Abstract:
The invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a resecting device having a cutter near its distal end for resecting and containing a tissue sample and a sheath exterior to the resecting device and sized to be present within the body with the resecting device. The sheath includes an electrode element electrically isolated from the resecting device and disposed on the sheath&#39;s outer surface for cauterizing tissue. The electrode element may reside on the outer sheath, the distal end or both the outer sheath and the distal end of the assembly. The resecting device and the sheath cooperate to permit sequential resecting of a tissue sample from a resecting site and cauterizing of the site with the cutter sufficiently spaced from the electrode element to avoid heat damage to the tissue sample.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of Ser. No. 09/361,532 which was filed on Jul. 27, 1999 entitled Biopsy Sampler and is assigned to the same assignee as the present invention. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to biopsy sampling.  
           [0004]    2. Description of Related Art  
           [0005]    There are many biopsy procedures in which tissue samples are taken for later histology. In “cold” biopsy procedures, surgical forceps are inserted within, for example, an endoscope, and are used to resect (i.e., cut) a tissue sample from, for instance, the biliary tree or colon. The forceps, and, hence, the tissue sample, are then removed from the patient through the endoscope.  
           [0006]    Extensive bleeding can occur as a result of cold resecting, which can lead to dangerous blood loss levels. Hence, after the tissue sample is removed, another device can be inserted into the patient through the endoscope to stop the bleeding. These devices include tamponade devices which apply pressure to the bleeding site to stop the bleeding, devices which apply alcohol to the bleeding site to stop the bleeding, and electro-cautery devices which apply radio frequency (RF) energy to one or more electrodes (monopolar or bipolar) in contact with the bleeding site to cauterize the tissue and stop the bleeding. Following resecting, time is required to remove the forceps and tissue sample and insert a device to stop the bleeding. During this time, the resecting site continues to bleed.  
           [0007]    Alternatively, a “hot” biopsy procedure is performed using surgical forceps in which the jaws are electrodes (bipolar or monopolar). After the tissue sample is resected, the forceps are brought in contact with tissue remaining at the resecting site and RF energy is applied to the forceps to cause current to flow (i.e., cauterization) through the resecting site tissue to coagulate the tissue and stop the bleeding. Coagulation of the tissue may also kill cancerous or precancerous tissue at the resecting site. Often, RF energy is applied to the forceps during resecting to help cut the tissue sample as well.  
           [0008]    The tissue sample is again removed from the patient through the endoscope for histology. The tissue sample, however, may be inadvertently cauterized when the resecting site is cauterized rendering the tissue sample unusable for histology, e.g., the question of cell malignancy cannot be answered. The forceps may be lined with insulating material to electrically isolate the tissue sample from the forceps. However, heat generated when the resecting site tissue is cauterized may coagulate the tissue sample within the forceps, again, rendering the tissue sample unusable for histology.  
           [0009]    U.S. Pat. No. 5,336,222 to Durgin, Jr. et al., issued on Aug. 9, 1994 entitled Integrated Catheter For Diverse In Situ Tissue Therapy; U.S. Pat. No. 5,403,311 to Abele et al., issued Apr. 4, 1995 entitled Electro-Coagulation And Ablation And Other Electrotherapeutic Treatments Of Body Tissue, and U.S. Pat. No. 5,522,815, issued Jun. 4, 1996 to Durgin, Jr., et al. and entitled Integrated Catheter For Diverse In Situ Tissue Therapy are assigned to the assignee of the present application and are hereby incorporated herein in their entirety by reference.  
         SUMMARY  
         [0010]    In one aspect, the invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a resecting device having a cutter near its distal end for resecting and containing a tissue sample and a sheath exterior to the resecting device and sized to be present within the body with the resecting device. The sheath includes an electrode element electrically isolated from the resecting device and disposed on the sheath&#39;s outer surface for cauterizing tissue. The resecting device and the sheath cooperate to permit sequential resecting of a tissue sample from a resecting site and cauterizing of the site with the cutter sufficiently spaced from the electrode element to avoid heat damage to the tissue sample.  
           [0011]    Implementations of the invention may include the following features. The sheath may include a lumen sized to slidably receive the resecting device or the sheath and the resecting device may be constructed as a unitary device where the cutter extends distally of the termination of the sheath and the electrode is spaced proximally of the cutter. The cutter may include forceps. The electrode element may be a monopolar electrode or a pair of bipolar electrodes, and, in both cases, the electrodes may be cylindrical. The bipolar electrodes may also be “C” shaped. Additionally, the sheath may be precurved or the sheath may be deflectable through the use of a tension wire having a distal end fixed toward the distal end of the sheath such that pulling on a proximal end of the tension wire causes a distal portion of the sheath to bend. The sheath may include a lumen disposed in its sidewall for receiving an electrical connection to the electrode element, and the same lumen can be used for receiving the tension wire. The assembly can be sized to pass through an endoscope.  
           [0012]    In another aspect, the invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a resecting device including forceps near its distal end for resecting and containing a tissue sample, and a sheath exterior to the resecting device and sized to be present within the body with the resecting device. The sheath includes a lumen sized to slidably receive the resecting device and an electrode element electrically isolated from the resecting device and disposed on the sheath&#39;s outer surface for cauterizing tissue. The resecting device and the sheath are cooperatively constructed to permit sequential resecting of a tissue sample from a resecting site and cauterizing of the site with the forceps spaced from the electrode element sufficiently to avoid heat damage to the sample.  
           [0013]    In another aspect, the invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a resecting device including forceps near its distal end for resecting and containing a tissue sample, and a sheath exterior to the resecting device and sized to be present within the body with the resecting device. The sheath and the resecting device are constructed as a unitary device and the forceps extend distally of the termination of the sheath. The sheath includes an electrode element electrically isolated from the resecting device, spaced proximally to the forceps, and disposed on the sheath&#39;s outer surface for cauterizing tissue. The resecting device and the sheath are cooperatively constructed to permit sequential resecting of a tissue sample from a resecting site and cauterizing of the site with the forceps spaced from the electrode element sufficiently to avoid heat damage to the sample.  
           [0014]    In another aspect, the invention features a method for taking a biopsy sample with an assembly from a site within the body of a patient. The assembly includes a resecting device having a cutter near its distal end for resecting and containing a tissue sample and a sheath exterior to the resecting device and sized to be present within the body with the resecting device. The sheath includes an electrode element electrically isolated from the resecting device and disposed on the sheath&#39;s outer surface for cauterizing tissue. The resecting device and the sheath cooperate to permit sequential resecting of a tissue sample from a resecting site and cauterizing of the site with the cutter sufficiently spaced from the electrode element to avoid heat damage to the tissue sample. The method further includes resecting a tissue sample from a resecting site with the resecting device and containing the tissue sample with the cutter. Additionally, the electrode element is located at the resecting site with the cutter containing the sample spaced from the electrode element, and the site is cauterized by application of power to the electrode element.  
           [0015]    Implementations of the invention may include the following features. The sheath may include a lumen sized to slidably receive the resecting device, and the method may further include inserting the resecting device within the lumen of the sheath, extending the resecting device from a distal end of the sheath to position the resecting device at a resecting site, and withdrawing the resecting device within the lumen a distance away from the distal end of the sheath. The method may include extending the cutter from the sheath to space the cutter from the electrode. The method may also include withdrawing the resecting device completely from the sheath, removing the tissue sample from the resecting device, reinserting the resecting device within the lumen of the sheath, extending the resecting device from the distal end of the sheath to position the resecting device at a new resecting site, resecting a tissue sample from the new resecting site with the resecting device, containing the tissue sample with the cutter, withdrawing the resecting device within the lumen a distance away from the electrode element, positioning electrode element at new resecting site, and cauterizing the new resecting site by application of power to the electrode element. The method may also include inserting an endoscope within the body and inserting the sheath within the endoscope. Moreover, the sheath and the resecting device may be constructed as a unitary device where the cutter extends distally of the termination of the sheath and the electrode is spaced proximally of the cutter, and the method may further include positioning the resecting device and the sheath along a treatment path, positioning the resecting device at a resecting site, resecting a tissue sample from the resecting site with the resecting device, containing the tissue sample with the cutter, positioning the electrodes at the resecting site, and cauterizing the site by application of power to the electrode element.  
           [0016]    Embodiments may include one or more of the following advantages: For example, polyps and other aberrant tissue can be resected and the resection site can be cauterized without heat-damaging the sample or removing the sampling device from the patient&#39;s body before cauterizing. For example, in embodiments, the resected tissue is slid axially a predetermined short distance away from the cauterizing electrodes so that heat from the electrodes does not affect the sample integrity. The bleeding of the resecting site is quickly electro-cauterized. The resection can be carried out using a cauterizing sheath having electro-cautery electrodes disposed on a distal end of the sheath and having surgical forceps slidably disposed within a lumen in the sheath. The surgical forceps are used to resect the tissue sample and axially remove the sample from the resecting site, while the electro-cautery electrodes are used to cauterize the resecting site to stop bleeding. In other embodiments, the distance between the electrodes and the forceps is fitted at a preselected spacing sufficient to avoid heat damage when the assembly is maneuvered to position the electrodes at the resection site for cauterization. The need for additional tissue removal, additional biopsy procedures, complications from blood loss, time in surgery, and patient trauma may all be reduced. The instrument can be constructed for use with a variety of existing surgical devices and can be easily manufactured.  
           [0017]    In each of these embodiments of the invention the electrode element may reside on the outer sheath of the assembly, the distal end of the assembly or both. Various configurations of electrode elements are possible including parallel horizontal configuration or an alternating spiral configuration. In addition, electrode elements may include a three dimensional configuration to aid in cauterization.  
           [0018]    Additional advantages and features are apparent from the following.  
         DETAILED DESCRIPTION 
     
    
    
       [0019]    [0019]FIG. 1 a  is an exploded side view of a biopsy assembly including a resecting device and a cauterizing sheath;  
         [0020]    [0020]FIG. 1 b  is view similar to FIG. 1 a  with the resecting device positioned within the cauterizing sheath;  
         [0021]    [0021]FIG. 2 is an enlarged perspective view of a distal portion of the biopsy assembly of FIG. 1 b , with a part of the sheath cut-away;  
         [0022]    [0022]FIG. 3 is an enlarged perspective view of a distal portion of the biopsy assembly of FIG. 1 b  with surgical forceps of the resecting device axially extended from the cauterizing sheath;  
         [0023]    [0023]FIGS. 4 a - 4   c  and  4   f  are side views of the distal portion of the biopsy assembly of FIG. 1 b  disposed within an endoscope and in use within a colon;  
         [0024]    [0024]FIGS. 4 d  and  4   e  are end views of the distal end of the biopsy assembly of FIG. 1 b  disposed within an endoscope and in use within a colon;  
         [0025]    [0025]FIG. 5 is a side view of another embodiment of an assembly;  
         [0026]    [0026]FIGS. 6 and 7 a  are side views of other embodiments of an assembly;  
         [0027]    [0027]FIG. 7 b  is an end view of the assembly of FIG. 7 a ;  
         [0028]    [0028]FIGS. 8 a  and  8   b  are side views illustrating structure and use of another embodiment of an assembly, with a portion of the assembly of FIG. 8 a  cut-away;  
         [0029]    [0029]FIGS. 9 a , and  9   b - 9   c  are side and two end views illustrating an embodiment of the spiraling electrodes of the present invention;  
         [0030]    [0030]FIGS. 10 a  and  10   b  are side and end views illustrating another embodiment of the spiraling electrodes of the present invention;  
         [0031]    [0031]FIG. 10 c  is a side view illustrating a configuration for connecting the spiraling electrodes of FIG. 10 a  cutaway;  
         [0032]    [0032]FIG. 10 d  is a axiomatic view of the embodiment of FIGS. 10 a ,  10   b  and  10   c;    
         [0033]    [0033]FIG. 10 e  illustrates how the parallel electrodes of the embodiment displayed in FIGS. 10 a  and  10   b  may be situated around the distal end of the sheath to allow bipolar contacts;  
         [0034]    [0034]FIGS. 11 a , and  11   b  are side and end views illustrating another embodiment of the spiraling electrodes of the present invention;  
         [0035]    [0035]FIGS. 12 a , and  12   b  are a side view and an end view illustrating another embodiment of the spiraling electrodes of the present invention;  
         [0036]    [0036]FIGS. 13 a , and  13   b  are side and end views illustrating another embodiment of the spiraling electrodes of the present invention;  
         [0037]    FIGS.  14 - 17  are side views illustrating various configurations of the electrodes; and  
         [0038]    [0038]FIGS. 18 a  and  18   b  are two end views of another embodiment of the present invention. 
     
    
     DESCRIPTION OF ILLUSTRATED EMBODIMENTS  
       [0039]    Referring to FIGS. 1 a ,  1   b ,  2 , and  3 , a biopsy assembly  10  includes a cauterizing sheath  12  and a resecting device  14 . Sheath  12  includes a working lumen  16  extending from a proximal end  18  to a distal end  20  defined by an inner lumen wall  17  and sized to receive resecting device  14 . The sheath also includes a pair of bipolar electrodes  22   a ,  22   b  mounted on an outer sheath surface  13  near distal end  20 . Sheath  12  also includes an electrical connector  24 , for connection to a radio frequency (RF) generator (not shown), and a lumen  26 , extending between outer surface  13  and inner surface  17  of sheath  12  from electrical connector  24  to electrodes  22   a ,  22   b . Two wires  28  are disposed within lumen  26 , and each wire  28  electrically connects one of the electrodes  22   a  and  22   b  to electrical connector  24 . Wires  28  are each coated with a layer of electrical insulation to prevent electrical contact between the wires.  
         [0040]    Resecting device  14  is slidably positioned within working lumen  16  and includes a cutter, for example, forceps  30  (e.g., cup-shaped jaws,  30   a ,  30   b ), a handle  32 , and a jacket  33 . Handle  32  includes a positioning ring  35  and a forceps grip  38 . Positioning ring  35  is mechanically coupled to forceps  30  through wires  37 , and forceps grip  38  is mechanically coupled to forceps  30  through jacket  33 . Positioning ring  35  or jacket  33  is pulled (arrow  34 , FIG. 2) to axially withdraw forceps  30  within working lumen  16  toward proximal end  18  of sheath  12  and pushed (arrow  36 , FIG. 3) to axially extend forceps  30  from working lumen  24  at distal end  20  of sheath  12 . Once extended from working lumen  24 , forceps grip  38  is pushed (arrow  36 ) to open (dashed lines  42   a ,  42   b , FIGS. 1 b ,  3 ) and pulled (arrow  41 ) to close (solid lines  44   a ,  44   b , FIGS. 1 b ,  2 ,  3 ) jaws  30   a  and  30   b  of forceps  30 . Because electrodes  22   a  and  22   b  are disposed on outer sheath surface  13  and wires  28  are positioned within electrical lumen  26 , forceps  30  are electrically isolated from electrodes  22   a  and  22   b.    
         [0041]    Handle  32  is used to extend forceps  30  from working lumen  16  beyond distal end  20  of sheath  12  and is used to open jaws  30   a  and  30   b  to surround a tissue sample, e.g., a polyp, and close jaws  30   a  and  30   b  to resect and contain the polyp. Handle  32  is then used to withdraw forceps  30  within working lumen  16  to spatially remove forceps  30 , and, hence, the tissue sample, from electrodes  22   a ,  22   b  on distal end  20  of sheath  12 . Proximal end  18  of sheath  12  is then pushed to locate electrodes  22   a ,  22   b  adjacent tissue remaining at the resecting site and RF energy is applied to electrodes  22   a ,  22   b , through electrical connector  24  and wires  28 , to electro-cauterize the tissue remaining at the resecting site.  
         [0042]    In a particular embodiment, sheath  12  is teflon, which has a low coefficient of friction allowing resection assembly  12 , including stainless steel forceps  30 , stainless steel coil jacket  33 , and stainless steel wires  27  to easily slide within working lumen  16  and a relatively high melting point to prevent sheath  12  from melting when tissue adjacent to electrodes  22   a ,  22   b  is heated during cauterization. Sheath  12  has a wall thickness of approximately 0.15 mm and is about 150 cm in length. In one embodiment, the outer diameter of sheath  12  is about 2.6 mm, the diameter of working lumen  16  is approximately 2.3 mm, and the closed diameter of the jaws of forceps  30  is approximately 2.2 mm which provides about 0.1 mm of clearance between forceps  30  and inner sheath surface  17  when the jaws of forceps  30  are closed and withdrawn within working lumen  16 . Such an assembly can be passed through a lumen (i.e., lumen  54 , FIG. 4 a ) in an endoscope (i.e., endoscope  50 , FIG. 4 a ) having a diameter of about 2.7 mm. Electrodes  22   a  and  22   b  are cylindrical electrodes having a width, W 1 , of approximately 2.0 mm and are separated along outer sheath surface  13  by a distance, d 1 , of about 4.0 mm. After forceps  30  have resected and are containing a tissue sample, forceps  30  are withdrawn (arrow  34 , FIG. 2) within working lumen  16  a distance d 2  of approximately 2 inches or more from electrode  22   b  to prevent the tissue sample from being damaged by cauterization or by heat generated during tissue coagulation.  
         [0043]    In another embodiment, the outer diameter of shaft  12  is again 2.6 mm and the diameter of working lumen  16  is again approximately 2.3 mm, however, the closed diameter of the jaws of forceps  30  is approximately 1.8 mm. In yet another embodiment, the outer diameter of shaft  12  is about 3.7 mm, the diameter of working lumen  16  is approximately 3.4 mm and the closed diameter of the jaws of forceps  30  is approximately 3.3 mm.  
         [0044]    1. Use  
         [0045]    Referring to FIGS. 4 a - 4   f , the operation of assembly  10  will be described with regard to the removal of a polyp  46  from a patient&#39;s colon  48 . The patient is prepared by inserting an endoscope  50  to the region of treatment. The physician, with optical lens  52 , inspects the region. Through a lumen  54  in endoscope  50 , the region is flushed, e.g., with saline. Outside the body, the resecting device is inserted within the sheath such that the forceps are near but do not extend from the distal end of the sheath.  
         [0046]    Referring particularly to FIG. 4 a , sheath  12  and resecting device  14  are then inserted together in lumen  54  of endoscope  50 . Resecting device  14  provides additional strength to sheath  12  to prevent sheath  12  from buckling as it is inserted within endoscope  50 . Alternatively, biopsy assembly  10  can be inserted within endoscope  50  before endoscope  50  is inserted within the patient to save time in surgery.  
         [0047]    Referring to FIG. 4 b , once positioned, resecting device  14 , including forceps  30 , is extended (arrow  56 ) beyond distal end  20  of sheath  12 , and, jaws  30   a ,  30   b  are opened (arrow  58 , FIGS. 4 c  and  4   d ). As resecting device  14  is further extended, jaws  30   a  and  30   b  surround polyp  46 . The jaws are closed (FIG. 4 e ) causing the edges of jaws  30   a  and  30   b  to resect polyp  46  or a portion of polyp  46 .  
         [0048]    Referring to FIG. 4 f , resecting device  14 , including forceps  30  containing polyp  46 , is then withdrawn (arrow  60 ) within working lumen  16  of sheath  12  approximately 2 inches or more proximal to electrode  22   b . Sheath  12  is pushed forward (arrow  62 ) and endoscope  50  is pushed up (arrow  64 ) to bring electrodes  22   a ,  22   b  in contact with resecting site  66 . RF energy is then applied to electrodes  22   a ,  22   b  through wires  28  (FIG. 1 b ) and electrical connector  24  to cause current to pass through the resecting site tissue between electrodes  22   a ,  22   b . The current heats the resecting site to approximately 60-100 degree C. which is sufficient to coagulate the resecting site tissue. The distance between forceps  30  and electrodes  22   a ,  22   b  is sufficient to prevent current from traveling through polyp  46  within forceps  30  and sufficient to prevent the heat in the resecting site from coagulating polyp  46  within forceps  30 . An irrigant flush, e.g., saline, through working channel  16  can also be used to cool forceps  30  to provide additional protection against coagulation of polyp  46  within forceps  30 . As a result, an undamaged tissue sample is taken and the resecting site is quickly cauterized to prevent damaging blood loss.  
         [0049]    Endoscope  50 , sheath  12 , and resecting device  14  may then be removed from the patient and polyp  46  recovered from forceps  30  for histology. Alternatively, only resecting device  14  is removed, through sheath  12  and endoscope  50 , from the patient so that polyp  46  can be recovered for histology, and resecting device  14  is then reinserted within sheath  12  and endoscope  50  for removal of another tissue sample.  
         [0050]    2. Other Embodiments  
         [0051]    A single cylindrical monopolar electrode can be disposed on the outer sheath surface at the distal end of the sheath. With a monopolar electrode, the patient is placed on a grounding plate, and when RF energy is applied to the electrode, current travels between the electrode and the grounding plate. The current is concentrated in tissue adjacent to the electrode and causes sufficient heat to coagulate the adjacent tissue.  
         [0052]    Referring to FIG. 5, forceps  70  can be provided having one cup-shaped jaw  72  and one flat jaw  74 , where the flat jaw  74  is sharp along a forward edge  76  and is used to resect tissue that is then caught and contained by cup-shaped jaw  72 . Forceps  70  or forceps  30  (FIG. 1 a ) can also include a needle (not shown) to assist in resecting tissue samples.  
         [0053]    Referring to FIG. 6, a deflectable sheath  80  includes a resecting assembly  82  sidably disposed within an cauterizing sheath  84 . Resecting assembly  82  is similar to resecting assembly  12  described above with respect to FIGS. 1 a  and  1   b , and sheath  84  is similar to sheath  12  described above, except that sheath  84  includes a tension wire  86  for bending distal end  20  of sheath  84 . A distal end  88  of tension wire  86  is fixed to sheath  84 . A portion  90  of tension wire  86  extends along an outer surface  92  of sheath  84  and a proximal portion  94  of tension wire  86  extends within electrical lumen  26  of sheath  84 . The electrical insulation coating each of the wires  28  prevents electrical contact between tension wire  86  and wires  28 .  
         [0054]    After positioning sheath  84  and extending resecting assembly  82  beyond a distal end of sheath  84 , the physician pulls a proximal end (not shown) of tension wire  86 . Because distal end  88  is fixed to sheath  84 , pulling on wire  86  causes sheath  84  (and flexible jacket  33 , FIG. 1 a ) to bend (arrow  96 ) and lifts (arrow  98 ) wire  86  off outer surface  92  of sheath  84 . Bending the distal end of sheath  84  allows the physician greater flexibility in removing tissue samples and cauterizing resecting site tissue. Alternatively, sheath  12  (FIGS. 1 a ,  1   b ) can be manufactured to be precurved.  
         [0055]    Referring to FIGS. 7 a  and  7   b , a biopsy assembly  100  includes a resecting device  102  including forceps  104  (having jaws  104   a  and  104   b ) slidably disposed within cauterizing sheath  106 . “C” shaped electrodes  108 ,  110  are disposed on an outer surface  107  and a distal end  112  of sheath  106  and are separated by elastic members  114   a ,  114   b . The closed diameter of the jaws of forceps  104  is, for example, 3.3 mm, which is larger than the diameter, for example, 3.0 mm, of a lumen (not shown) of sheath  106 . Hence, inserting a proximal end of resecting device  102  in distal end  112  of the lumen of sheath  106 , eventually pushed forceps  104  against distal end  112  and forces elastic members  114   a ,  114   b  to expand (arrow  116 ).  
         [0056]    Biopsy assembly  100  is then inserted within an endoscope and positioned within a patient. Once in position, resecting device  102  is extended (arrow  118 ) from distal end  112  of sheath  106  and elastic member  114  compresses leaving “C” shaped electrodes  108 ,  110  separated by a distance of approximately 0.2 mm. Forceps  104  are used to resect a tissue sample from a resecting site, and electrodes  108  and  110  are then brought in contact with the resecting site tissue. Before RF energy is applied to electrodes  108  and  110  to cauterize the resecting site tissue, resecting device  102  is further extended (arrow  118 ) a predetermined distance (e.g., 2 inches or more) away from distal end  112  of sheath  106 . Both sheath  106  and resecting device  102  are then removed together from the endoscope in order to retrieve the tissue sample.  
         [0057]    Cylindrical electrodes  22   a  and  22   b  (FIG. 1 a ) can be replaced with two “C” shaped electrodes disposed on distal end  20  of sheath  12  and separated by a fixed distance, e.g., 0.2 mm. With such an arrangement, forceps  30  can be pulled within sheath  12 , the distal end of the sheath can be pushed against a resecting site, for example, at a bend or elbow in a colon, and RF energy can be applied to the electrodes to cauterize the resecting site tissue.  
         [0058]    Referring to FIGS. 8 a  and  8   b , a biopsy assembly  120  is shown inserted within a lumen  122  of a deflectable endoscope  124  which is positioned within a colon  125  of a patient. Biopsy assembly  120  includes a resecting device  126  having forceps  128  disposed on a distal end  130  of a stainless steel coil  132 . A teflon shaft  134  is disposed on stainless steel coil  132 , and two cylindrical electrodes  136 ,  138  are disposed on an outer surface  140  of shaft  134 . Shaft  134  electrically isolates forceps  128  from electrodes  136 ,  138 . Shaft  134  is extended (arrow  142 , FIG. 8 a ) through endoscope lumen  122  and the jaws of forceps  128  are opened. Shaft  134  is then further extended to position the opened jaws of forceps  128  around polyp  144 . The jaws are then closed to resect polyp  144  and to contain polyp  144 . Shaft  134  is then further extended (arrow  146 , FIG. 8 b ) to bring electrodes  136  and  138  toward resecting site  148 . Deflectable endoscope  124  is then bent  150  to bring electrodes  136  and  138  in contact with resecting site  148 , and RF energy is applied to the electrodes to cauterize tissue at the resecting site  148 .  
         [0059]    Shaft  134  has a wall thickness of approximately 0.2 mm and is about 150 cm in length. The closed diameter of forceps  128  is about 2.2 mm. The outside diameter of stainless steel coil  132 , and, hence, the inside diameter of shaft  134 , is also about 2.2 mm. The outside diameter of shaft  134  is about 2.6 mm, and the diameter of endoscope lumen  122  is about 2.7 mm which provides about 0.1 mm of clearance between shaft  34  and the surface of lumen  122 . Electrode  136  is separated by a distance, d 3 , of approximately 2 inches from forceps  128  to prevent tissue samples contained in forceps  128  from being damaged by cauterization or by heat from coagulation. Electrodes  136  and  138  are cylindrical electrodes having a width, W 2 , of approximately 2.0 mm and are separated by a distance, d 4 , of about 4.0 mm.  
         [0060]    Alternate embodiments of the electrode configuration ( 22   a  &amp;  22   b  of FIG. 1 b , and  136  &amp;  138  of FIG. 8 b ) are also possible and included within the present invention. FIG. 9 a  shows alternating spiral electrodes  152 ,  154  which may be included on the other sheath surface  13 . The alternating spiral electrodes  152 ,  154  use RF energy from electrical connector  24  (FIG. 1 b ) to establish a catherization field between the electrodes of differing polarity. Wires  28  carry the RF energy from electrical connector  24  to spiral electrodes  152 ,  154 . FIGS. 9 b  and  9   c  show alternative electrode placement on the distal end  20  of the catheter sheath. FIG. 9 b  shows the inclusion of bipolar electrodes  156 ,  158  on distal end  20  of the sheath which is an extension of the spiral pattern included on the circumference of the sheath. Alternatively, FIG. 9 c  shows a pattern for electrodes  160 ,  162  in which distal end  20  of the sheath is divided into approximately two even areas for which electrodes of differing polarity are attached. One of ordinary skill in the art would understand that the spiral electrodes  152 ,  154  may extend long any length of outer sheath surface  13 .  
         [0061]    [0061]FIGS. 10 a  and  b  show an alternate arrangement of the electrode configuration on outer sheath surface  13  and distal end  20  of the sheath. In FIG. 10 a  the electrodes are applied to outer sheath surface  13  and include a tapered design which allows the spacing  164  between the electrodes to be reduced near the distal end  20 . By reducing the spacing  164  between the electrodes  166 ,  168  in FIG. 10 a , the electrode placement on the end of the sheath may also be modified as shown in FIG. 10 b . FIG. 10 b  includes multiple electrode pairs which have been placed on distal end  20 . The inclusion of the multiple electrode pairs allows cauterization with greater precision. Additionally, the addition of the electrode pairs on the end of the sheath allows the physician direct visualization as the end of the catheter is used to cauterize the bleeding tissue. The electrodes included on distal end  20  may be effected by either connecting to electrodes  166  and  168  or by partially running electrodes into the distal end  20  of the sheath body. FIG. 10 c  shows how branches can be used to interconnect individual electrodes at distal end  20 . FIG. 10 d  further illustrates the embodiment of FIGS. 10 a - c , but in axiometric view to more clearly exhibit a manner in which the electrodes may continuously extend around the distal end of the sheath and allow for bipolar point contacts. FIG. 10 d  illustrates the connections between the electrodes  168  and  166  on the sheath surface and the electrode pairs on the distal end  20 . FIG. 10 e  further illustrates the embodiment of FIGS. 10 a - 10   d . However, FIG. 10 e  illustrates how the parallel electrodes may be situated around the distal end of the sheath to allow for bipolar contacts. In FIG. 10 e , the electrodes are portrayed in a plane perpendicular to the axis of the sheath. The electrodes in FIG. 10 e  would be folded down to the inner and outer surfaces of the sheath to create the embodiments of FIGS. 10 a - 10   d.    
         [0062]    [0062]FIGS. 11 a  and  b  show another configuration for the electrodes  170 ,  172  on the sides of the sheath and on the sheath ends. FIG. 11 a  shows electrodes  170 ,  172  which run from the proximal end  18  of the catheter to distal end  20  in parallel. As seem in FIG. 11 b  these parallel electrodes are continued on the end of the sheath. Electrode pairs  170 ,  172  are insulated along portions of the sheath where cauterization is not desired and to protect tissue samples from inadvertent cauterization.  
         [0063]    [0063]FIGS. 12 a - 12   b  show another embodiment of the present invention in which the positive electrodes  174  are run along the outer sheath surface  13  and the negative electrodes  176  along the inner sheath surface  17 . In FIG. 12 a  positive electrodes  174  are positioned along outer sheath surface  13  and negative electrodes  176  are positioned along the inner sheath surface  17 . Electrodes  174  and  176  are electrically insulated from one another in areas in which cauterization is undesired. FIG. 12 b  shows distal end  20  of this embodiment. One of ordinary skill would understand that the position of the electrodes in this configuration can be switched so that positive electrodes  174  are on the inner sheath surface  17  and negative electrodes  176  are on the outer sheath surface  13 . FIG. 12 b  illustrates the electrode arrangement which would then be fitted to the distal end  20  of the sheath, by bending the electrodes around the inner and outer surfaces and adhering them to the sheath, or by alternative placement methods. While FIGS. 12 a  and  12   b  show the positive electrode on the outside of the sheath and the negative electrode on the inside, one of ordinary skill in the art would understand both elements can be on the outside, on the inside or divided between the inside and outside of the sheath.  
         [0064]    [0064]FIGS. 13 a - 13   b  show the number of electrodes on the distal end can be increased to more accurately cauterize a specific area. In this embodiment, each electrode is connected to electrical connector  24  by its own control wire  178 .  
         [0065]    FIGS.  14 - 17  show that the electrodes may be located at distal end  20  or on the outer sheath surface (sides)  20  of the sheath. Additionally, the electrodes may be shaped differently to affect cauterization to different areas. FIG. 14 shows electrodes  180  which are configured in the shape of raised circular areas or domes. FIG. 15 shows electrodes  182  which are configured as on one side of outer sheath surface  13 . FIG. 16 shows electrodes  184  which are configured as pyramids. FIG. 17 shows electrodes  186  which are located only on distal end  20 . One of ordinary skill in the art would understand that electrodes  180  and  184  may be located on distal end  20 , outer sheath surface  13 , or on both distal end  20  and outer sheath surface  13 . Additionally, one of ordinary skill in the art would understand that the different shapes described here are not limiting and that the invention encompasses electrodes of various shapes including, but not limited to, squares, circles, triangles, rectangles. The electrodes, as shown by FIGS. 14 and 16 may also have a three dimensional shape to improve the contact between the tissue and the electrode.  
         [0066]    [0066]FIGS. 18 a  and  18   b  illustrate a further embodiment of the invention. The positive  190  and negative  198  electrodes are brought to the distal end  20  of the sheath and wrapped parallel to each other in a plane perpendicular to the axis of the sheath. FIG. 18 a  illustrates the electrodes positioned on the distal end  20  of the sheath. FIG. 18 b  illustrates the same embodiment with the sheath removed for clarity of the illustration.  
         [0067]    One of ordinary skill would understand that the electrode element may be placed on any medical device which is deployed through an endoscope. Such medical devices may be snares, biopsy samplers, scissors, baskets, blades, needles, knives, tomes, injection snares or any other medical devices used to perform tissue-plasty or surgical manipulation of tissue after which cauterization is desired.  
         [0068]    Other embodiments are within the following claims.