path between the cannula assembly (120, 220, 420, 620) and the fluid reservoir (130, 230, 430, 630) when in said first configuration; and an actuator (180, 480) operably coupled to the flow control mechanism (140, 240, 440, 640) and configured to move the flow control mechanism from said first configuration, in which the inlet port (105, 205, 405, 605) is placed in fluid communication with the fluid reservoir (130, 230, 430, 630), to said second configuration, in which the fluid reservoir is fluidically isolated from the cannula assembly (120, 220, 420, 620), characterized in that said inner volume (133, 233, 433, 633) of the fluid reservoir is configured to increase in response to the movement of the flow control mechanism between said first and second configurations to produce a negative pressure within the inner volume (133, 233, 433, 633) of the fluid reservoir prior to the flow control mechanism being placed in said second configuration, such that bodily fluid can flow from the cannula assembly, through the inlet port via the fluid flow path, and to the fluid reservoir. a cannula assembly (120, 220, 420, 620); a housing (101, 201, 401, 601) including a proximal end portion (202, 402, 602) and a distal end portion (203, 403, 603) and defining an inner volume (111, 211, 411, 611) therebetween, the housing (101, 201, 401, 601) having an inlet port (105, 205, 405, 605) configured to be removably coupled to the cannula assembly (120, 220, 420, 620); a fluid reservoir (130, 230, 430, 630) having an inner volume (133, 233, 433, 633) disposed in the inner volume (111, 211, 411, 611) of the housing (101, 201, 401, 601), the fluid reservoir (130, 230, 430, 630) configured to be in selective fluid communication with the inlet port (105, 205, 405, 605) to receive and isolate a first volume of bodily fluid to be withdrawn from the patient; a flow control mechanism (140, 240, 440, 640) at least partially disposed in the inner volume of the housing and configured to move relative to the housing between a first configuration and a second configuration, the flow control mechanism (140, 240, 440, 640) defining a fluid flow path between the cannula assembly (120, 220, 420, 620) and the fluid reservoir (130, 230, 430, 630) when in said first configuration; and an actuator (180, 480) operably coupled to the flow control mechanism (140, 240, 440, 640) and configured to move the flow control mechanism from said first configuration, in which the inlet port (105, 205, 405, 605) is placed in fluid communication with the fluid reservoir (130, 230, 430, 630), to said second configuration, in which the fluid reservoir is fluidically isolated from the cannula assembly (120, 220, 420, 620), characterized in that said inner volume (133, 233, 433, 633) of the fluid reservoir is configured to increase in response to the movement of the flow control mechanism between said first and second configurations to produce a negative pressure within the inner volume (133, 233, 433, 633) of the fluid reservoir prior to the flow control mechanism being placed in said second configuration, such that bodily fluid can flow from the cannula assembly, through the inlet port via the fluid flow path, and to the fluid reservoir.