CA2045018A1

CA2045018A1 - Biopsy forceps

Info

Publication number: CA2045018A1
Application number: CA002045018A
Authority: CA
Inventors: George J. Picha; Dean J. Secrest
Original assignee: Applied Medical Technology Inc
Current assignee: Applied Medical Technology Inc
Priority date: 1990-11-29
Filing date: 1991-06-19
Publication date: 1992-05-30
Also published as: US5082000A

Abstract

BIOPSY FORCEPS

ABSTRACT OF THE DISCLOSURE

A pair of biopsy forceps for capturing, by remote operation, a sample of tissue from an internal location in a patient. The device includes a flexible sheath with a control wire extending therethrough, a pair of jaws movable by the control wire to capture a sample of tissue, and a manual operating means connected at the outer end of the sheath for extending and retracting the control wire. The jaws are mounted at the ends of tongs pivotally mounted in an end housing for movement between open and closed posi-tions. The control wire is connected to lever arms at the rearward end of the tongs by means of two cable lengths connected between the wire and the rearward ends of the lever arms in such a way as to form an effective extension of the respective lever arm.

Description

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BIOPSY FORCEPS

1 BACRGROUND OF T~E INVENTION

2 This invention relates to biopsy orceps for use 3 in various medical applications, wherein a re~otely operable ~ pair of pivotally interconnected levers or torlgs wlth cups or jaws at their outer ends are carried at the end of a thln, 6 elonqated sheath or tube. The CUp5 or ~aws are adapted to 7 be inserted in a patient while ln a closad position and moved 8 to a predetermined internal location. While so positioned, 9 they are manipulated by medical personnel using a cor-trol wire extending through the sheath, to capture a sample of 11 tissue. More particularly, the invention provides a unique, 12 simpli~ied operating mechanism for the levers or tongs that 13 minimizes the space required for manipulating the instrument 14 and that renders the device practically disposa~le in order to reduce the risk of infection that could occur from reuse 16 of the instrument.
17 Various types of biopsy forceps are currently in 18 use in the medical field, such as in endoscopic procedures.
19 These devices generally include gastroscopes, colonoscopes, sigmoidoscopes, and bronchoscopes, for example. Thgy gener-21 ally include a pair o~ levers or tongs that pivot relative 22 to one another between open and closed posltions to bring a 23 pair of cup-shaped ~aws together to capture a sample of 24 tissue. The instrument also includes a long, resilien~, flexible sheath that may be from 100 to 250 centimeters in 26 length.
27 The head assembly that includes the jaws is carried 28 at the end of the flexible sheath and is inserted in the 29 patient at a desired position in accordance with the proce-dure to be performed. The jaws are closed during the inser-31 tion. When the head assembly is suitably positioned, the .1 . ~ , ., , : , 2 ~ 5~

1 ~aws are opened by the medical operator, using an elongated 2 wlre or cahle that extend~ through the sheath. The opera-3 tor then closes the jaws, using the control wire or cable tv 4 capture a sample of tissue between the jaws. In some cases, the instrument has a barbed needle extending forwardly of the 6 open jaws and located between them to "spear" a sample o~
7 tissue and effectively ~pull" it between the jaws as they 8 close. The ~aws are relatively sharp to enable the sample 9 to be cut free ~rom the surrounding tissue.
The biopsy forceps currently in use are generally 11 of complicated design, with numerous components and, as a 12 consequence, are quite expensive. More importantly, these 13 instruments must be carefully sterilized after each use to 14 enable the device to be used safely with another patient.
The sterilizing procedures generally include immersing the 16 contaminated biopsy forceps in chemical sterilizing solutions 17 and/or placing the device in an autoclave. Unfortunately, 18 these conventional sterilizing procedures have recently been 19 found to be imperfect and, upon occasion, the instruments, when reused, have caused the transmission of serious, and 21 even life-threatening, infections. Of particular concern is 22 the risk of transmission of the AIDS virus ~acquired immunity 23 deficiency syndrome) or hepatitis B viruses. Also~ in some 24 instances, the extreme temperatures often present in an autoclave may c~use damage and~or warping of the instrument 26 in such a way as to prevent its proper operation.
27 As a result of the above considerations, it would 28 appear desirable to have the biopsy forceps so designed and 29 assembled as to make it practical to dispvse of them a~ter each use. This would be impractical unless the design of the 31 forceps is sufficiently simplified that disposability becomes 32 cost-effective.

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1 SUMMARY OF T]HE INVENTION
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2 It is among the ob~ectslof the present invention 3 to provlde biopsy forceps of simplified design and cons~ruc-~ tion in order to use the device as a disposable instrument that will be discarded after only one use.
6 Another ob~ect of the inventlon is to improve the 7 operating capability of biopsy forceps by increasin~ the 8 mechanical advantage obtained in the mechanism used to 9 capture and cut away a sample of tissue.
A further ob~ect is to assure that a pair of biopsy 11 forceps may be mo~ed to a closed, ti~sue-capturing condition 12 by a remote operating mechanism without applying excessive 13 force to the ~aws or cups once they have closed and captured 14 the tissue sample.
Still another object of the invention is to reduce 16 the number of parts required and the time involved in the 17 manufacture and assembly of biopsy forceps.
18 These and other objects and advantages are achieved 19 with the unique~biopsy forceps constructed in accordance with the present invention. The forceps include as their primary 21 components a flexible sheath, a control wire or cable extend 22 ing through and movable within the sheath, a pair~of cup-23 shaped jaws movable by the control wire or cable to a closed 24 position to capture a sample of tissue, and a manual operat-ing means connected at the rearward end of the sheath for 26 extending and retracting the control wire or ca~le linearly 27 relative to the sheath.
28 In accordance with the invention, the biopsy 29 forceps further include an end housing connected to the forward end o~ the sheath and de~ining a central passage at 31 its rearward end for receiving the control wire. The end 32 housing also has a pair of forwardly extending bifurcations 33 defininq a slot therebetween that communicates with the , o~

1 central passage. A pivot pin is located in the forward end 2 of the slot extending across the slot perpendicular to the 3 bifurcation~.
A pair of tongs or l~evers are pivotally connected to the forward end of the houc;ing and carry a pair of ~aws 6 at their outer ends, as indicated above. The tongs have 7 rearwardly extending lever arms whereby the tongs may be 8 moved between a closed position, with the ~aws closed, and 9 the lever arms brought together in ad~acent relationship, and an open position wherein the jaws are open and the lever arms 11 are angularly spaced on opposite sides of the end housing.
12 A pair of relatively sti~f, flexible cable lengths are con-13 nected at their inner ends to the control wire to provide a 14 pair of forward extensions from the wire and are rigidly connected at their outer ends to the lever arms in coexten-16 sive relationship therewith so that at least a portion of 17 each cable length forms an extension of the respective lever 18 arm.
19 When the control wire is retracted by the manual operating means, the lever arms are moved to their closed 21 position, wherein the cable lengths are relatively unflexed.
22 When the control wire is extended by the manual operating 23 means, the cable lengths flex radially outward in a bulgin~
24 manner, due to the compressive force applied by the control wire, so as to move the lever arms in opposite directions to 26 their open positions. The outward flexing serv~s both to 27 apply leverdqe to the lever arms and to provide an effective 28 extension of the lever arms~

r, ~0~5()~L8 1 BRIEF DESCRIPTIO~ OF THE D~WINGS

2 FIG. 1 is an elevational view illustrating a pair 3 of biopsy forceps embodying the invention and showing the 4 jaws of the head assembly in their open position;

FIG. 2 is an elevational view similar to FIG. 3, 6 showing the ~aws of the head assembly pivoted to their closed 7 position, and with parts broken away and shown in section for 8 the purpose of illustration;

9 FIG. 3 is a fragmentary, perspective view o~ the biopsy forceps o~ FIGS. 1 and 2 showing the ~aws in their 11 open position;

~12 FIG. 4 is a cross-sectional view, on an enlarged 13 scale, ta~en on the line 4-~ of FIG. 2; and 14 FIG. 5 is a cross-sectional view, on an enlarged scale, taken on ~he line 5-5 of FIG. 2.

16 DESCRIPTIO~ OF THE_PREFERRED EMBODI~E~T

17 Referrinq more particularly to the drawings, and 18 initially to ~IGS. 1 and 2, there is shown in broken ele-19 vation a pair of biopsy forceps 10 embodying the invention, and including as their principal components an elongated, 21 hollow shea~h 11 with a longitudinally mova~le c~ntrol wire 22 12 located therein. The hollow sheath 11 may be from l00 to 23 250 centimeters in lenqth, depending upon the particular 24 endoscopic procedure for which the particular embodiment of the instrument is designed. While relatively stiff, the , , : ~.:

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1 sheath 11 is sufficiently flexible to accommodate the irregu-2 lar path through which the sheal:h must pass when inserted in 3 a patient or endoscope. It is preferably formed of poly-propylene or TEFLON t~binq, and has inner and outer diameters of .08 inch and .035 inch, respectively.
6 The control wire is formed of relatively stiff, 7 .018 inch diameter, stainless steel with a Teflon coating and 8 is sufEiciently flexible to accommodate the directional 9 changes occurrinq during insertion.
~ head assembly 20 is located at the orward end 11 of the sheath and an operating assembly 50 is located at the 12 rearward end. The head assembly is adapted for location at 13 a predetermined position inside the patient, and may be 14 manipulated to capture a sample of tissue which is separated and then removed from the patient for analysis. The operat-16 ing assembly 50 is adapted to enable the operator to manipu-17 late the head assembly externally of the patient.
18 Located at the forward end of the control wire 12 19 is a stainless steel Y-connector 13 which serves to connect the control wire 12 to a pair of stiff, flexible cable 21 lengths 14 and 15 with their rearward ends 16 and 17 secured 22 to the connector in a generally parallel relation to the end 23 of the control wire 12.
24 The front ends 18 and 1~ of the cable lengths are used to operate the head assembly 20 in a manner to be 26 described below. The cable lengths may be, for example, .012 27 inch wound wire cable.
28 The head assembly 20 inc~udes a relatively thin, 29 elongated, generally cylindrical housing 21 formed of metal, with a hollow connector plug 22 at its rearward end adapted 31 to be riqidly connected to the hollow sheath 11. The hollow 32 connector plug is formed with circumferential ribs or barbs, 33 as shown in FIG. 2, to assure a firm connection. The respec-34 tive end of the hollow sheath is provided with internal : , , :: i 7 ~ s~

1 threads to facilitate the connection. During attachment, the 2 end of the sheath is turned so that the internal threads 3 engage the circumferential ribs or barbs on the plug 22 and, 4 although a threaded connection is not achieved, the result S serves to provide a firm grip between the plug and the 6 sheath. This prevents inadvertent disconnectlon as a result 7 of axial or parallel forces.
8 At the forward end o~ the housin~ 21 are a pair of 9 parallel bifurcations 23 and 24 which define an elonqated slot 25 therebetween. The rearward end of the slot 25 11 communicates with a central bore 26 that extends entirely 12 through the rearward end of the housinq 21 and is adapted to 13 receive the ~orward end of the control wire 12.
14 Rigidly mounted to the bifurcations 23 and 24 and extending laterally across the slot 25 is a pivot pin 27.
16 A stainless steel needle 28 with a barb 29 or spacer located 17 thereon extends forwardly from the end of the housing 21 and 18 its rearward end is rigidly mounted to the central portion 19 of the pivot pin 27. The barbed needle 28 may not be used in some embodiments of the biop~y forceps, depending upon the 21 particular application. The purpose of the barbed needle is 22 to spear a sample of tissue and hold it in position to be cut 23 and captured by the head assembly 20.
24 A pair of tongs or levers 30 and 40 are pivotally connected to the housing 21. These are shown pivoted to 26 their open position in FIGS. 1 and 3 and to their closed 27 position in FIGS. 2, 4, and 5. Each lever 30 and 40 has a 28 front arm 31 and 41, respectively, whih carries a cup or jaw 29 32, 42, which have relatively sharp edge portions that can be used to cut and capture a sample of tissue to be analyzed.
31 The particular shape of the cup may vary from one embodiment 32 of the invention to another to suit the particular applica-33 tion.

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~ 2~ 0~3 1 Each of the tongs also has a rearward arm 33, ~3 2 connected to the front end 18, 19 of one of the two cable 3 len~ths 1~ and 15. The rearwarcl arms 33 and 43 are so shaped 4 that when they are pivoted to the closed posltion (FIG. ~), they fit together side by side within the slot 25 and also 6 accommodate the front ends 18 and 19 of the two cable lengths 7 14 and 15. The rear arms 33 and q3 have connector portions 8 to receive the rearward ends of the cable length~ 14 and 15, 9 which are soldered thereto to form a relatively rigid connec- t~
tion with the ends of the cable lengths extending generally 11 parallel to the arms 33 and 43.
12 The rear arms have notches or platforms 3~, ~4 cut 13 therein in planes extending longitudinally relative to the 14 arms. The forward ends of these notches or platforms 34, 44 have a shoulder 35, 45 at their lnner ends. The platforms 16 34 and 44 provide a seat for the ends of the cable lengths 17 14 and lS, which are soldered or welded in place thereon.
~8 The ends of the cable lengths 14 and lS are positioned in 19 abutment with the shoulders 35 and 45 to assure accurate positioning of the cable lenqths. This arrangement assures 21 that the effective operating portions of the cable lengths 22 14 and 15 that extend between the ends of the lever arms 33 23 and 43 and the Y-connector 13 are exactly the same~ -24 The rearward arms 33 and 43 also have cooperatïng longitudinally extending flange portions 36 and 46 formed 26 therein and extending inward from the respective inner side 27 faces. When the levers 30 and 40 are moved to their closed 28 position, these flange portions 36 and 46 engage one another 29 to provide a limit position for the levers or tongs. This limit position is reached just as the Saws or cups reach 31 their closed position. Accordingly, any additional force 32 applied to the levers 30 and 40 by retraction of the c~ntrol 33 wire 12 will be transmitted to the flan~es 36, 46 and not to 34 the jaws or cups. This arrangement assures that any use of ,:
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1 excessive retraction force wilL not result ln damaqe to the 2 cups or the forwardly extending lever arms.
3 It will al~o be noted that the CUp5 32 and 42 each 4 have a central opening 37, 47 forrned therein to permit the escape of liquid th~t could accumulate in the cups during the 6 closing and tlssue capturing movement.
7 Referring to FIG. 1, it will be apparent that 8 because of the manner of connectlon of the cable lengths to 9 the tongs, when the tongs are moved to their open position the cable lengths must bulge radially outward and make a 11 gradual bend back into alignment with their lnner ends, which 12 are qenerally parallel to the control wire 12. The radial 13 bulging, however, is limited so that it is no greater than 14 the radial ~istance that the ~aws 32 and 42 extend when ln their open position. Accordingly, the radial bulging or 16 bending of the cable lengths 14 and 15 will not displace the 17 surrounding tissue any more than that caused by movement of 18 the jaws.
19 The stiffness of the cable lengths must be careful-ly controlled so that the flexing of the cable lengths during 21 the opening movement will not be unduly resisted. On the 22 other hand, the cable lengths must be sufficiently stiff that 23 forward movement of the control wire will transmit-a suffi-24 cient compressive force relative to the lever arms to obtain sufficient opening of the ~aws. The cable lengths actually 26 serve to extend the length of the effective lever arm to 27 which orce is applied.
28 Referring to FIG. 1. it will be sean that the 29 distance from the pivot axis to the general location at which force is applied by movement of the control wire, and thus 31 the inner ends of the ca~le lengths, i5 significantly beyond 32 the ends of the rearward arms 33 and 43. This feature 33 enables the l,ever system to obtain optimum mechanical advan-34 tage in a minimum of available space.

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1 o ~50~8 l The closing movement of the ~aw~ 32 and 42 ls 2 obtained by retraction o the control wire relative to the 3 housing 21. This pu115 the cable lengths l4 and lS in a 4 rearward direction, thus moving the lever arms 33 and 43 inwardly to close the ~aws in a position lndicated in FIG, 6 2. It will be noted that in FIG. 2, the cable lengths are 7 generally under tension rather than compression, and the 8 resulting forces tend to hold the ~aws 32 and ~2 in their 9 closed position with a sample of t1ssue captured therein.
The operating assembly 50 located at the rearward ll end of the hollow sheath ll includes a hollow end cap 51 12 which is adapted for connection to the sheath ll, such as by 13 swaging. The rear end of the hollow end cap has a socket l4 which receives a rear housing 52 wikh a thumb ring 53 formed at its outer end. The rear housing has a central, cylindri-16 cal body 54 with an axially extending slot 55 formed therein.
17 Slidably located over the cylindrical body 54 is a hollow 18 finger grip 60 with a lateral pin extendinq therethrough and l9 received in the axial slot 55. The inner end of the control wire 12 is connected to the pin 61 so that axial movement of 21 the finger grip 60 moves the control wire 12 in a longitudi-22 nal d~rection within the hollow sheath.
23 Thus, in the operation of the biopsy for~eps thus 24 described, the head assembly 20 is moved to its closed position by retracting the finger grip 60 and then inserted 26 into the patient to a desired position for obtaining a sample 27 of tissue. When the head assembly is so positioned, the 28 finger qrip 60 is moved Eorward relative to the thumb ring 29 53 to move the control wire forward and apply a compressive force against the cable lengths l4 and 15, causing them to 31 bulge radially outward. This compressive force and resultant 32 radial movement serve to open the tongs and move the cups or 33 jaws to the open position shown in FIG. l. At the same time, 34 the needle 28 may be moved forward by further advance of the : , :
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1 head assembly to spear a sample of tissue and retain it for 2 capture.
3 With the jaws fully open, the operator moves the ~ finq~r grip to the rear relative to the th~lmb ring to retract the control wire, and thus apply a tensile force to the cable 6 lengths. This unflexes the cable lengths and causes closing 7 of the jaws 32 and 42 to the positlon shown in FIG. 2. At 8 the same time, a sample of tissue is cut by the closing 9 motion and captured within the ~aws or cups.
It will be noted that once the ~aws or cups reach 11 their closed position, the flanges 36 and ~6 formed ln the 12 rearward arms 33 and ~3 will engage one another to limit 13 further movement o~ the tongs. Accordingly, when thls 14 condition is reached, any force applied to the control wire will be applied through the ~langes 36 and 46 to the rearward 16 ends of the tongs, and not to the cups or jaws.
17 Then, the head assembly is retracted, with the cups 18 tightly held in their closed position by means of the finger 19 grip 60 and the entire head assembly and hollow sheath are removed from the patient.
21 While the invention has been shown and described 22 with respect to a specific embodiment thereof, this is 23 intended for the purpose of illustration rather tha~ limita-2~ tion, and other variations and modifications of the specific embodiment herein shown and described will be apparent to 26 those skilled in the art all within the intended spirit and 27 scope of the invention. Accordingly, the patent is not to 28 be limited in scope and effect to the specific embodiment 29 herein shown and described nor in any other way that is inconsistent with the extent to which the state o~ the art 31 has been advanced by the inven~ion.

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Claims

1. Biopsy forceps including a flexible sheath, a control wire extending through and movable within the sheath, a pair of cup-shaped jaws movable by the control wire to a closed position to capture a sample of tissue, and manual operating means connected at the rearward end of the sheath for extending and retracting the control wire linearly relative to said sheath, said forceps further comprising:
an end housing connected to the forward end of said sheath and defining a central passage for receiving said control wire;
a pair of tongs pivotally connected to the forward end of said housing and having said jaws connected to their respective outer ends, said tongs each having a rearwardly extending lever arm whereby said tongs are movable about a common pivot axis between a closed position wherein said jaws are closed to capture a sample of tissue and an open position wherein said jaws are open and said lever arms extend radially outward in opposite directions; and a pair of relatively stiff, flexible cable lengths connected at their inner ends to said control wire and rigidly connected at their outer ends respectively to said lever arms in coextensive relation therewith so that at least a portion of each cable length forms an extension of the respective lever arm, whereby when said control wire is retracted by said manual operating means, said lever arms are moved to their closed position and when said control wire is extended by said manual operating means said cable lengths flex out-wardly in opposite directions to move said lever arms to their open position.

2. A device as defined in claim 1, wherein said end housing has a pair of forwardly extending bifurcations defining a slot therebetween that communicate with said central passage, said pivot axis extending across said slot between said bifurcations.

3. A device as defined in claim 1, wherein said cable lengths are formed of stranded stainless steel wire.

4. A device as defined in claim 1, wherein said rearwardly extending lever arms define a platform facing radially outward parallel to the pivot axis and a shoulder at the inner end of said platform, said forward portions of said cable lengths being fastened to said platforms with their ends butting against said shoulders.

5. A device as defined in claim 4, wherein said cable lengths are formed of stranded stainless steel wire filaments and are soldered to said platforms.

6. A device as defined in claim 1, wherein the rearward end of said end housing has a rearwardly extending plug portion with circumferential barbs formed thereon and being adapted to receive the forward end of said sheath.

7. A device as defined in claim 6, wherein the end portion of said sheath received on said plug has internal threads formed therein.

8. A device as defined in claim 1, wherein the rearward end of each of said lever arms is provided with a stop means, said respective stop means of said arms being adapted to engage one another when said tongs are moved to their closed position whereby any additional retraction force applied through said control wire will be applied only to said stop means.

9. A device as defined in claim 8, wherein said stop means comprise flanges formed on said rearward lever arms and extending inwardly from the inner sides of said lever arms whereby they engage one another when said tongs are closed.

10. Biopsy forceps including a flexible sheath, a control wire extending through and movable within the sheath, a pair of cup-shaped jaws movable by the control wire to a closed position to capture a sample of tissue, and manual operating means connected at the rearward end of the sheath for extending and retracting the control wire linearly relative to said sheath, said forceps further comprising:
an end housing connected to the forward end of said sheath and defining a central passage for receiving said control wire;
pivot means in the forward end of said end housing;
a pair of tongs pivotally connected to the forward end of said housing by said pivot means and having said jaws connected to their respective outer ends, said tongs each having a rearwardly extending lever arm whereby said tongs are movable between a closed position wherein said jaws are closed to capture a sample of tissue and an open position wherein said jaws are open and said lever arms extend radially outward in opposite directions; and a pair of relatively stiff, flexible cable lengths connected at their inner ends to said control wire and rigidly connected at their outer ends respectively to said lever arms, means formed on each rearward lever arm defining an axially extending, outwardly facing surface parallel to said pivot axis and means defining an outwardly extending shoulder at the inward end of said axially extending surface, whereby the outward portion of each cable length may be secured to a respective axially extending surface with its inner end abutting said shoulder, whereby when said control wire is retracted by said manual operating means, said lever arms are moved to their closed position and when said control wire is extended by said manual operating means said cable lengths flex out-wardly in opposite directions to move said lever arms to their open position.

11. A device as defined in claim 10, wherein said end housing has a pair of forwardly extending bifurcations defining a slot therebetween that communicate with said central passage, said pivot axis extending across said slot between said bifurcations.

12. A device as defined in claim 10, wherein said cable lengths are formed of stranded stainless steel wire.

13. A device as defined in claim 10, wherein the rearward end of said end housing has a rearwardly extending plug portion with circumferential barbs formed thereon and being adapted to receive the forward end of said sheath.

14. A device as defined in claim 13, wherein the end portion of said sheath received on said plug has internal threads formed therein.

15. A device as defined in claim 10, wherein the rearward end of each of said lever arms is provided with a stop means, said respective stop means of said arms being adapted to engage one another when said tongs are moved to their closed position whereby any additional retraction force applied through said control wire will be applied only to said stop means.

16. A device as defined in claim 15, wherein said stop means comprise flanges formed on said rearward lever arms and extending inwardly from the inner side of said lever arms whereby they engage one another when said tongs are closed.