A vascular access system which may be configured for blood draw may include a housing, which may include a distal end, a proximal end, and a slot disposed between the distal end and the proximal end. The slot may include a notch. The vascular access system may include a cannula hub, which may be disposed within the housing and movable with respect to the slot. The cannula hub may include a tab extending through the slot. The vascular access system may include a cannula extending distally from the cannula hub. In response to the tab being disposed within the notch, a distal tip of the cannula may be disposed within the housing. In response to advancing the tab along the slot to a distal end of the slot, the distal tip of the cannula is disposed distal to the distal end of the housing.