a biopsy marker deployment device adapted to selectively deposit a marker in a target location , such as a biopsy site . in one embodiment , the device includes a deployment assembly comprising a cannula adapted to house at least one marker , an outlet aperture defined by a portion of the cannula , and an actuatable pushrod slidably disposed and movable within the cannula . the deployment assembly further comprises a selectively opening outlet door movable between an open position and a closed position . the outlet door is biased in the closed position and at least partially obstructs the aperture in the closed position to prevent a marker from reentering the cannula upon deployment .