Spring-ejected biopsy marker

Abstract

A device for inserting a marker into tissue at a biopsy site including an elongate shaft that moves conjointly with a plunger, and a spring secured to the distal end of the shaft. The device may comprise a cannula configured to receive a distal end of the shaft, and with a crimp, dimples, or other features formed near the shaft's distal end. The cannula may comprise a lateral aperture where a marker may be ejected from the lumen thereof. A ramp portion may be formed in communication with the lateral aperture, and the ramp portion may comprise a preselected slope that controls the angle at which the marker is ejected.

1 - 20 . (canceled) 
     
     
         21 . A marker delivery device comprising:
 a delivery cannula having a distal end including a lateral aperture;   a distal tip attached to the distal end of the delivery cannula, a proximal end of the distal tip having a ramp portion inclined toward the lateral aperture, at least one biopsy marker being receivable within the delivery cannula proximate to the lateral aperture;   a push rod having a first end disposed at least partially within the tube, wherein the push rod is movable in a direction toward the distal end of the tube to engage the received at least one biopsy marker; and   a marker stop located between the received at least one biopsy marker and the lateral aperture.   
     
     
         22 . The marker delivery device of  claim 21 , wherein the marker stop includes a plurality of bumps. 
     
     
         23 . The marker delivery device of  claim 22 , wherein the plurality of bumps are located on a side circumferentially away from the lateral aperture. 
     
     
         24 . The marker delivery device of  claim 23 , wherein the plurality of bumps includes two bumps respectively located at a same circumferential offset from the lateral aperture. 
     
     
         25 . The marker delivery device of  claim 24 , wherein the two bumps are respectively located approximately  135  degrees in each circumferential direction from the lateral aperture. 
     
     
         26 . The marker delivery device of  claim 22 , wherein the plurality of spaced apart bumps are approximately circumferentially equidistant from each other. 
     
     
         27 . The marker delivery device of  claim 21 , wherein the marker stop includes an at least partially circumferentially extending rib. 
     
     
         28 . The marker delivery device of  claim 21 , wherein the marker stop includes a flexible flap. 
     
     
         29 . The marker delivery device of  claim 21 , wherein the marker stop includes a resilient bulge. 
     
     
         30 . The marker delivery device of  claim 21 , further comprising:
 a resilient member extending from the first end of the push rod, wherein the resilient member is configured to engage the received at least one biopsy marker when the push rod travels in a direction toward the distal end so as to drive the at least one biopsy marker through the lateral aperture of the tube.   
     
     
         31 . The marker delivery device of  claim 30 , wherein the resilient member comprises a spring having at least a first pitch region of coils and a second pitch region of coils, wherein the coils of the first pitch region are more compactly spaced relative to the second pitch region. 
     
     
         32 . The marker delivery device of  claim 30 , wherein the resilient member is configured to laterally deflect within the delivery cannula so as to allow travel of the push rod beyond the marker stop without requiring any lateral deflection of the push rod within the delivery cannula.