Biopsy needle with cauterization feature

A biopsy needle cauterizes the wound caused by the taking of a tissue specimen and the tissues in contact with the biopsy needle prior to withdrawal of the biopsy needle from a person, thereby minimizing bleeding and preventing the proliferation of any existing cancer cells along the path of insertion and withdrawal of the biopsy needle from the body. In contrast with existing biopsy needles, the tissue is excised by retraction of the stylet into the cannula, with the cutting edge being at the junction of the upper surface of the stylet and the front wall of the recess which holds the tissue specimen, rather than excising the tissue by sliding the cannula forward over the recess in the stylet with the cutting means at the leading edge of the cannula.

BACKGROUND OF THE INVENTION 
This invention relates generally to biopsy needles, and more particularly 
to a biopsy needle with an improved capability for excising tissue 
specimens and for cauterizing the wound and the tissue in contact with the 
needle after the tissue specimen has been taken. 
Various types of biopsy devices are known. Patents which disclose manual, 
spring operated biopsy devices include: U.S. Pat. No. 4,917,100 (Nottke) 
and U.S. Pat. No. 4,733,671 (Mehl). These biopsy devices comprise a 
cannula which is a hollow, rod-shaped member, and a stylet which is 
slidably mounted in the cannula. With the stylet positioned so that its 
end tip is adjacent the end of the cannula, the biopsy needle is inserted 
into the tissue of a person. The stylet has a notch or recess for holding 
the tissue specimen near its end, adjacent to the piercing tip. To take 
the tissue specimen, the stylet is then thrust forward into the area in 
which the specimen is desired. The cannula which has a sharp edge at its 
end, is then moved forward toward the end of the stylet, causing the sharp 
end of the cannula to excise tissue which is then held in the recess of 
the stylet. The biopsy device, with the specimen enclosed in the recess, 
is then removed from the body of the patient. 
Devices which apply cauterizing heat to the body are shown in U.S. Pat. No. 
4,016,881 (Rioux et al.) and U.S. Pat. No. 3,938,527 (Rioux et al.) which 
discloses a gun-shaped device which inserts electrodes into the body for 
cauterizing of tubes; and U.S. Pat. No. 4,776,334 (Prionas) which 
discloses a device for cauterizing tumors. 
Other patents including U.S. Pat. No. 1,813,902 (Bovie); U.S. Pat. No. 
3,648,001 (Anderson et al.); and U.S. Pat. No. 2,275,167 (Bierman) 
disclose surgical instruments which use electrical energy for 
cauterization or for cutting purposes. 
My patent, U.S. Pat. No. 5,295,990, discloses a tissue sampling and removal 
device which comprises a pair of cutting jaws with a heat insulated inner 
surface defining a chamber for retaining the tissue cut by the jaws. A 
conductor carries electrical energy which heats the device, thereby 
cauterizing the tissues surrounding the jaws prior to removal of the 
excised tissue specimen. 
Existing biopsy devices have several major shortcomings. The cutting of the 
tissue to excise a tissue specimen by moving the sharp end of the cannula 
forward over and past the recess in the stylet causes bunching of tissue 
and cutting which is often ragged and not sharp. Furthermore, if the 
biopsy needle is used to excise tissue specimens from a suspected cancer 
tumor or cancer infected area of the body, withdrawal of the needle after 
the specimen has been taken could well leave a trail of displaced cancer 
cells in the path of the removal of the biopsy needle, thereby 
proliferating the locations of the cancer. 
In view of the foregoing, a biopsy needle with an improved cutting 
capability and which prevents the spread of cancer cells during the taking 
of tissue specimens as provided by the instant invention is needed. 
OBJECTS OF THE INVENTION 
Accordingly, it is the general object of the instant invention to provide a 
biopsy needle which improves upon, and which overcomes the shortcomings 
of, existing biopsy needles. 
It is a further object of the instant invention to provide a biopsy needle 
which has improved cutting capability as compared to existing biopsy 
needles. 
It is yet a further object of the instant invention to provide a biopsy 
needle which cauterizes the wound caused by the insertion and removal of 
the needle to minimize bleeding. 
It is still yet a further object of the instant invention to provide a 
biopsy needle which cauterizes the tissue in contact with the needle after 
the taking of tissue specimens to prevent the spread of any existing 
cancer cells in the region of the location at which the specimen has been 
taken and along the path of removal of the biopsy needle. 
It is another object of the instant invention to provide a biopsy needle 
which uses electrical current to heat the biopsy needle for cauterization 
of the wound and the tissues in contact with the biopsy needle after the 
taking of tissue specimens. 
SUMMARY OF THE INVENTION 
These and other objects of the instant invention are achieved by providing 
a biopsy needle which comprises a cannula, a stylet slidingly held in the 
cannula, means for inserting the needle into a person, means for excising 
tissue from the person, and means for removing the needle from the person. 
Cauterization means are provided to cauterize the wound to minimize 
bleeding and to cauterize the tissue in contact with the biopsy needle to 
prevent the spread of any existing cancer cells surrounding the wound 
along the path of removal of the biopsy needle after the tissue specimen 
has been taken. 
An improved cutting means is provided by incorporating a sharp edge at the 
junction between the top surface of the stylet and the front wall of the 
recess in the stylet which holds the tissue specimen. Instead of moving 
the cannula forward toward the piercing end of the stylet to excise the 
tissue specimen, as is done with conventional biopsy needles, the stylet 
with the sharp edge near the end of the stylet is moved back toward the 
cannula to excise the tissue specimen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now in greater detail to the various figures of the drawing, 
wherein like reference characters refer to like parts, there is shown in 
FIGS. 1-3 the biopsy needle 2 of the instant invention. The biopsy needle 
2 comprises a hollow, rod-shaped cannula 4 and a stylet 6, which is 
slidingly held in the cannula 4. The stylet 6 has an upper surface 8, a 
lower surface 10 and a proximal end 12. The proximal end 12 comprises a 
sloped end surface 16 which extends downwardly from the upper surface 8 to 
the lower surface 10. A piercing tip 14 is formed at the junction between 
the sloped end surface 16 and the lower surface 10, for insertion of the 
biopsy needle 2 into a person. 
As can be seen in FIGS. 2 and 3, the cannula 4 has an upper surface 18, a 
lower surface 20, and a proximal end 21. The proximal end 21 comprises a 
sloped end surface 24 extending downwardly from the upper surface 18 to 
the lower surface 20 and a piercing tip 22 formed at the junction between 
the sloped end surface 24 and the lower surface 20. 
The stylet 6 has a notch or specimen holding recess 26 extending downward 
from the upper surface 8. As can be seen in FIG. 1, the excised tissue 
specimen 28 is held in the specimen holding recess 26 after the specimen 
has been taken and the stylet 6 has been retracted back into the cannula 
4. 
The specimen holding recess 26 comprises an insulation bottom wall 30, a 
insulation front wall 34 and an insulation rear wall 36. Attached to the 
inner surface of the cannula 4 is an insulation circumferential wall 32. 
The walls 30, 32, 34 and 36 comprise insulating material which prevents 
the conduction of heat from outside the walls into the recess. Thus, when 
cauterization heat is applied to the biopsy needle, the excised tissue 
specimen 28 is protected from the heat. The walls 30, 32, 34 and 36 form a 
chamber (see FIGS. 1 and 4), which insulates the excised tissue specimen 
28 from the cauterization heat which is applied to the biopsy needle 2 
prior to removal of the biopsy needle from the patient, as will be 
explained later. 
The procedure for the taking of the tissue specimen 28 and the 
cauterization of the wound and surrounding tissues will now be explained. 
Initially, the stylet 6 is retracted fully into the cannula 4 so that the 
piercing tips 14 and 22 are adjacent. As can be seen in FIG. 2, the stylet 
6 is then thrust forward in the direction D.sub.1 of the arrow to extend 
the stylet 6 forward from the cannula 4 into the region of the person from 
which a tissue specimen 28 is desired. The arrow in FIG. 2 shows the 
forward direction D.sub.1 of the stylet 6 when the stylet 6 is extended 
forward. 
FIG. 3 shows the surrounding tissue 40 of the person, a part of which fills 
the specimen holding recess 26. As can be seen in the figure, the 
retraction of the stylet 6 back into the cannula 4 in the direction of the 
arrow D.sub.2 excises the tissue specimen 28 from the body tissues of the 
person. The stylet 6 has a sharp cutting edge 38 formed at the junction 
between the insulated front wall 34 and the top surface 8 which cuts into 
the tissue 40 to excise the tissue specimen 28. 
FIG. 1 shows the stylet fully retracted back into the cannula 4 with the 
excised tissue specimen 28 held in the specimen holding recess 26. As 
stated previously, an insulation chamber is formed by the insulation walls 
30, 34 and 36 of the recess 26 and the insulation circumferential wall 32 
to protect the excised tissue specimen 28. 
The biopsy needle also includes a conductor 42 which applies electrical 
current to the biopsy needle 2 to heat the biopsy needle and thereby 
cauterize the wound caused by the excising of the tissue specimen and the 
tissue in contact with the biopsy needle 2 as it is removed from the body. 
The procedure is to re-thrust the biopsy needle 2 forward into the area 
from which the specimen was taken, then to apply cauterization heat before 
and while removing the biopsy needle 2 from the patient. This 
cauterization minimizes the bleeding of the wound caused by the insertion 
of the biopsy needle 2 and the excising of the tissue specimen 28. In 
addition, the cauterization kills existing cancer cells, preventing the 
proliferation of cancer cells, if they are present in the region in which 
the excised tissue specimen 28 has been taken, along the path of the 
removal of the biopsy needle from the body of the patient. 
As can be further seen in FIG. 1, the inner surface of the cannula 4 has a 
ring of insulation 43. The small segment of the inner surface of the 
cannula 4 at A is not insulated. Therefore, the current can flow through 
the conductor 42 into the stylet 6 and then, at the area A, to the cannula 
4 which acts as a return for the current. 
A biopsy needle has been described which operates in a different manner 
than conventional biopsy needles and which provides a cleaner cutting 
technique than conventional biopsy needles. The biopsy needle 2 of the 
instant invention takes the excised tissue specimen 28 by retracting the 
stylet back into the cannula with a cutting edge at the junction between 
the top wall of the stylet and the front wall of the recess. By contrast, 
conventional biopsy needles take a tissue specimen by using a cutting edge 
at the front edge of the cannula and by thrusting the cannula forward to 
excise the tissue specimen 28 and to cover the recess 26 which holds the 
tissue specimen. Also, the biopsy needle of the instant invention 
automatically cauterizes the wound and the tissue in contact with the 
biopsy needle after the tissue specimen 28 has been taken and prior to 
removal of the biopsy needle from the patient, to minimize bleeding and to 
prevent the proliferation of cancer cells along the path of removal of the 
biopsy needle 2.