Patent Publication Number: US-2007100335-A1

Title: Instrument for electrosurgical excision procedure for the uterine cervix

Description:
BACKGROUND OF INVENTION  
      1. Field of Invention This invention relates generally to an instrument for the surgical excision of tissues, more particularly to an instrument for electrosurgically excising a tissue specimen from the transformation zone of the uterine cervix.  
      2. Background of the Invention  
      Cancer of the uterine cervix, or cervical cancer, usually progresses slowly over an extended period from the first appearance of precancerous abnormalities. This gradual progression presents an opportunity for many patients to entirely avoid cervical cancer if they can benefit from preventive intervention. Even for those who do not, there is a good prognosis if the cancer is detected and treated early enough.  
      Before malignant cells are found, the tissues of the cervix go through changes in which abnormal cells begin to appear, initially on the epithelial tissue on the surface of the cervix. This precancerous condition is known as dysplasia or cervical intraepithelial neoplasia (CIN). CIN is a lesion of abnormal cells typically associated with the human papilloma virus (HPV). When HPV is contracted, it infects the cells of the transformation zone of the cervix where cells of the cervix actively divide and grow. As these cells grow and mature, they are pushed to the surface as new cells are produced and older, outside cells die and are shed. As the virus infects the cells and then becomes active, abnormal cells begin to be produced in the transformation zone and a lesion develops in the epithelial tissue at the surface of the cervix.  
      If left untreated, the cancer cells will start to grow and spread more deeply into the cervix and to surrounding areas. Approximately 30-50% of CIN conditions may progress to invasive cancer if not treated.  
      Removal of the lesion is an effective treatment for CIN. Although HPV remains once the CIN lesion is removed, the rate of reoccurrence is low since the removal of the transformation zone eliminates the tissue most susceptible to CIN.  
      Lesioned or dysplastic cells may be removed by cauterization, cryosurgery or laser surgery. A common surgical excision procedure employs loop electrosurgery, sometimes called the Loop Electrosurgical Excision Procedure or LEEP. LEEP uses a thin wire loop electrode connected to an electrosurgical generator that emits an electric current to cut away affected tissue. A low voltage and relatively high frequency electric current is emitted from the loop into the tissue cells in the immediate area of the loop wire. Consequently, the cells heat rapidly, generating steam that causes the cells to burst microscopically. Thus the tissue is divided as the wire moves through the tissue. The wire is typically swept across the projecting neck of the cervix, or ectocervix, thereby removing a thin annular slice of tissue. LEEP allows the physician to have the excised specimen analyzed by a pathology laboratory. This allows for more accurate assessment of the abnormal tissue, which will confirm either that the lesion has been completely removed with the biopsy sample, or if it has not, what further treatment may be necessary. The entire LEEP procedure usually takes less than 15 minutes and is generally very effective and well received.  
      One problem with LEEP is that the sample of tissue obtained may vary in amount and definition. LEEP is particularly prone to producing fragmented and burnt biopsy samples if it is necessary to make multiple passes of the loop. These problems with the samples reduce the accuracy of diagnosis. Another problem with LEEP is incomplete removal of the lesion when excising the transformation zone. This result can only worsen the patient&#39;s long-term prognosis and requires further procedures to remove the remaining abnormal cells. The converse risk is removal of too much tissue which may result in cervical stenosis or incompetent cervix and/or sterility. The primary cause of these problems is the inherent lack of stability of the loop, because it is generally on the distal end of a long handle for which there is no guiding support. This lack of stability is exacerbated because the electrode itself can move in relation to the handle under the influence of drag as the electrode passes through the cervical tissue. This compounds the difficulty of knowing exactly where the electrode is positioned at all times and adds to the difficulty of producing an accurate cut.  
      One solution to the problems associated with LEEP is the Fischer cone biopsy device as described in U.S. Pat. Nos. 5,554,159 and 5,403,310. The Fischer device includes an elongated insulated body member with an endocervical portion at the distal end, a contact portion at the proximal end, and a vaginal portion between the endocervical and contact portions. An insulated stop arm extends at right angles to the body member at the junction of the endocervical and vaginal portions. A wire electrode extends diagonally between the stop arm and the endocervical portion.  
      In use, the Fischer device is connected by means of the contact portion to an electrosurgical generator such as a blend cutting diathermy machine. The instrument is then inserted into the cervix through the vaginal canal. The vaginal canal is held open by a duckbill speculum as is well known in the art. The endocervical portion is inserted into the cervical canal to gain support for the distal end of the instrument, whereupon the wire electrode is energized through the contact portion and a conductor within the insulated body. When the energized wire contacts the cervical tissue at the ectocervix, a current passes through the wire into the patient to return through an electrode attached to a convenient part of the patient&#39;s body. This current heats the tissue cells adjacent the wire until they burst. The wire is then advanced through the cervix in a direction parallel to the longitudinal axis of the body member and the wire separates the cervical tissue. The endocervical portion extends farther into the cervical canal until the stop arm touches the ectocervix. When this position is reached, the instrument is turned one full revolution (360°) about the longitudinal axis of the body member to cut a conical tissue specimen from the transformation zone. The current is then turned off and the cut specimen is withdrawn with the instrument from the vaginal canal.  
      The endocervical portion extending into the cervical canal acts as a pivot about which the Fischer device is turned during the cutting operation. The pivot rotatably supports the distal end of the instrument. The arm abutting the ectocervix acts to determine the depth of cut during the cutting operation. The Fischer device has an improved accuracy over the loop electrode because the arm holds the diagonal electrode taut and straight throughout the procedure and because the electrode itself is as short as possible.  
      On occasion, the protruding end of the stop arm of the Fischer device, particularly a curved stop arm, has a tendency to engage or catch irregularities of the uterine cervix, thus interfering with the smooth rotation of the Fischer device about its axis. It is also desired by some physicians to be able to rotate the Fischer device about its axis in either a clockwise or counterclockwise direction without the stop arm catching on the uterine cervix.  
      Other related instruments are discussed in the following U.S. Pat. Nos. 6,730,085; 6,416,513; 6,309,388; 6,514,481; 6,344,026; 6,540,695; 6,659,105; 6,669,643; 6,676,658; 5,951,550; 5,676,663; and 5,616,469.  
     SUMMARY OF INVENTION  
      This invention relates generally to endocervical excision instruments which are specifically used for the excision of a tissue specimen from the transformation zone of a uterine cervix. Those instruments comprise various new embodiments of the Fischer device described above. In particular, the various configurations of the stop on the instrument facilitate rotation of the instrument in either direction without engaging or catching irregularities of the uterine cervix which could otherwise interfere with the smooth rotation of the instrument about its axis.  
      In one aspect, an instrument for excision of a tissue specimen from a transformation zone of a uterine cervix is disclosed. In one embodiment of this aspect, the instrument includes an elongated shaft having an endocervical portion disposed adjacent a first end, and a contact portion disposed adjacent a second end, in which the endocervical portion is structured to be inserted into a uterine cervix. A curved stop is disposed between the endocervical portion and the contact portion of the shaft in which the stop subtends an arc of greater than 180° in a plane disposed substantially perpendicularly of the shaft. At least one wire electrode extends from the stop to the endocervical portion of the shaft. In one embodiment of this aspect, the stop subtends an arc greater than about 270°. In another embodiment, the stop subtends an arc of about 360°. In yet another embodiment, the stop is substantially circular in shape. The stop may be affixed to the shaft along a line tangent to the stop. In another embodiment, two ends of the stop may be affixed to the shaft. Alternatively, a single end of the stop may be affixed to the shaft. In yet another embodiment, the stop may include two spaced ends which are disposed at a location spaced from the shaft. In one embodiment, the two ends are rounded and extend away from the endocervical portion and toward the contact portion. In yet another embodiment in which there are two spaced ends, the ends are rounded and extend radially inwardly toward the shaft. In another embodiment in which there are two spaced ends, the stop subtends an arc of greater than 180° between the two spaced ends.  
      In yet another embodiment of this aspect, the shaft extends generally through a center of the stop. In this embodiment, a spoke may extend from the shaft to the stop. This embodiment may also include a second electrode extending from the endocervical portion of the shaft to the stop. In another embodiment of this aspect, a visual marker may be placed on the stop adjacent a location at which the electrode is affixed to the stop. In one variation of this embodiment, the visual marker is disposed on a side of the stop facing the contact portion.  
      In another aspect of this invention, an instrument for excision of a tissue specimen from a transformation zone of a uterine cervix includes an elongated shaft having an endocervical portion disposed adjacent a first end and a contact portion structured to be coupled to a source of electric current disposed at a second end, the endocervical portion being structured to be inserted into a uterine cervix. A stop may be disposed between the endocervical portion and the contact portion and is structured to abut an ectocervix. At least one wire electrode may be electrically coupled to the contact portion and extends from an attachment spot on the stop to the endocervical portion of the shaft. A visually observable marker may be disposed on the stop at the attachment spot, the marker facing the contact portion of the shaft. In one embodiment of this aspect, the marker has a color different from a color of a uterine cervix. In another embodiment, this color may be yellow.  
      In another aspect of this invention, an instrument for excision of a tissue specimen from a transformation zone of a uterine cervix includes an elongated shaft having an endocervical portion disposed adjacent a first end and a contact portion disposed adjacent a second end, a stop disposed between the endocervical portion and the contact portion, the stop being disposed substantially perpendicularly of the shaft, the stop being rounded and having no free ends or edges, and at least one electrode extending from the stop to the endocervical portion of the shaft. In one embodiment of this aspect, the stop has a substantially circular shape. In another embodiment of this aspect, the stop is affixed to the shaft along at least one surface of the stop. In yet another embodiment of this aspect, the stop surrounds the shaft and is coupled to the shaft by at least one spoke.  
      In yet another aspect of this invention, an instrument for excision of a tissue specimen from a transformation zone of a uterine cervix includes an elongated shaft having an endocervical portion disposed adjacent a first end and a contact portion disposed adjacent a second end. A stop is disposed between the endocervical portion and the contact portion, the stop being disposed substantially perpendicularly of the shaft and being rounded and subtending an arc of less than 180° centered on the shaft. This instrument also includes at least one wire electrode extending from the stop to the endocervical portion of the shaft. In one embodiment of this aspect, the instrument includes two spokes extending from the shaft to the stop. In yet another embodiment of this aspect, the stop includes two rounded ends which are curved away from the endocervical portion and toward the contact portion of the shaft. In yet another embodiment of this aspect, the stop subtends an arc of about 90°. In yet another further embodiment of this aspect, the spokes form an angle with respect to the shaft of less than 90° and extend toward the endocervical portion of the shaft.  
      In yet another further aspect of this invention, an instrument for excision of a tissue specimen from a transformation zone of a uterine cervix includes an elongated shaft having an endocervical portion disposed adjacent a first end and a contact portion disposed adjacent a second end in which the endocervical portion is structured to be inserted into the uterine cervix. A stop is disposed between the endocervical portion and the contact portion, and the stop includes a first end which is affixed to the shaft and a second, free end. The stop includes a laterally offset portion which is arcuate in shape and a curved portion disposed between the laterally offset portion and the second end of the stop so that the second end extends away from the endocervical portion and toward the contact portion. This embodiment further includes a wire electrode extending from the endocervical portion of the shaft to a location on the stop disposed between the laterally offset portion and the curved portion. In another embodiment of this aspect, the second end of the stop is rounded, and in yet another embodiment, the second end of the stop has an enlarged, bulbous shape.  
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      The objects, advantages and features of this invention will be more clearly appreciated from the following detailed description, when taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a perspective view of one embodiment of the present invention;  
       FIG. 2  is a distal end view of the embodiment of  FIG. 1 ;  
       FIG. 3  is a cross-sectional side view taken along the line  3 - 3  of  FIG. 1 ;  
       FIG. 4  is a perspective view of another embodiment of the present invention;  
       FIG. 5  is a perspective view of yet another embodiment of the present invention;  
       FIG. 6  is a is a perspective view of yet another embodiment of the present invention;  
       FIG. 7  is a perspective view of yet another embodiment of the present invention;  
       FIG. 8  is a perspective view of another embodiment of the device of  FIG. 7 ;  
       FIG. 9  is a distal end view of the embodiment of  FIG. 7 ;  
       FIG. 10  is a perspective view of yet another embodiment of the device of  FIG. 7 ;  
       FIG. 11  is a perspective view of an alternative embodiment of the device of  FIG. 10 ;  
       FIG. 12  is a perspective view of an alternative embodiment of the device of  FIG. 11 ;  
       FIG. 13  is a perspective view of yet another further embodiment of the present invention;  
       FIG. 14  is a perspective view of an alternative embodiment of the device of  FIG. 13 ;  
       FIG. 15  is a diagrammatic, perspective view of the embodiment of  FIG. 1  being inserted into the vaginal canal and uterine cervix; and  
       FIG. 16  is a diagrammatic perspective view illustrating rotation of the embodiment of  FIG. 1 . 
    
    
     DETAILED DESCRIPTION  
      The present invention relates to instruments which are modifications of the Fischer cone biopsy device, as described in U.S. Pat. Nos. 5,554,159 and 5,403,310, which are incorporated herein by reference in their entirety. In one aspect of the invention, the stop is configured to have no protruding edges or ends. The stop is configured such that the central shaft or body member may be rotated about its axis in either a clockwise or a counterclockwise direction without any protruding edges or ends on the stop that may catch on irregularities in the uterine cervix. In one embodiment of this aspect, the stop has a substantially curved shape throughout its length. Typically, in this embodiment, the stop has a substantially circular configuration. This stop may extend over a complete 360° arc, or it may extend over any arc greater than 180°. In one embodiment, a substantially circular stop is mounted to the central shaft along one edge such that the shaft forms a tangent with respect to the stop. In another embodiment, ends of the stop terminate on the shaft. In yet another embodiment, one end of the stop is affixed to the shaft, while another end of the stop is spaced from the shaft. In yet another embodiment of this aspect, the stop contains two spaced ends which are located in spaced relation with the shaft, and the arm is attached substantially along a tangent. These spaced ends typically are rounded and extend inwardly toward the shaft to avoid catching on irregularities in the uterine cervix. Each embodiment includes at least one electrode extending from the endocervical portion of the shaft to the stop. The electrode could either extend diagonally or include an angular bend between the stop and the shaft.  
      In another embodiment, the stop forms a complete or a partial circle and surrounds the shaft. In one embodiment of this aspect, the stop is connected to the shaft by at least one spoke. In another embodiment of this aspect, the stop is connected to the shaft by two or more spokes. The spokes may either be perpendical to the shaft or form an angle of less than 90° with respect to the shaft and extend toward the endocervical portion. A wire electrode extends between a point on the stop, and the endocervical portion of the shaft. In another embodiment, there are two wire electrodes extending between the stop and the endocervical portion. In yet another embodiment, the stop does not form a complete circle and includes two spaced, rounded ends. The two ends may extend away from the endocervical portion toward the contact portion of the shaft. The stop may subtend an arc of less than 180°, or 90° or less, centered on the shaft.  
      In yet another aspect of the invention, the stop may include two ends, one of which is bonded to the shaft and the other of which is rounded and extends away from the endocervical portion and toward the contact portion. In one embodiment, the stop includes an arcuate, laterally offset portion and a curved portion between the laterally offset portion and the other end. The other end may be enlarged or bulbous in another embodiment.  
      In another aspect of the present invention, a marker is placed on the stop at the point at which each wire electrode is connected thereto. This marker provides a visual indication to the surgeon of the location of the wire electrode.  
      With reference now to the drawings, and more particularly to  FIG. 1  thereof, one embodiment of the instrument of this invention will now be described. Instrument  10  includes an elongated shaft  12 , an electrode  14  and a stop  15 . Typically, shaft  12  is elongated, is generally cylindrical in shape and has a central axis of rotation  13 . Preferably, shaft  12  includes an endocervical portion  16  at one end thereof, a contact portion  18  at the end of shaft  12  opposite the endocervical portion  16  and a vaginal portion  20  between the contact portion  18  and the endocervical portion  16 .  
      In one embodiment, stop  15  extends at a substantially right angle to axis  13  and intersects shaft  12  generally at the juncture of the endocervical portion  16  and the vaginal portion  20 .  
      Typically, shaft  12  includes a core  22  formed of an electroconductive material, such as stainless steel. Surrounding core  22  is a coating  24  of electrically insulating material ( FIG. 3 ). One example of such an electrically insulating material is polytetrafluoroethylene. Other examples may include any other insulating synthetic resins or rubber. Contact portion  18  remains exposed and is not coated with coating  24 . Contact portion  18  typically is an extension of core  22 . Typically, although not necessarily, stop  15  is formed of the same material as shaft  12 , namely an inner core  21  of an electroconductive material surrounded by a coating  23  of electrically insulating material. The core  21  of stop  15  may also be stainless steel.  
      Electrode  14  typically is formed from a thin, electrically conductive wire which is uncoated and exposed. Electrode  14  may be formed of any electrically conductive material, such as a metal, that includes copper, steel, tungsten or the like. As shown in  FIG. 1 , electrode  14  may extend diagonally from the endocervical portion  16  of shaft  12  to a point on stop  15 . As is shown in phantom in  FIG. 3 , in an alternative configuration, electrode  14 A may have a squared-off configuration that includes a bend  11 , intermediate stop  15  and shaft  12 . Electrode  14 A typically intersects shaft  12  at approximately right angles and bend  11  may form an angle somewhat greater than 90°. Bend  11  is typically permanently formed in electrode  14 A. A somewhat stiffer wire, such as a tungsten wire, may be used for electrode  14 A so that bend  11  retains its shape during use.  
      Electrodes  14  and  14 A may be coupled to stop  15  at any one of several locations on stop  15 . Electrode  14  may be positioned at varying angles with respect to shaft  12  as is appropriate for different clinical situations. This angle may be varied by altering the position of the location where electrode  14  is anchored to the endocervical portion of shaft  12 , and/or by altering the diameter of stop  15  and/or by altering the location where electrode  14  is affixed to stop  15 . Typically electrode  14  forms an acute angle greater than about 10° with respect to axis  13  of shaft  12 . It also is preferred that electrode  14  not be coupled to shaft  12  adjacent ends  52  or  54 . Electrode  14  is electrically coupled to core  22  of shaft  12  as well as the electrically conductive core  21  of stop  15 . Electrode  14 A is coupled to both core  21  and core  22  in the same manner as electrode  14 . Preferably, although not necessarily, electrode  14  contacts core  22  of endocervical portion  16  at a point spaced inwardly from the free, distal end of shaft  12 . In one embodiment, electrode  14  is electrically coupled to core  22  by an anchor bead  28  of electrically conductive material which also bonds electrode  14  to shaft  12 . Similarly, in one embodiment, electrode  14  is coupled to core  21  of stop  15  by an anchor bead  26  of electrically conductive material which both anchors electrode  14  to stop  15  and electrically couples electrode  14  to core  21  of stop  15 .  
      In the embodiment of  FIG. 1 , stop  15  has substantially the shape of a circle in a plane that typically, but not necessarily, is perpendicular to axis  13 . In the embodiment of  FIG. 1 , stop  15  includes ends  52  and  54  which are bonded to shaft  12 . Ends  52  and  54  of stop  15  may be bonded to shaft  12  such that the core  21  of stop  15  is in electrical contact with core  22  of shaft  12 . Ends  52  and  54  may be affixed to shaft  12  in any conventional manner, such as by soldering, brazing, welding, gluing and the like.  
      Another embodiment of this aspect of the invention is illustrated in  FIG. 4 . Like numbers are used for like parts where appropriate. As can be seen in  FIG. 4 , stop  45  has substantially the shape of a circle in a plane that typically is substantially perpendicular to axis  13 . In this embodiment, stop  45  is affixed to shaft  12  generally at the junction of vaginal portion  20  and endocervical portion  16  of shaft  12  at a point on the external surface of stop  45 . Shaft  10  may be substantially tangent to stop  45 . In this embodiment, like the embodiment of  FIG. 1 , the core of stop  45  is bonded to or is in electrical communication with the core of shaft  12 . This embodiment may include an electrode  14  coupled to stop  45  at almost any point such that electrode  14  forms an acute angle of greater than 10° with respect to axis  13  of shaft  12 . This embodiment may include a squared-off electrode like electrode  14 A as shown in  FIG. 3 , in place of electrode  14 . In all other respects, the embodiment of  FIG. 4  is the same as that of  FIG. 1 .  
      Another embodiment of this aspect is illustrated in  FIG. 5 . Like numbers are used for like parts where appropriate. In the embodiment of  FIG. 5 , stop  55  has a substantially circular shape in a plane generally perpendicular to axis  13 . In this embodiment, however, stop  55  does not form an entirely closed circle. Rather, stop  55  includes spaced ends  56  and  58  which form arms  62  and  64 . In this embodiment, stop  55  may be bonded to shaft  12  in the manner shown in  FIG. 1  or in the manner shown in  FIG. 4 . The core of stop  55  is electrically coupled to the core of shaft  12 . As shown in  FIG. 5 , typically, electrode  14  is affixed to stop  55  adjacent an end  56 . However, it is to be understood that electrode  14  may be affixed to stop  55  at any other point along stop  55 , so long as electrode  14  forms an angle greater than about 10° with respect to axis  13  of shaft  12 . As in the embodiments of  FIGS. 1 and 4 , electrode  14  is bonded and electrically coupled to the core of stop  55  and to the core of shaft  12 . As in the other embodiments, electrode  14  is bonded to electrocervical portion  16  at a point spaced inwardly from the distal end thereof. The embodiment of  FIG. 5  may include a squared-off electrode like electrode  14 A as shown in  FIG. 3 , in place of electrode  14 .  
      In the embodiment of  FIG. 5 , typically ends  56  and  58  are spaced apart a sufficiently small distance such that when shaft  12  is rotated in either a clockwise or a counter-clockwise direction about axis  13 , ends  56  and  58  do not interfere with the rotation of shaft  10  by catching irregularities of the uterine cervix. Ends  56  and  58  may be spaced apart from one another a distance such that the stop typically subtends an arc of greater than 180°, the center of the arc being axis  13 . The angle subtended by the arc also may be 270° or greater. In one embodiment, ends  56  and  58  are spaced apart a distance of about 2 centimeters or less. It is to be understood, however, that this is merely one example and that other spacings are permitted so long as the stop subtends an arc of greater than 180°.  
      In another embodiment, ends  56  and  58  are configured to have outer surfaces which curve or slant inwardly toward shaft  12 , as shown in  FIG. 5 . Alternatively, ends  56  and  58  may curve and extend away from endocervical portion  16  and toward contact portion  18 . This configuration is shown in conjunction with the embodiments of  FIGS. 11-14 . Moreover, the outer surfaces of ends  56  and  58  are typically smooth or rounded without any sharp edges or ends. These features help prevent ends  56  and  58  from catching any irregularities in the uterine cervix.  
      Ends  56  and  58  may be positioned at almost any location on stop  55  so that resulting arms  62  and  64  of stop  55  are of almost any length. For example, as shown in  FIG. 5 , arms  62  and  64  may be of substantially the same length, so that the gap betweens ends  56  and  58  is substantially centered on and directly opposite the point at which stop  55  is affixed to shaft  12 . However, it is to be understood that ends  56  and  58  can be positioned at a location closer to shaft  12 , so that arms  62  and  64  are of differing lengths.  
      Another embodiment of this aspect of the invention is illustrated in  FIG. 6 . Like numbers are used for like parts where appropriate. In this embodiment, stop  65  includes ends  66  and  68 . Stop  65  may be substantially circular in shape. End  66  is affixed to shaft  12  and its core is electrically coupled to core  22  of shaft  12 . End  68 , on the other hand, is spaced from shaft  12 . As in the embodiment of  FIG. 5 , end  68  is configured so as not to catch irregularities in the uterine cervix. End  68  may accomplish this result by curving inwardly toward shaft  12 , as shown in  FIG. 6 , or by curving away from endocervical portion  16  and toward contact portion  18  in the manner shown in  FIGS. 11-14 , and by being rounded and having no sharp edges or ends thereon. In this embodiment, electrode  14  typically is coupled to the core of stop  65  at a point between ends  66  and  68  such that the angle formed between electrode  14  and axis  13  of shaft  12  is an acute angle greater than about 10°. As in other embodiments, a squared-off electrode  14 A shown in  FIG. 3  may be used in place of electrode  14 . In all other respects, the embodiment of  FIG. 6  is the same as that of  FIGS. 1-5 .  
      Use of the embodiment of  FIG. 1  will now be described with particular reference to  FIGS. 15 and 16 . Each of the devices of  FIGS. 1 and 3 - 6  is operated in substantially the same manner, so that the following description of the use and operation of the embodiment of  FIG. 1  also applies equally to the use and operation of the embodiments of  FIGS. 4-6 . The device of  FIG. 1  is intended to be used with the uterine cervix  36 , portions of which are schematically shown in  FIGS. 15 and 16 . Contact portion  18  is dimensioned to fit into a manipulator  30 . Manipulator  30  is part of a standard electrosurgical generator (not shown). An electric current flows from manipulator  30  through uncovered contact portion  18  and through core  22  to electrode  14 . A return flow of current passes through an electrode attached elsewhere to the patient&#39;s body (not shown). Shaft  12  of instrument  10  is dimensioned so that contact portion  18  is always disposed outside the vaginal canal  32  when the endocervical portion  16  is inserted into the endocervical canal  34  of the uterine cervix  36 .  
      Endocervical portion  16  of the instrument is inserted axially through the vaginal canal  32  and into the endocervical canal  34  of the uterine cervix  36  until electrode  14  contacts an area of the ectocervix  38  which is free from all evident pathology. A current is imparted to electrode  14  through manipulator  30 . Electrode  14  cuts through the tissue of the ectocervix  38  allowing the endocervical portion  16  to be advanced axially in the direction shown by the arrow in  FIG. 15  into the endocervical canal  34  until stop  15  abuts the ectocervix  38 , as shown in  FIG. 16 . In this manner, an axial cut is made in the transformation zone  40  of the uterine cervix  36  by electrode  14 . Because stop  15  is seated stably on ectocervix  38  and the electrode  14  is taut, the physician has good control of the cutting action and the extent of penetration is limited.  
      At this point, current to electrode  14  may be discontinued to permit preparation of the next step. Once preparation is completed, current may again be imparted to electrode  14 . The instrument is rotated through one full 360° revolution in one direction about its axis  13  as shown by the arrows in  FIG. 16 . Because there are no edges that would catch irregular portions of the uterine cervix, the instrument may be rotated in either a clockwise or a counter-clockwise direction. Because rotation takes place with the endocervical portion  16  in the endocervical canal  34  and with the stop  15  abutting the ectocervix  38 , the instrument is stabilized, allowing for a tissue specimen  42  to be excised from the transformation zone  40  of the uterine cervix  36 .  
      Once the excision is complete, current is discontinued to electrode  14  and the instrument is withdrawn from the endocervical canal  34  and the vaginal canal  32 , simultaneously withdrawing the tissue specimen  42  along with it. The tissue specimen  42  typically will be conical in shape if an electrode  14  is employed. If a squared-off electrode  14 A is employed, tissue specimen  42  will have a configuration approximating that of a truncated cone. In either case, a defined, controlled amount of cervical tissue is provided to make pathological interpretation easier and more reliable.  
      It should be understood that if only a wedge-shaped specimen is desired, the specimen may be cut by limiting the extent of rotation of the shaft  12  to an angle of less than 360°. Thereafter, the instrument is slowly axially withdrawn from the endocervical canal  34  while power is still applied to electrode  42  to cut the other end of the wedge-shaped section.  
      The current employed for the foregoing excision process is one appropriate for cutting and coagulation. Typically, an output power in the range of 50-70 watts is suitable.  
      In the embodiments of  FIGS. 1 and 3 - 6 , shaft  12  is typically about 120-140 millimeters in length. One preferred length is about 130 millimeters. Endocervical portion  16  may be about 18-22 millimeters in length, with about 20 millimeters being a suitable length. Vaginal portion  20  typically is in the range of about 80-100 millimeters in length with a suitable length being about 90 millimeters. Contact portion  18  typically is about 8-12 millimeters in length although it may be as long as about 20 millimeters. Stops  15 ,  45 ,  55  and  65  typically have a diameter of about 15-20 millimeters. Electrodes  14  and  14 A typically are attached to shaft  12  at a location spaced inwardly from the distal end thereof a distance of about 2 to about 5 millimeters.  
      Another aspect of this invention will now be described with respect to  FIGS. 7, 8 ,  10 ,  11  and  12 . Like numbers will be used for like parts where appropriate. Instrument  70  of  FIG. 7  includes a shaft  12  which has an endocervical portion  16  at one end, contact portion  18  at the other end, and a vaginal portion  20  therebetween. A stop  75  is disposed approximately at the juncture of the endocervical portion  16  and the vaginal portion  20 . Stop  75  is curved, and in one embodiment, may be formed as a circle in a plane generally perpendicular to axis  13  of shaft  12 . In the embodiment of  FIGS. 7 and 10 , stop  75  may form a complete circle which surrounds shaft  12 . Typically, although not necessarily, shaft  12  is disposed at the center of the circle formed by stop  75 . Stop  75  is supported with respect to shaft  12  by one or more spokes  74  which extend from shaft  12  to stop  75 . Two spokes  74  are illustrated in  FIGS. 7, 8  and  10 . Spokes  74  may extend at a substantially perpendicular angle with respect to shaft  12 , as shown in  FIG. 7 , or spokes  74  may form an acute angle with respect to shaft  12 , pointing toward endocervical portion  16  and away from contact portion  18 , as shown in  FIG. 10 . Spokes  74  typically are formed of a material which is sufficiently rigid to maintain the spacing between stop  75  and shaft  12  and to prevent rotation of stop  75  about shaft  12 . A typical example of a suitable material is stainless steel. Spokes  74  provide an electrical connection between stop  75  and manipulator  30 . Stop  75 , as with stop  15 , is typically formed of a conductive core material surrounded by a non-conductive layer. This embodiment may include at least one electrode  14 , as illustrated in  FIG. 10 , or as illustrated in  FIG. 7 , two electrodes  14 . Each electrode  14  extends from a point spaced inwardly from the distal end of the endocervical portion  16  of shaft  12  to a point on stop  75 . If two electrodes are used, typically they are diametrically opposed about shaft  12  or are separated by an arc of 180° centered on axis  13 . A suitable bead  28  may be utilized to bond each electrode  14  to shaft  12  and to electrically couple electrode  14  to the core of shaft  12 . Similarly, an anchor bead  26  of electrically conductive material which is in electrical contact with the core of stop  75  may also be used to bond each electrode  14  to stop  75 . It will be appreciated that, as with the other embodiments, squared-off electrodes like electrode  14 A shown in  FIG. 3  may be used in place of diagonally extending electrodes  14 .  
      Preferably, spokes  74  are positioned so that they are offset radially on shaft  12  with respect to electrodes  14 . As shown in the example of  FIG. 7 , spokes  74  form an angle of about 90° with respect to electrodes  14 . In this way, spokes  74  do not obscure the surgeon&#39;s view of electrodes  14  through stop  75 .  
      Since stop  75  forms a complete circle, there are no sharp edges or ends or other portions thereof which would inadvertently catch the irregular portions of the uterine cervix. Therefore, complete and smooth rotation of shaft  12  about axis  13  is permitted.  
      In the embodiment illustrated in  FIG. 8 , stop  85  may not be formed as a complete circle. Stop  85  of  FIG. 8  has a gap between ends  76  and  78  disposed somewhere along the circumference of stop  85 . Preferably, ends  76  and  78  are configured like ends  56  and  58  of  FIG. 5 , i.e., they are rounded and curve inwardly toward shaft  12 , or curve and extend toward contact portion  18  and away from endocervical portion  16 . Ends  76  and  78  preferably have no sharp edges or ends so that they do not catch irregular portions of the uterine cervix. Stop  85  typically subtends an arc greater than 180°, and typically greater than 270°, the arc being centered on axis  13 . In all other respects, the embodiment of  FIG. 8  is like that of  FIG. 7 .  
      In the embodiment of  FIG. 10 , there is one electrode  14  and two spokes  74 . In this embodiment, stop  75  forms a complete circle. Spokes  74  form an acute angle with respect to shaft  12  and typically point or extend away from shaft  12  toward endocervical portion  16  and away from contact portion  18 . Typically, the angle formed between spokes  74  and shaft  12  may range from about 10° to about 80°. One preferred angle is about 45°. This configuration minimizes contact between spokes  74  and cervix  36 , to minimize the likelihood that spokes  74  would catch on the cervix and interfere with the smooth rotation of shaft  12  during surgery. In other respects, the embodiment of  FIG. 10  is like that of  FIG. 7 .  
      Another embodiment of this aspect of the invention is illustrated in  FIG. 11 . Like numbers are used for like parts where appropriate. Instrument  110  includes a shaft  12  which has an endocervical portion  16  at one end, contact portion  18  at the other end, and a vaginal portion  20  therebetween. A stop  115  is disposed approximately at the juncture of the endocervical portion  16  and the vaginal portion  20 . Stop  115  is curved, and in one embodiment, may be formed as a partial circle in a plane generally perpendicular to axis  13  of shaft  12 . However, stop  115  need not be in a plane perpendicular to axis  13 . Preferably, stop  115  subtends an arc which is centered along axis  13 . Stop  115  typically subtends an arc less than 270°, and preferably less than 180°. A typical arc subtended by stop  115  is approximately 90°. Stop  115  is supported with respect to shaft  12  by one or more spokes  112 . Spokes  112  extend from shaft  12  at substantially an angle of 90° with respect to shaft  12 . In the particular embodiment of  FIG. 11 , two spokes  112  are illustrated. Spokes  112  are formed of the same material as spokes  74 . Similarly, stop  115  is formed of the same material as stop  15 . Moreover, shaft  12  is substantially identical to shaft  12  of  FIG. 1 . The embodiment of  FIG. 11  also includes one electrode  14  which extends from a point spaced inwardly from a distal end of the endocervical portion  16  of shaft  12  to a point on stop  115 . Preferably, electrode  14  is offset from spokes  112  to allow the surgeon to view electrode  14 . In the embodiment shown in  FIG. 11 , electrode  14  is substantially centered between the points at which spokes  112  are attached to stop  115 . A suitable anchor bead  28  may be utilized to bond electrode  14  to shaft  12  and to electrically couple electrode  14  to the core thereof. Similarly, an anchor bead  26  of electrically conductive material which is in electrical contact with the core of stop  115  may also be used to bond electrode  14  to stop  115 . It will be appreciated that, as with the other embodiments, a squared-off electrode, like electrode  14 A shown in  FIG. 3 , may be used in place of a diagonally-extending electrode  14  as shown in  FIG. 11 .  
      Stop  115  includes ends  116  and  114 . Ends  116  and  114  may be rounded and extend inwardly like ends  56  and  58  of the embodiment of  FIG. 5 . In an alternative embodiment, as illustrated in  FIG. 11 , ends  114  and  116  are again rounded, but curve and extend generally axially away from endocervical portion  16  and toward contact portion  18 . Since ends  114  and  116  extend away from endocervical portion  16 , in use, these ends  114  and  116  also extend away from the uterine cervix  36 . In this way, ends  114  and  116  are less likely to engage a portion of the uterine cervix  36  which could interfere with the free rotation of shaft  12  about its axis  13 .  
       FIG. 12  illustrates an alternative embodiment of  FIG. 11  and like numbers are used for like parts where appropriate.  FIG. 12  is substantially identical to that of  FIG. 11  in all respects except that spokes  112  form an acute angle with respect to shaft  12 . Spokes  112  typically form an angle of between 10° and 80° with respect to shaft  12 . One typical angle is 45°. Spokes  112  point or extend away from shaft  12  and away from contact portion  18  and toward endocervical portion  16 . This angular configuration minimizes contact between uterine cervix  36  and spokes  112  to minimize the likelihood that spokes  112  could catch on the uterine cervix and interfere with the free rotation of shaft  12 .  
      Yet another aspect of this invention will now be described with respect to  FIGS. 13 and 14 . Like numbers will be used for like parts where appropriate. Instrument  130  of  FIG. 13  includes an electrode  14  and a shaft  12  which has an endocervical portion  16  at one end, a contact portion  18  at the other end, and a vaginal portion  20  therebetween. A stop  135  is disposed approximately at the juncture of the endocervical portion  16  and the vaginal portion  20 . Stop  135  is bonded at end  134  directly to shaft  12  so that the core of stop  135  is affixed to and is in electrical contact with the core of shaft  12 . Portion  136  of stop  135  between ends  132  and  134  typically is laterally offset from the longitudinal plane extending through electrode  14  and shaft  12 . As a result, the physician can see most of the cervical area which is being cut by electrode  14  and which would otherwise be obscured by stop  135 . Portion  136  may be arcuate in shape and have either a small or a large radius of curvature. Electrode  14  extends from a location on stop  135  between portion  136  and curve  138  to endocervical portion  16  of shaft  12  at a point spaced from the distal end thereof. It should be understood that while electrode  14  is shown as being linear and extending diagonally from stop  135  to endocervical portion  16 , electrode  14  may be similar to electrode  14 A of  FIG. 3  and have a squared-off configuration. One end of electrode  14  may be bonded by an anchor bead  26  of electrically conductive material to the core of shaft  12 , and the other end of electrode  14  may be bonded by a bead  28  of an electrically conductive material to stop  135  and is in electrical contact with the core of stop  135 .  
      Stop  135 , in this embodiment, typically includes curve  138  just beyond the point at which electrode  14  is attached to stop  135 , but before end  132 . Curve  138  causes end  132  to extend away from endocervical portion  16  and toward contact portion  18 . Curve  138  should be smooth and rounded so that no sharp ends or edges are provided. In this way, end  132  extends away from uterine cervix  36  so as not to be inadvertently caught on uterine cervix  36  during use. End  132  is also smoothly rounded to avoid any sharp ends or edges.  
      An alternative embodiment of this aspect is shown in  FIG. 14 . Like numbers are used for like parts where appropriate.  FIG. 14  has a stop  145  which includes ends  142  and  144 . End  144  is bonded to shaft  12  and is in electrical communication with the core of shaft  12 . Stop  145 , like stop  135 , has a portion  146  which is laterally offset from the longitudinal plane extending through electrode  14  and shaft  12 , to allow the surgeon to see the cervical area during surgery. Stop  145  includes curve  148  beyond the point where electrode  14  is bonded to the core of stop  145  by bead  26 . End  142  also extends away from endocervical portion  16  and toward contact portion  18 . The primary difference between the embodiment of  FIG. 14  and that of  FIG. 13  is that the embodiment of  FIG. 14  includes an end  142  which is slightly enlarged or is bulbous. The substantially spherical shape of end  142  assures that there are no sharp edges or ends which could catch on the uterine cervix. In all other respects, the embodiment of  FIG. 14  is substantially identical to that of  FIG. 13 .  
      Use and operation of the embodiments of  FIGS. 13 and 14  is substantially identical to that as described with respect to the embodiments of  FIGS. 1 and 3 - 6 , and need not be described further herein.  
      Operation of the embodiments of  FIGS. 7, 8 ,  10 ,  11 ,  12 ,  13  and  14  is substantially identical to the operation of the embodiments of  FIGS. 1 and 3 - 6  as illustrated with respect to  FIGS. 15 and 16 . The only difference of significance in the operation of the embodiments of  FIGS. 7 and 8  is that because two electrodes  14  are provided, the physician only needs to rotate shaft  12  through 180°. Shaft  12  may be rotated in either a clockwise or a counterclockwise direction. It is to be understood that in  FIGS. 10, 11 ,  12 ,  13  and  14 , since only one electrode  14  is provided, shaft  12  may be rotated a full 360° in either a clockwise or a counterclockwise direction. Because rotation takes place with the endocervical portion  16  in the endocervical canal  34  and with stop  75 ,  85 ,  115 ,  135  or  145  abutting the ectocervix  38 , the instrument is stabilized, allowing for a suitably shaped tissue specimen to be excised from the transformation zone  40  of the uterine cervix  36 . The tissue specimen will be conically shaped if diagonal electrodes, as shown in  FIGS. 7, 8 ,  10 ,  11 ,  12 ,  13  and  14  are used. If a squared-off electrode, like that shown in  FIG. 3  is used, a truncated cone specimen will be obtained.  
      As previously discussed, if only a wedge shaped specimen is desired, shaft  12  may be rotated through an arc less than 180° for two electrodes  14 , as shown in  FIGS. 7 and 8 , or an arc less than 360° for one electrode  14  as shown in  FIG. 10 . The instrument is then slowly withdrawn in an axial direction to cut the end of the section.  
      In a typical embodiment of  FIGS. 7, 8 ,  10 ,  11 ,  12 ,  13  and  14 , shaft  12 , endocervical portion  16 , vaginal portion  20 , and contact portion  18  all have about the same dimensions as those set forth above for the embodiments of  FIGS. 1 and 3 - 6 . Typically, stops  75 ,  85 ,  115 ,  135  and  145  have a diameter of between about 20 and about 40 millimeters, with about 30 millimeters being a suitable diameter. Electrodes  14  are positioned on shaft  12  in substantially the same locations at substantially the same angles as the electrodes  14  in the embodiments of  FIGS. 1 and 3 - 6 .  
      In each of the embodiments of FIGS.  1 ,  3 - 8 ,  10 ,  11 ,  12 ,  13  and  14 , the surgical procedure may be viewed through the space between respective stops  15 ,  45 ,  55 ,  65 ,  75 ,  85 ,  115 ,  135  and  145  and shaft  12 . As a result, the surgeon can see most of the cervical area which is being cut by the electrode  14  or  14 A. Nonetheless, once electrode  14  or  14 A is embedded in the cervical tissue which is being cut, electrode  14  or  14 A is no longer visible to the surgeon. Therefore, the exact location of the electrode is not always easily determined by the surgeon once the cutting operation begins.  
      In another aspect of the invention, a marker may be provided on the stop to identify the location of the electrode(s)  14  or  14 A. One embodiment of this aspect is illustrated in  FIG. 2  with respect to the invention of  FIG. 1 . Visual marker  90  is positioned at least on the side of stop  15  facing contact portion  18  and facing away from the endocervical portion  16 . Marker  90  is located directly opposite the point on stop  15  at which electrode  14  or  14 A is attached to stop  15 . Since the surgeon knows that the other end of electrode  14  or  14 A is affixed to shaft  12 , using marker  90  the surgeon can readily locate the entire length of electrode  14  or  14 A, even if electrode  14  or  14 A is buried in tissue. Marker  90  may be anything that provides to the surgeon a visual indication of the end of electrode  14  or  14 A. In one example, marker  90  is a stripe of paint in a readily visually recognized color that contrasts with the colors present in the uterine cervix  36 . One example is yellow. Other examples include white or gold. In another example, marker  90  may be a visually observable bump formed on stop  15 . In yet another example, marker  90  may be a reflective or sparkling coating which allows a limited amount of light to be reflected back to the surgeon. Another example includes a wrapping of wire about stop  15 .  
      Another embodiment of this aspect is illustrated in  FIG. 9 .  FIG. 9  shows similar markers  90  for the embodiment of  FIG. 7 . Since there are two electrodes  14  or  14 A in  FIG. 7 , there typically would be two markers  90  as shown in  FIG. 9 , providing an indication of the end of each electrode  14  or  14 A. Markers  90  in  FIG. 9  may be identical to markers  90  of  FIG. 2 . Since the surgeon knows that the other end of each electrode  14  or  14 A is affixed to endocervical portion  16  of shaft  12 , these markers  90  permit the surgeon to visually locate both electrodes  14  or  14 A.  
      It will be appreciated that because of the substantially circular configuration of stops  15 ,  45 ,  55 ,  65 ,  75 ,  85 ,  115 ,  135  and  145  and the rounded ends of stops  55 ,  65 ,  85 ,  115 ,  135  and  145 , there are no sharp edges or ends that could be caught on any irregularities of the uterine cervix. As a result, the shapes of these stops allow them to pass smoothly over any irregularities permitting a more precise and error-free surgical excision. Moreover, in the embodiment of  FIG. 7 , when two electrodes  14  are employed, the instrument need only be rotated through 180°, allowing an easier and more precise surgical incision without concern that movement of the surgeon&#39;s fingers, which may be required to rotate the instrument through an entire 360°, would cause any problems with the surgical procedure. Furthermore, the provision of an open circular shape for the stop allows a surgeon to clearly view the procedure. Finally, the provision of markers on the side of the stop facing the surgeon permits the surgeon to easily locate the electrode(s) at all times during the surgical procedure.  
      Modifications and improvements will occur within the scope of this invention to those skilled in the art. The above description is intended to be exemplary only, the scope of the invention being defined by the following claims and their equivalents.