Vacuum assisted biopsy needle set

1. A needle set for a biopsy device, comprising:

an outer member having

a tip member having a working end, an opposite end and a tip lumen defined therebetween;

a cylinder portion having a first end hermetically connected to said opposite end of said tip member, a second end and a cylinder lumen defined therebetween, said cylinder lumen in fluid communication with said tip lumen;

a hub member defining a hub lumen in fluid communication with said cylinder lumen, said hub lumen in fluid communication with a pair of openings defined in opposite sides of said hub member;

said second end of said cylinder attached to said hub member at one of said opposite sides of said hub member and positioned so that said cylinder lumen is aligned with said hub lumen; and

a cylinder seal member positioned within said cylinder lumen and fixed to an interior surface of said cylinder, said cylinder seal member defining an opening therethrough in communication with said cylinder lumen, and a vent seal disposed within said hub lumen; and

an inner member having

a cannula slidably disposed within said cylinder lumen and through said opening of said cylinder seal member and having a proximal end and a distal end with an inner lumen defined therebetween, said cannula further defining a vent aperture adjacent said proximal end of said cannula;

a sampling portion attached to said distal end of said cannula, said sampling portion defining a sampling cavity;

a cannula seal member fixed to an outer surface of said cannula proximal to said sampling portion, said cannula seal member configured to movably seal within said cylinder lumen;

wherein the cannula includes an opening that is disposed between said cylinder seal member and said cannula seal member;

wherein at least said cannula seal member and said cylinder seal member cooperate to define a vacuum chamber; and

wherein said inner member and said outer member are movable relative to one another between

a retracted position in which said tip member covers said sampling cavity and said vacuum chamber is expanded, and

an extended position wherein said sampling portion is extended away from said tip member to expose said sampling cavity and said cannula seal member is moved away from said cylinder seal member to generate vacuum to bias tissue toward said sampling cavity,

wherein the generated vacuum selectively increases at the tissue site generally proportionally to the distance that said cannula seal member is moved away from said cylinder seal member; and

wherein said needle set is operable to be placed in a cocked position with said vent aperture exposed to vent air from the inner lumen as the cannula is moved to the extended position, said vent aperture being sealed by said vent seal when said cannula is in the extended position.

2. A needle set according to claim 1 , wherein said sampling cavity has an opening that is transverse to the axis of said cylinder lumen.

3. A needle set according to claim 2 , wherein said inner member further includes a piercing tip.

4. A needle set according to claim 1 , wherein said vent aperture is disposed opposite said sampling cavity relative to said cannula seal member.

5. A needle set according to claim 1 wherein said hub member is positioned on an end of the outer member, wherein said hub member includes a lumen therethrough, said lumen being in fluid communication with said inner lumen.

6. A needle set according to claim 1 , wherein the inner lumen of said inner member includes a porous filter member disposed therein.

7. A needle set according to claim 6 , wherein said filter member has a pore size that prohibits the passage of body tissue.

8. A needle set according to claim 1 , wherein said sampling portion includes a distal tip and a solid insert having an outer diameter less than an inner diameter of said inner lumen, said sampling portion being engaged with said cannula with said solid insert disposed within a distal end of said inner lumen and said distal tip projecting from said distal end of said cannula, and said sampling cavity being defined through a distal portion of said cannula, and into said solid insert.

9. A needle set according to claim 1 , wherein said cylinder seal member is an O-ring.

10. A needle set according to claim 1 further comprising an advancing mechanism engaged to said inner member; said advancing mechanism being operable to move said outer member relative to said inner member.

11. A needle set according to claim 1 , further comprising a filter member disposed between said inner lumen and said tip member.

12. A needle set according to claim 1 , further comprising an advancing mechanism engaged to said second end of said cylinder and said proximal end of said cannula, said advancing mechanism operable to move said outer member relative to said inner member from the second position to the first position to trap tissue from the biopsy site in the sampling cavity.

13. A needle set according to claim 1 , further including an opening disposed between said cylindrical seal member and said cannula seal member.

14. A needle set according to claim 1 , wherein said needle set will selectively sever tissue as a vacuum is applied to the tissue.

15. A needle set according to claim 1 , wherein said cylinder seal member is moved away from said cannula seal member to increase a vacuum on the tissue.

16. A needle set according to claim 8 , wherein the solid insert is centered within inner lumen.

17. A needle set according to claim 16 , wherein the insert and the inner lumen are sized such that the clearance path prohibits the passage of body tissue.