Abstract:
An endoscopic bioptome includes a flexible coil having a lumen with an axially displaceable wire extending therethrough. The proximal ends of coil and wire couple to a manual actuator for axially displacing one of the coil and wire relative to the other. The distal end of the coil couples to either a jaw assembly or a cylinder. The jaw assembly includes a pair of jaws each having a distal jaw cup having a proximal neck and a relatively narrow bent resilient arm. The distal end of the wire couples to the other of the cylinder or the jaw assembly. The cylinder is slidable over the jaw assembly. Axial movement of either the wire relative to the coil or vice versa moves the cylinder over the arms of the jaws and over the necks of the jaw cups, thereby forcing the jaw cups together in a biting action.

Description:
This is a division of application Ser. No. 08/960,214, filed Oct. 29, 1997, incorporated herein by reference. 
     This application is related to co-owned U.S. application Ser. No. 08/189,937 filed Feb. 1, 1994, co-owned U.S. Ser. No. 08/584,801 filed Jan. 11, 1996, co-owned U.S. Ser. No. 08/440,326 filed May 12, 1995, and co-owned U.S. Ser. No. 08/412,058 filed Mar. 28, 1995, each of which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to endoscopic surgical instruments. More particularly, this invention relates to an instrument for taking biopsy tissue samples. 
     2. State of the Art 
     Endoscopic biopsy procedures are typically performed with an endoscope and an endoscopic biopsy forceps device (bioptome). The endoscope is a long flexible tube carrying fiber optics and having a narrow lumen through which the bioptome is inserted. The bioptome typically includes a long flexible coil having a pair of opposed jaws at the distal end and manual actuation means at the proximal end. Manipulation of the actuation means opens and closes the jaws. During a biopsy tissue sampling operation, the surgeon guides the endoscope to the biopsy site while viewing the biopsy site through the fiber optics of the endoscope. The bioptome is inserted through the narrow lumen of the endoscope until the opposed jaws arrive at the biopsy site. While viewing the biopsy site through the fiber optics of the endoscope, the surgeon positions the jaws around a tissue to be sampled and manipulates the actuation means so that the jaws close around the tissue. A sample of the tissue is then cut and/or torn away from the biopsy site while it is trapped between the jaws of the bioptome. Keeping the jaws closed, the surgeon withdraws the bioptome from the endoscope and then opens the jaws to collect the biopsy tissue sample. 
     A biopsy tissue sampling procedure often requires the taking of several tissue samples either from the same or from different biopsy sites. Unfortunately, most bioptomes are limited to taking a single tissue sample, after which the device must be withdrawn from the endoscope and the tissue collected before the device can be used again to take a second tissue sample. The single-sample limitation of most bioptomes is due to the limited space between the biopsy forceps jaws. Several attempts have been made to provide an instrument which will allow the taking of several tissue samples before the instrument must be withdrawn and the samples collected. Problems in providing such an instrument include the extremely small size required by the narrow lumen of the endoscope and the fact that the instrument must be flexible in order to be inserted through the lumen of the endoscope. Thus, several known multiple sample biopsy instruments are precluded from use with an endoscope because of their size and rigidity. These include the “punch and suction type” instruments disclosed in U.S. Pat. No. 3,989,033 to Halpern et al. and U.S. Pat. No. 4,522,206 to Whipple et al. Both of these devices have a hollow tube with a punch at the distal end and a vacuum source coupled to the proximal end. A tissue sample is cut with the punch and suctioned away from the biopsy site through the hollow tube. It is generally recognized, however, that suctioning tissue samples through a long narrow flexible bioptome is extremely difficult and fraught with problems. 
     Efforts have been made to provide a multiple sampling ability to an instrument which must traverse the narrow lumen of an endoscope. These efforts have concentrated on providing a cylindrical storage space at the distal end of the instrument wherein several tissue samples can be accumulated before the instrument is withdrawn from the endoscope. U.S. Pat. No. 4,651,753 to Lifton, for example, discloses a rigid cylindrical member attached to the distal end of a first flexible tube. The cylindrical member has a lateral opening and a concentric cylindrical knife blade is slidably mounted within the cylindrical member. A second flexible tube, concentric to the first tube is coupled to the knife blade far moving the knife blade relative to the lateral opening in the cylindrical member. A third flexible tube having a plunger tip is mounted within the second flexible tube and a vacuum source (a syringe) is coupled to the proximal end of the third tube. A tissue sample is taken by bringing the lateral opening of the cylindrical member upon the biopsy site, applying vacuum with the syringe to draw tissue into the lateral opening, and pushing the second flexible tube forward to move the knife blade across the lateral opening. A tissue sample is thereby cut and trapped inside the cylindrical knife within the cylindrical member. The third flexible tube is then pushed forward moving its plunger end against the tissue sample and pushing it forward into a cylindrical storage space at the distal end of the cylindrical member. Approximately six samples can be stored in the cylindrical member, after which the instrument is withdrawn from the endoscope. A distal plug on the cylindrical member is removed and the six samples are collected by pushing the third tube so that its plunger end ejects the samples. 
     The device of the Lifton patent suffers from several recognizable drawbacks. First, it is often difficult to obtain a tissue sample laterally of the device. Second, in order to expedite the obtaining of a lateral sample, a syringe is used to help draw the tissue into the lateral opening. However, this causes what was once a two-step procedure (position and cut), to become a three-step procedure (position, suction, cut). In addition, the use of a syringe requires an additional hand. Third, the Lifton patent adds a fourth step to the biopsy procedure by requiring that the tissue sample be pushed into the storage space. Thus, in all, the Lifton patent requires substantial effort on the part of the surgeon and an assistant and much of this effort is involved in pushing tubes, an action which is counter-intuitive to classical biopsy sampling. The preferred mode of operation of virtually all endoscopic tools is that a gripping action at the distal end of the instrument is effected by a similar action at the proximal end of the instrument. Classical biopsy forceps jaws are closed by squeezing a manual actuation member in a syringe-like manner. 
     A more convenient endoscopic multiple sample biopsy device is disclosed in U.S. Pat. No. 5,171,255 to Rydell. Rydell provides a flexible endoscopic instrument with a knife-sharp cutting cylinder at its distal end. A coaxial anvil is coupled to a pull wire and is actuated in the same manner as conventional biopsy forceps. When the anvil is drawn into the cylinder, tissue located between the anvil and the cylinder is cut and pushed into a storage space within the cylinder. Several samples may be taken and held in the storage space before the device is withdrawn from the endoscope. While the device of Rydell is effective in providing a multiple sample tool where each sample is obtained with a traditional two-step procedure (position and cut), it is still limited to lateral cutting which is often problematic. Traditional biopsy forceps provide jaws which can grasp tissue frontally or laterally. Even as such, it is difficult to position the jaws about the tissue to be sampled. Lateral sampling is even more difficult. 
     Related application Ser. No. 08/189,937 discloses an endoscopic multiple sample bioptome having a hollow outer member and an axially displaceable inner member extending therethrough. The proximal ends of the outer and inner members are coupled to an actuator for axially displacing one relative to the other. The distal end of the outer member is coupled to one of a cylinder having a sharp distal edge and a jaw assembly, while the distal end of the inner member is coupled to the other. The jaw assembly includes a pair of opposed, preferably toothed, jaw cups each of which is coupled by a resilient arm to a base member. The resilient arms are bent to urge the jaws away from each other. The base member is mounted inside the cylinder and axial movement of the jaw assembly and cylinder relative to each other draws the resilient arms into the cylinder and brings the jaw cups together in a biting action. Depending on the geometry of the resilient arms, however, when the cylinder is moved over the arms, they may tend to bow inward and prevent a complete closing of the jaws. This results in a less than optimal biting action. 
     Related application Ser. No. 08/412,058 discloses an endoscopic multiple sample bioptome having enhanced biting action where the biting force at the jaws is substantially increased. In some cases, however, too much biting force at the jaws may be undesirable. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an endoscopic bioptome which has controlled jaw engagement and biting force. 
     It is also an object of the invention to provide an endoscopic multiple sample bioptome of controlled jaw engagement and biting force which is easy to operate. 
     In accord with these objects which will be discussed in detail below, the endoscopic bioptome of the present invention includes a relatively long flexible coil having a lumen with an axially displaceable wire extending therethrough. The proximal ends of the flexible coil and wire are coupled to a manual actuation means for axially displacing one of the flexible coil and wire relative to the other. According to a first embodiment of the invention, the distal end of the flexible coil is coupled to a jaw assembly and the distal end of the wire is coupled to a cylinder which is slidable over the jaw assembly. The wire is also provided near the distal end with a coaxial stopping band. The jaw assembly includes a pair of jaws each having a distal jaw cup having a proximal neck and a relatively narrow bent resilient mounting arm. The mounting arm of each jaw is coupled to the distal end of the coil by a washer (or retaining sleeve) through which a hollow threaded screw is threaded into the coil. The distal end of the wire extends through the hollow threaded screw and is coupled to the cylinder which is slidable over the jaw assembly. Axial movement of the wire relative to the coil moves the cylinder over the bent resilient arms of the jaws and over the necks of the jaw cups, thereby forcing the jaw cups together in a biting action. However, axial movement of the wire is limited by the coaxial stopping band which is arranged to abut the hollow screw as soon as the jaws close. The distance between the stopping band and the proximal end of the hollow screw is preferably equal to the distance between the distal end of the cylinder and the point on the jaw cups where the distal end of the cylinder lies when the jaws are closed. 
     According to a second embodiment of the invention, the distal end of the coil is coupled to a cylinder and the distal end of the wire is coupled to a jaw assembly which is slidable into and out of the cylinder. The jaw assembly includes a pair of opposed jaw cups, each of which is coupled by a narrow arm to a base member which resides inside the cylinder. The narrow arm of each jaw is a resilient member which includes a portion which is bent away from the longitudinal axis of the cylinder in order to locate the jaw cups substantially apart from each other. Axial movement of one of the jaw assembly and cylinder relative to the other draws the arms of the jaws into the cylinder or moves the cylinder over the arms of the jaws to bring the jaw cups together in a biting action. 
     In accord with the second embodiment of the invention, the cylinder is provided with an annular stopping crimp which prevents further proximal movement of the jaw assembly (or distal movement of the cylinder) once the jaws have closed. The distance between the stopping crimp and the proximal end of the jaw assembly is preferably equal to the distance between the distal end of the cylinder and the point on the jaw cups where the distal end of the cylinder lies when the jaws are closed. 
     According to a third embodiment of the invention, the distal end of the coil is coupled to a jaw assembly and the distal end of the wire is coupled to a cylinder which is slidable over the jaw assembly. The jaw assembly includes a pair of jaws each having a distal jaw cup having a proximal neck and a relatively narrow bent resilient mounting arm. The mounting arm of each jaw is coupled to the distal end of the coil by a washer (or retaining sleeve) through which a hollow threaded screw is threaded into the coil. The distal end of the wire extends through the hollow threaded screw and is coupled to the cylinder which is slidable over the jaw assembly. Axial movement of the wire relative to the coil moves the cylinder over the bent resilient arms of the jaws and over the necks of the jaw cups, thereby forcing the jaw cups together in a biting action. 
     In accord with the third embodiment of the invention, a portion of the coil adjacent to the jaw assembly is ground to a reduced diameter and the cylinder is provided with a radially inward flange. Axial movement of the cylinder is limited by the flange which abuts the washer (or retaining sleeve) of the jaw assembly as soon as the jaws close. 
     According to a fourth embodiment of the invention, each jaw cup is provided a step on its outer surface which limits distal movement of the cylinder and/or proximal movement of the jaw assembly as soon as the jaws close. 
     Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view in partial section of the proximal end of a bioptome according to the invention; 
     FIG. 2 is an enlarged partially transparent side elevation view of the distal end of a first embodiment of a bioptome of the invention with the jaws open; 
     FIG. 3 is an enlarged transparent top view of the distal end of the bioptome of FIG. 2 with the jaws open; 
     FIG. 4 is a view similar to FIG. 2, but with the jaws closed; 
     FIG. 5 is a view similar to FIG. 2 of a second embodiment of the invention; 
     FIG. 6 is a view similar to FIG. 4 of the second embodiment of the invention; 
     FIG. 7 is a view similar to FIG. 2 of a third embodiment of the invention; 
     FIG. 8 is a view similar to FIG. 4 of the third embodiment of the invention; 
     FIG. 9 is a view similar to FIG. 2 of a fourth embodiment of the invention; and 
     FIG. 10 is a view similar to FIG. 4 of the fourth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1 through 4, a multiple sample bioptome  10  according to the invention includes a proximal handle  12  and a distal end effector  14 . A long flexible coil  16  having an axially displaceable control wire  18  extending therethrough couples the handle  12  and the end effector  14 . The coil  16  is preferably covered with a PTFE, FEP or polyolefin sheath  15  along substantially all of its length and a strain relief sleeve  17  covering a portion of the coil which extends from the handle  12 . The control wire  18  is preferably flexible but longitudinally inelastic and is ideally formed from 304 Steel and provided with and outer diameter of approximately 0.018 inch. The proximal handle  12  includes a central shaft  20  and a displaceable spool  22 . The proximal end of the shaft  20  is provided with a thumb ring  24  and a longitudinal bore  26  is provided at the distal end of the shaft  20 . A longitudinal slot  28  extends from the proximal end of bore  26  to a point distal of the thumb ring  24 . The displaceable spool  22  is provided with a cross member  30  which passes through the slot  28  in the central shaft  20 . The cross member  30  is provided with a central through hole  32  and a radially engaging set screw  34 . A short bore  36  and a radially engaging set screw  38  are provided in the shaft  20  distal of the thumb ring  24  with the bore  36  communicating with the longitudinal slot  28 . The proximal end of the coil  16  extends into the central through hole  32  in the cross member  30  and is fixed there by the set screw  34 . The proximal end of the control wire  18 , passes through slot  28 , is inserted into the short bore  36 , and held there by the set screw  38 . From the foregoing, those skilled in the art will appreciate that relative movement of the shaft  20  and spool  22  results in movement of the control wire  18  relative to the coil  16 . Such action results in actuation of the end effector  14  as described in detail below. 
     Turning now to FIGS. 2 through 4, according to a first embodiment of the invention, the end effector  14  includes a cylinder  40  having a distal edge  42  and a jaw assembly  44 . The jaw assembly  44  includes a pair of end effectors  44   a,    44   b,  a screw  102 , and a washer or retaining sleeve  104 . Each end effector  44   a,    44   b  includes a jaw cup  46   a,    46   b  preferably having a rim  48   a,    48   b  with radially arranged teeth, and a resilient, preferably narrow, arm  50   a,    50   b  which extends proximally from the jaw cup  46   a,    46   b.  The proximal end  51   a,    51   b  of the narrow arm  50   a,    50   b  preferably includes a sharply descending angled portion  52   a,    52   b.  The approximate center of the arm  50   a,    50   b  is bent at  53   a,    53   b  so that the arms diverge as seen in FIG.  2 . The arms  50   a,    50   b  are formed from super-elastic memory metal such as Nitinol (nickel-titanium alloy), and are biased apart from each other due to bends  53   a,    53   b,  thereby urging the jaw cups  46   a,    46   b  apart as seen in FIG.  2 . In addition, as the arms  50   a,    50   b  and the jaws  46   a,    46   b  are preferably integral with each other, the jaws are preferably formed from a super-elastic or shape memory metal. 
     The proximal end  51   a,    51   b  of each arm  50   a,    50   b  is coupled to the distal end  16   a  of the coil  16  by crimping/locking with a hollow threaded screw  102  and a washer  104 . The threaded screw  102  is substantially cylindrical, and generally includes a head portion  106 , a threaded portion  108 , and a cylindrical throughbore  110  along its central axis. The throughbore  110  is dimensioned to receive and allow movement of the control wire  18 . The distal end  112  of the head portion  106  has a diameter substantially equal to that of the outer diameter of the coil  16 , and is provided with two opposing grooves  114   a,    114   b  on the outer perimeter of the distal end  112  of the head portion  106 . Grooves  114   a,    114   b  are dimensioned to receive the angled portion  52   a,    52   b  at the proximal end  51   a,    51   b  of each of the narrow arms  50   a,    50   b.  The proximal end of the head portion  106  is frustroconical with a smaller diameter at the threaded portion  108 . The threaded portion  108  has a diameter slightly larger than the inner diameter of the coil  16  and the proximal end of the threaded portion  108  includes threads  124  for lockingly engaging the interior of the distal end  16   a  of the coil  16 . 
     The washer  104  is substantially cylindrical, and generally includes a throughbore  126 . The distal portion of the throughbore  126  is frustroconical. It will be appreciated that the throughbore  126  of the washer  104  has substantially the same configuration as the proximal end of the head portion  106  of the screw  102 . It will therefore be understood that the throughbore  126  of the washer  104  is dimensioned for engaging the proximal end of the head portion  106  of the screw  102  and distal end  16   a  of the coil  16  with the stepped  52   a,    52   b  proximal ends  51   a,    51   b  of the narrow arms  50   a,    50   b  positioned in the grooves  114   a-b  of the threaded screw  102  when the screw is threaded into the interior of the distal end  16   a  of the coil  16 . The stepped  52   a,    52   b  proximal ends  51   a,    51   b  of the narrow arms  50   a,    50   b  are thus fastened between the washer  104  and the threaded screw  102 . 
     As shown in FIGS. 2 through 4, the control wire  18  is provided with a bent end  18   a  which is welded to a hole  45  in the side of the cylinder  40 . However, as described in detail in the related applications, other methods of coupling the control wire to the cylinder are possible. The cylinder  40  is slidably mounted over the cylindrical washer  104  and head portion  106  of the threaded screw  102 , and is axially movable over the resilient arms  50   a,    50   b,  thereby bending the arms and closing the jaws  46   a,    46   b  as shown in FIG.  4 . As the resilient arms  50   a,    50   b  are made of superelastic metal, they will immediately return to their original open position (FIG. 2) once the cylinder  40  is retracted. 
     As seen best in FIGS. 3 and 4, each jaw  46   a,    46   b  has a widest part or apex  47   a,    47   b  which is denoted by the line  47   a  in FIG.  3 . When the distal end  42  of the cylinder  40  reaches the apex  47   a,    47   b  of the jaws (or some definite point proximal of the apex), the jaws are completely closed. 
     From the foregoing description and with reference to FIGS. 1 through 4, those skilled in the art will appreciate that when the spool  22  and the shaft  20  are axially displaced relative to each other, the cylindrical sleeve  40  and the end effectors  44   a,    44   b  are similarly axially displaced relative to each other, from the positions shown in FIG. 2 to the positions shown in FIG.  5  and vice versa. When the spool  22  and shaft  20  are in the approximate position shown in FIG. 1, the cylindrical sleeve  40  and the end effectors  44   a,    44   b  will be in the approximate position shown in FIG. 2; i.e., with the jaws open. Thus, when the spool  22  is moved towards the thumb ring  24 , or vice-versa, the cylindrical sleeve  40  and the end effectors  44   a,    44   b  will be brought into the approximate position shown in FIG. 4; i.e., with the jaws closed. Moreover, it will also be appreciated that it is preferable to move the thumb ring  24  relative to the spool  22 , rather than vice versa since that will move the cylindrical sleeve  40  relative to the end effectors  44   a,    44   b  rather than vice versa. This is desirable so that the end effectors are not moved away from a tissue sample while the jaws are being closed. 
     According to the first embodiment of the invention, a crimped stopping band or welded stopping sleeve  19  is provided on the control wire  18 . The stopping band  19  has an outer diameter which is larger than the diameter of the throughbore  110  of the screw  102 . The stopping band  19  is specifically located on the control wire  18  so that the distance between the stopping band  19  and the screw  102  is substantially equal to the distance between the distal edge  42  of the cylinder  40  and the apices  47   a,    47   b  (or desired closing point) of the jaws  46   a,    46   b.  Therefore, when the jaws are moved to the closed position as shown in FIG. 4, the control wire  18  and the coil  16  are stopped from further displacement by the stopping band  19  and the screw  102 . The hard stop provided by the stopping band  19  abutting the screw  102  prevents the cylinder  40  from pushing harder on the end effectors. 
     Turning now to FIGS. 5 and 6, and with reference to FIG. 1, a second embodiment of a bioptome  100  according to the invention may utilize substantially the same proximal handle  12  as the bioptome  10  described above. The difference in this second embodiment lies primarily in the end effector assembly  114  and in how that assembly is coupled to a coil  116  and control wire  118 . The coil  116  may be substantially the same as the coil  16  described above, having a sheath  115 , and the control wire  118  may be substantially the same as the control wire  18  described above, having a bent end  118   a.  According to this second embodiment of the invention, the end effector  114  includes a cylinder  140  having a distal edge  142 , and a jaw assembly  144 . The jaw assembly  144  includes a pair of opposed jaw cups  146   a,    146   b  each preferably having a plurality of sharp teeth  148   a,    148   b.  A resilient, preferably narrow, arm l 50   a,    150   b  extends proximally from each jaw cup  146   a,    146   b.  A cylindrical base member  152  joins the proximal ends of the arms  150   a,    150   b.  The narrow resilient arms  150   a,    150   b  are biased apart from each other, thereby urging the jaw cups  146   a,    146   b  apart. The cylindrical base member  152  of the jaw assembly  144  is coupled to the distal end  118   a  of the control wire  118  by providing the base member  152  with a lateral hole  153  and providing the distal end  118   a  of the control wire with a substantially right angle bend. The distal end  118   a  of the control wire  118  is soldered or otherwise attached in the hole  153  in the base member  152 . The cylinder  140  is coupled to the distal end  116   a  of the coil  116  by crimping and/or soldering. 
     From the foregoing description, and with reference to FIGS. 1,  5 , and  6 , those skilled in the art will appreciate that when the spool and the shaft ( 22 ,  20  in FIG. 1) are axially displaced relative to each other, the cylindrical sleeve  140  and the jaw assembly  144  are similarly axially displaced relative to each other, from the positions shown in FIG. 5 to the positions shown in FIG.  6  and vice versa. It will also be appreciated that when the spool and shaft are in the approximate position shown in FIG. 1, the cylinder  140  and the jaw assembly  144  will be in the approximate position shown in FIG. 5; i.e., with the jaws open. Thus, those skilled in the art will further appreciate that when the spool is moved towards the thumb ring ( 24  in FIG.  1 ), or vice versa, the cylinder  140  and the jaw assembly  144  will be brought into the approximate position shown in FIG. 6 by movement of the jaw assembly into the cylinder, thereby closing the jaws. 
     In accord with the second embodiment of the invention, the cylinder  140  is provided with an annular stopping crimp  141  at a point distal of the distal end  116   a  of the coil  116 , but proximal of the distal edge  142  of the cylinder  140 . The distance between the stopping crimp  141  and the proximal end  152   a  of the jaw assembly is preferably approximately equal to the distance between the distal edge  142  of the cylinder  140  and the points  147   a,    147   b  on the jaw cups where the distal edge of the cylinder lies when the jaws are closed. It will therefore be appreciated that when the jaws are brought into the closed position as shown in FIG. 6, the base member  152  of the jaw assembly  144  abuts the stopping crimp  141  in the cylinder  140  as soon as the jaws are closed. This prevents further movement of the cylinder  140  and jaw assembly  144  relative to each other and thereby limits the cutting force applied to the jaws. 
     Referring now to FIGS. 7 and 8, according to a third embodiment of the invention, the end effector  214  includes a cylinder  240  having a distal edge  242  and a jaw assembly  244 . The jaw assembly  244  includes a pair of jaws  244   a,    244   b,  a screw  302 , and a washer or retaining sleeve  304 . The jaw assembly is substantially the same the jaw assembly  44  described above with reference to FIGS. 2-4 and is coupled to the distal end of the coil  216  in substantially the same manner as described above. According to this embodiment, a portion  216   a  of the coil  216  which is proximally adjacent to the washer  304  is ground to a reduced external diameter. The length of the reduced diameter portion  216   a  is preferably approximately equal to the distance between the distal edge  242  of the cylinder  240  (when the jaws are open) and the points  247   a,    247   b  on the jaw cups where the distal edge of the cylinder lies when the jaws are closed. In addition, the proximal end of the cylinder  240  is provided with a radially inward directed flange  243  which defines a proximal opening having a diameter slightly larger than the reduced diameter of the ground portion  216   a.  The cylinder  240  is coupled to the control wire  218  in substantially the same manner as the cylinder  40  of the first embodiment is coupled to the control wire  18 , described above with reference to FIGS. 1-4. It will therefore be appreciated that when the jaws are brought into the closed position as shown in FIG. 8, the flange  243  of the cylinder  240  abuts the washer  304  as soon as the jaws are closed. This prevents further movement of the cylinder  240  and jaw assembly  244  relative to each other and thereby limits the cutting force applied to the jaws. 
     Referring now to FIGS. 9 and 10, according to a fourth embodiment of the invention, the end effector  314  includes a cylinder  340  having a distal edge  342  and a jaw assembly  344 . The cylinder  340  is substantially the same as the cylinder  40  described above and is coupled to the control wire  318  in substantially the same manner as the cylinder  40  is coupled to the wire  18 . The jaw assembly  344  includes a pair of jaws  344   a,    344   b,  a screw  402 , and a washer or retaining sleeve  404 . The jaw assembly is similar to the jaw assembly  44  described above with reference to FIGS. 2-4 and is coupled to the distal end of the coil  316  in substantially the same manner as described above. According to this fourth embodiment, each jaw  344   a,    344   b  is provided with a outer surface step  345   a,    345   b  which is located approximately at the points on the jaw cups where the distal edge of the cylinder lies when the jaws are closed. It will therefore be appreciated that when the jaws are brought into the closed position as shown in FIG. 10, the distal edge  342  of the cylinder  340  abuts the steps  345   a,    345   b  on the outer surfaces of the jaws  344   a,    344   b.  This prevents further movement of the cylinder  340  and jaw assembly  344  relative to each other and thereby limits the cutting force applied to the jaws. 
     There have been described and illustrated herein several embodiments of an endoscopic multiple sample bioptome. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular configurations of the cutting edges of the jaws, it will be appreciated that other types of cutting edges could be utilized. In particular, the cutting edges may have teeth or a toothless sharp edge, or a combination of both. The teeth may be radially arranged or arranged in another manner. In addition, while the jaws have been shown as coupled to the coil with a screw and washer in several embodiments, other coupling means could be provided. Moreover, while the cylinder has been described as having a stopping crimp in the second embodiment, other types of radial occlusions may be used to limit movement of the jaw assembly and the cylinder relative to each other. In fact, if the base member of the jaw assembly and/or the cylinder is properly dimensioned and located, the coil itself can be used as the stopping device. It will therefore be appreciated that in the third embodiment of the invention, the proximal flange on the cylinder could be replaced with a stopping crimp. Also, it will be appreciated that while the invention was described as advantageously permitting the obtaining of multiple biopsies without removal from the surgical site, the apparatus of the invention, if desired, could still be used for obtaining single biopsies at a time. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.