Filter for Fine Needle Biopsy

Abstract

A biopsy needle comprises a first lumen open to a tissue penetrating distal tip of the needle for receiving a tissue sample therein and a second lumen in combination with a filter separating the first and second lumens from one another, the filter being configured to permit fluids to pass therethrough while preventing the sampled tissue from passing therethrough.

1 .- 19 . (canceled) 
     
     
         20 . A method for performing a needle biopsy, comprising:
 advancing a biopsy needle into a target portion of tissue to capture a sample of the target tissue within an opening at a distal end of a longitudinal body of the biopsy needle, the opening being open to a first lumen extending through the longitudinal body, the longitudinal body further including a first portion slidably received within a second lumen of an outer tube and a second portion extending distally from the first portion to a tissue penetrating distal tip, an outer diameter of the longitudinal body being selected to form an annular space between an inner surface of the second lumen and an outer surface of the longitudinal body, the biopsy needle further including a stylet slidably received within the second lumen;   opening the second lumen to receive tissue therein by moving the stylet from an insertion position in which a distal end of the stylet seals the distal opening to a sampling position in which the stylet is moved proximally relative to the longitudinal body; and   reducing a pressure within the first lumen to pass fluids through a filter formed on the second portion of the longitudinal body, the filter permitting fluid communication between the second lumen and the annular space while preventing the sampled tissue from passing therethrough.   
     
     
         21 . The method according to  claim 20 , further comprising:
 moving the stylet to a filtering position in which the stylet is positioned proximally of the second portion of the longitudinal body so that fluid may flow from the distal end of the first lumen through the filter to the annular space.   
     
     
         22 . The method according to  claim 20 , further comprising:
 ejecting sample tissue from the first lumen by moving the stylet distally to the insertion position.   
     
     
         23 . The method according to  claim 20 , further comprising:
 forming a seal about the longitudinal body with a distal end of the second lumen of the outer tube.   
     
     
         24 . The method according to  claim 23 , wherein a proximal end of the outer tube includes a proximal port coupleable to a source of negative pressure to aspirate fluids therefrom, the seal facilitating a withdrawal of the fluids from the second lumen into the annular space via an application of suction to the first lumen. 
     
     
         25 . The method according to  claim 20 , wherein the filter includes a plurality of openings formed through a wall of the longitudinal body. 
     
     
         26 . The method according to  claim 24 , wherein the openings are between 1 μm and 250 μm in diameter. 
     
     
         27 . The method according to  claim 24 , wherein the openings are distributed around the circumference of the second portion and are sized to permit blood cells to pass therethrough. 
     
     
         28 . The method according to  claim 24 , wherein the openings are less than approximately 10 μm in diameter. 
     
     
         29 . The method according to  claim 24 , wherein the openings are greater than approximately 8 μm in diameter. 
     
     
         30 . The method according to  claim 24 , wherein the openings are distributed over the second portion in a substantially helical pattern. 
     
     
         31 . The method according to  claim 23 , wherein the source of negative pressure is a syringe. 
     
     
         32 . The method according to  claim 20 , wherein a cross-sectional shape of the outer tube and the longitudinal body is symmetrical. 
     
     
         33 . The method according to  claim 32 , wherein the cross-sectional shape is circular.