Abstract:
A device for morcellating tissue within a body cavity of a patient comprises a stationary tube ( 8 ) having a distal end portion, and a bipolar electrosurgical electrode assembly ( 13 ) located at the distal end of the tube. The electrosurgical electrode assembly ( 13 ) comprises first and second electrodes ( 14, 16 ) separated by an insulation member ( 15 ). When an electrosurgical cutting voltage is applied to the electrode assembly ( 13 ), and relative movement is initiated between the tube ( 8 ) and the tissue, a slug of resected tissue is formed within the tube such that it can be removed from the body cavity of the patient. The bipolar electrosurgical assembly ( 13 ) has a first circumferential region (A) and a second circumferential region (B), the first circumferential region (A) being longer than the second circumferential region (B), the bipolar electrosurgical assembly being adapted to cut tissue preferentially in the first circumferential region (A) as compared with the second circumferential region (B).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a bipolar electrosurgical instrument for use in the bulk removal of tissue, as in a laparoscopic hysterectomy. 
         [0002]    In a laparoscopic hysterectomy, the body of the uterus is resected from the stump or fundus, and then removed from the operative site. To enable the uterus to be removed through a limited surgical opening, it is desirable to morcellate it into relatively smaller pieces of tissue, which are easier to remove. Our pending patent application, published as WO05/112806 describes an electrosurgical morcellator for the bulk removal of tissue. The present invention relates to an improvement to this type of instrument. 
         [0003]    A known problem with morcellating devices is their tendency to “coring”, in which the tip of the morcellator dives into the tissue in a relatively uncontrolled way. A preferred cutting technique is to use the device in a “peeling” action, in which the cutting instrument removes tissue from the outside of an organ, rather like the peeling of an apple or orange. Peeling is preferred to coring for several reasons. A first reason is that the tip of the morcellator is more visible to the surgeon if it is peeling around the outside of the tissue, as opposed to being buried within the tissue as happens when the instrument is producing a core of tissue. Peeling produces a more continuous cut, and also a more continuous mass of uncut tissue. The more continuous cut means that the process can be completed more quickly, with the surgeon having to re-engage the tissue less often. Peeling from the outside of a solid organ or mass of tissue leaves behind a more continuous mass of tissue, and less tissue fragments as compared with coring. 
         [0004]    Published US patent application 2008/0039883 describes the problem with coring, and provides a mechanical solution in the form of a protrusion situated at the distal tip of the instrument. The present invention attempts to provide an alternative solution, more suited to use with an electrosurgical morcellator. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a device for morcellating tissue within a body cavity of a patient, the morcellating device comprising a stationary tube having a distal end portion, the distal end portion including a stationary bipolar electrosurgical electrode assembly including first and second electrodes located at the distal end of the tube and separated one from the other by an insulation member, the arrangement being such that, when an electrosurgical cutting voltage is applied to the electrode assembly, tissue can be pulled against the distal end of the tube to form a slug of resected tissue within the tube, the bipolar electrosurgical assembly having a first circumferential region and a second circumferential region, the first and second electrodes being provided in the first circumferential region, the first circumferential region extending continuously around at least 50% of the tube, and the bipolar electrosurgical assembly being adapted to cut tissue preferentially in the first circumferential region as compared with the second circumferential region. 
         [0006]    By providing an electrosurgical cutting assembly in which cutting is performed preferentially in a first circumferential region, and either less effectively or not at all in a second circumferential region, the cutting instrument is unable to cut around the whole of the 360° circumference of the tube. This means that the cutting tip is less likely to be able to remove a core of tissue and become buried within the body of the organ being morcellated. With a section of the tissue being less easily cut, the morcellating instrument removes tissue at the surface of the organ in a more controlled peeling action. 
         [0007]    The second circumferential region should not be so great as to substantially affect the cutting capability of the instrument, and so the first circumferential region extends around at least 50% of the circumference of the tube. Other convenient arrangements have the second circumferential region constituting approximately 33%, 20% or even 10% of the circumference of the tube. 
         [0008]    A convenient way of ensuring that the second circumferential region cuts less effectively than the first circumferential region is to ensure that the device is such that neither the first electrode nor the second electrode occupies the second circumferential region. In this way, the electrosurgical cutting assembly is unable to perform an effective cut around its entire circumference. Either the first (active) electrode or the second (return) electrode can be provided in this way to disrupt the cutting action. 
         [0009]    In one arrangement, an insulator occupies the second circumferential region. Thus, the first (active) electrode or the second (return) electrode extends continuously around the first circumferential region, but is replaced with an insulator in the second circumferential region. The electrosurgical cutting assembly is unable to cut effectively in the region where the first electrode or the second electrode is replaced by an insulator, thereby providing the uncut portion of tissue which is effective in promoting peeling and discouraging coring of tissue. 
         [0010]    In an alternative arrangement, the second circumferential region is not merely provided with an insulator instead of the first electrode or the second electrode, but instead comprises a third electrode spaced from both the first and second electrodes by one or more insulating sections. Preferably, the first, second and third electrodes each have separate leads connected thereto, such that the third electrode is capable of being selectively switched in and out of common electrical potential with that of at least one of either the first and second electrodes. In this way, the third electrode can be selectively switched “on” so as to provide a cutting action in collaboration with the first circumferential region, or alternatively switched “off” so as to act as an insulator as previously described. The instrument can, therefore, be controlled by the user, either to peel tissue with the anti-coring system in operation; or, if coring is required for some reason (or if the maximum cutting potential is required for a particularly difficult tissue extraction), the third electrode can be energised to provide cutting around the whole 360° circumference of the tube. 
         [0011]    Conceivably, either the first electrode or the second electrode is split into three or more circumferential sections, each separated from adjacent circumferential sections by means of insulators. In this arrangement, the three or more circumferential sections preferably each have separate leads connected thereto, such that each circumferential section is capable of being switched into, and out of, common electrical potential with other circumferential sections. The device preferably carries a switch means capable of changing the circumferential section or sections that are switched out of common electric potential with the other circumferential sections. In this way, any one or more of the three or more circumferential sections can be selectively switched to become insulated from the other sections, and hence become the second circumferential region described heretofore. This arrangement allows the user of the instrument to select which circumferential region of the tube is to become less effective at cutting and hence provide the anti-coring effect. It is, therefore, not necessary for the user to re-orient the tube to accommodate a fixed anti-coring region, and the user is able to change the anti-coring region depending on the orientation of the instrument. It is also possible for the user to increase or decrease the number of sections that are insulated, so as to be able to increase or decrease the anti-coring region as required. Conceivably, the switch means comprises a rotatable collar carried on the device. 
         [0012]    Alternatively, there is provided means for determining the orientation of the tube, and for activating the switch means so as to vary the circumferential section or sections that are switched out of common electric potential with the other circumferential sections depending on the orientation of the tube. In this way, the insulated section is maintained in a predetermined orientation, regardless of which way the tube is oriented by the user. For example, it has been found advantageous to maintain the non-cutting section towards the outside of the body of tissue, on the “top” of the device as it is being used. This keeps the morcellator towards the surface of the tissue, and prevents it from becoming buried within the tissue. By automatically orienting the non-cutting section regardless of orientation, the user does not need to make manual adjustments as the device is being used. 
         [0013]    In one convenient arrangement, the tube is provided with a marker in alignment with the second circumferential region, to highlight its position to a user of the device. Thus the user always knows which portion of the tube is provided with the anti-coring effect, regardless of whether the circumferential region is fixed or changeable, manually or automatically. 
         [0014]    In an alternative arrangement, the second circumferential region is provided by covering the first or second electrode with an electrically-insulating mask. This is in contrast to earlier described arrangements in which the first electrode or the second electrode is interrupted in the second circumferential region, either by an insulating section or by a third electrode. In this alternative arrangement, the first electrode or the second electrode runs continuously around the circumference of the tube, but is masked by the electrically-insulating mask in the second circumferential region. In one arrangement, the mask is selectively detachable from the first electrode or the second electrode. Alternatively, the mask is selectively deployable between a first position in which it obscures the first electrode or the second electrode, and a second position in which it does not obscure the first electrode or the second electrode. Conveniently, the mask is selectively advanced and retracted between the first and second positions. Whichever arrangement is employed, the mask prevents effective cutting of tissue in the second circumferential region and provides the anti-coring effect previously described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will now be described in more detail, by way of example, with reference to the drawings, in which: 
           [0016]      FIG. 1  is a schematic side view, partly in section, of a morcellating device constructed in accordance with the invention; 
           [0017]      FIG. 2  is an enlarged view of a part of the device shown in  FIG. 1 , 
           [0018]      FIG. 3  is an enlarged view of an alternative embodiment of a morcellating device constructed in accordance with the invention; 
           [0019]      FIG. 4  is an enlarged view of a further embodiment of a morcellating device constructed in accordance with the invention; 
           [0020]      FIGS. 5A &amp; 5B  are enlarged views of different parts of a further embodiment of a morcellating device constructed in accordance with the invention; 
           [0021]      FIG. 6  is an enlarged view of yet another embodiment of a morcellating device constructed in accordance with the invention; 
           [0022]      FIG. 7  is an enlarged perspective view of a further embodiment of a morcellating device constructed in accordance with the invention; and 
           [0023]      FIGS. 8 &amp; 9  are enlarged views, partly in section, of the device of  FIG. 7 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0024]    Referring to  FIG. 1 , a morcellating system comprises a morcellating device shown generally at  1 , a tissue-pulling device shown generally at  2 , and an electrosurgical generator  3 . The generator  3  is connected to the morcellating device  1  by means of a cable  4 , and to the tissue-pulling device  2  by means of a cable  5 . The generator  3  is controlled by means of a footswitch  6 . 
         [0025]    As shown in  FIGS. 1 and 2 , the morcellating device  1  comprises a handle  7  and a cylindrical tube  8 . The cylindrical tube  8  is hollow, and defines a lumen  9  therein. The proximal end of the tube  8  extends from the handle  7  as shown at  11 , and the distal end of the tube is provided with an electrosurgical electrode assembly  13 . The electrosurgical electrode assembly  13  comprises an active tissue-cutting electrode  14 , and an insulation member  15 , both extending around the circumference of the tube  8 . The insulation member  15  separates the active electrode  14  from a return electrode  16 , also located on the tube  8 . 
         [0026]    The active electrode  14  extends around the circumference of the tube  8 , and is connected to one pole of the generator  3 , via the cable  4 . The return electrode  16  is connected to the other pole of the generator  3 , via the cable  4  and additional wiring (to be described later). In this way, the electrodes  14  and  16  constitute the bipolar electrode assembly  13 , which, when energised by the generator  3 , is capable of cutting tissue coming into contact with the distal end of the tube  8 . 
         [0027]    The tissue-pulling device  2  comprises a tubular shaft  18 , at the proximal end of which is a scissors-type handle mechanism  19 , having a first handle  20  and a second handle  21 . The second handle  21  is pivotable with respect to the first handle  20 , about a pivot pin  22 . Pivoting of the second handle  21  causes longitudinal movement of a push rod  23  extending through the shaft  18  to the distal end thereof. 
         [0028]    At the distal end of the shaft  18  is a jaw assembly  24 , with a first jaw member  25  and a second jaw member  26  movable between open and closed positions by the movement of the push rod  23 . The tissue-pulling device  2  is manually translatable in a longitudinal manner within the lumen  9  of the morcellating device  1 . The jaw members  25  and  26  are electrically connected to the shaft  18 , and the shaft is optionally electrically connected, via the cable  5  and a connector  28 , with the generator  3 . The shaft  18  is connected to the same pole of the generator  3  as the return electrode  16 . 
         [0029]    The operation of the morcellating system is as follows. The tube  8  of the morcellating device  1  is inserted into the body of a patient, typically through a trocar (not shown), or optionally directly into an incision made in the body of the patient. The device  1  is brought into position adjacent to the tissue to be removed, which is typically a resected uterus in the case of a laparoscopic hysterectomy. The tissue-pulling device  2  is then inserted through the lumen  9  of the morcellating device  1 . The handle  21  is operated to open the jaw assembly  24 , and the tissue-pulling device  2  is manoeuvred so that tissue from the uterus is located between the jaw members  25  and  26 . The handle  21  is then operated to close the jaw assembly  24 , grasping tissue therein. 
         [0030]    The surgeon operates the footswitch  6  to operate the generator  3  so that an electrosurgical cutting voltage is supplied between the active electrode  14  and the return electrode  16 . As mentioned previously, the push rod  23  and the jaw assembly  24  are also electrically connected to the same pole of the generator  3  as the return electrode  16 , and so both the return electrode and the jaw assembly constitute a return. With tissue firmly grasped in the jaw assembly  24 , the tissue-pulling device  2  is slowly withdrawn from the tube  8 , pulling the tissue against the distal end of the tube and against the active electrode  14 . As the tissue contacts the active electrode  14 , it is vaporised, allowing the tissue-pulling device  2  to be withdrawn further into the tube  8 . In this way, a cylindrical slug of tissue is formed in the tube  8 , the tissue being withdrawn though the proximal end  10  of the morcellating device  1  (which remains outside the body of the patient) for disposal. 
         [0031]    The tissue-pulling device  2  can then be re-inserted into the tube  8  such that a further slug of tissue can be removed from the body of the patient. By repeating this process, large quantities of tissue can be removed from the patient in a relatively short time, such that the entire uterus can be removed, if necessary, while still employing a laparoscopic approach. 
         [0032]      FIG. 2  shows the distal end of the tube  8  according to a first embodiment of the invention, in which the active electrode  14  extends around the circumference of the tube  8  in a first circumferential region A constituting more than 50% of the circumference of the tube, but does not extend into a second circumferential region B constituting less than 50% of the circumference of the tube. In the second circumferential region B there is merely the exposed insulation member  15 . The return electrode  16  extends completely around the tube  8  as shown. Leads  31  and  32  respectively connect the electrodes  14  and  16  to the generator  3 . When the electrosurgical cutting voltage is supplied between the electrodes  14  and  16 , and tissue is pulled against the electrodes by the tissue-pulling device  2 , the tissue will be electrosurgically cut in the region A, but remain unsevered in the region B. More and more tissue can be pulled against the tube  8  by the retraction of the tissue-pulling device  2 , and the result will be a peeling of tissue with a segment of the tissue remaining connected to the uterus adjacent to the region B. In this way, the tube  8  will remain towards the edge of the uterus, rather than being buried into the tissue to produce a coring action. 
         [0033]      FIG. 3  shows an alternative distal arrangement in which the active electrode  14  extends continuously around the circumference of the tube  8 , but the return electrode  16  extends solely around region A, and is replaced by an insulator  30  in region B. As the electrosurgical cutting action will only be effective where the active and return electrodes  14  and  16  are in close proximity to one another, this arrangement will function in a similar fashion to that of the device of  FIG. 2 . 
         [0034]      FIG. 4  shows a further arrangement, somewhat similar to that of  FIG. 3  in that the active electrode  14  extends around the circumference of the tube in a first circumferential region A, but does not extend into a second circumferential region B. However, in the region B there is provided a further active electrode  33  spaced from each circumferential end of the electrode  14  by insulating spacers  34  and  35 . The return electrode  16  extends completely around the circumference of the tube  8  as shown. The lead  31  connects the active electrode  14  to the generator  3 , the lead  32  connects the return electrode  16  to the generator, and a further lead  36  connects the further electrode  33  to the generator. The further electrode  33  is connected to the generator  3  via a switching device (not shown), the operation of which will now be described. 
         [0035]    In a first situation, the switching device is set so that the electrosurgical cutting voltage is supplied solely to the active electrode  14 , such that the voltage is supplied between the electrodes  14  and  16  in the region A, with no cutting action being created in the region B. This is the anti-coring cutting action previously described with reference to  FIGS. 2 and 3 . However, there may be times when the user of the morcellating device  1  needs to provide a cutting action completely around the circumference of the tube  8 , either because the user wants to create a coring action, or because the nature of the tissue being treated means that the maximum cutting activity is needed. In this circumstance, the switching device is set so that the electrosurgical cutting voltage is supplied to both active electrodes  14  and  33  such that the voltage is supplied not only between the electrodes  14  and  16  in the region A, but also between the electrodes  33  and  16  in the region B. This means that the cutting action is available around the complete circumference of the tube  8 , when desired. In an alternative arrangement, the further active electrode  33  is supplied with a lower voltage than the electrosurgical cutting voltage, such that it is not capable of cutting tissue but perhaps capable of coagulating tissue in combination with the return electrode  16 . This will still provide the anti-coring action described previously, and may be useful where the tissue being dissected remains vascular, and where excessive bleeding is to be prevented. 
         [0036]      FIGS. 5A and 5B  show an even more sophisticated arrangement, in which a series of active electrodes  14 A,  14 B,  14 C,  14 D etc. are disposed around the circumference of the tube  8 , each active electrode being separated from circumferentially adjacent active electrodes by insulating spaces  37 . Each active electrode  14 A to  14 D is provided with its own lead (not shown), so that any combination of active electrodes can he energised or not, depending on the circumstances. A rotatable collar  38  is provided on the tube  8 , the collar having a series of contacts (not shown) on the inside thereof. Rotation of the collar  38  by the user of the device allows the user to select which active electrodes  14 A to  14 D are energised. For example, rotation of the collar  38  to a first position sets the contacts such that every electrode  14 A to  14 D is energised, such that the anti-coring system is deactivated and the device cuts tissue around the entire circumference of the tube  8 . Alternatively, rotating the collar  38  to a second position sets the contacts such that one electrode  14 A is not energised, whereas each of the remaining electrodes  14 B,  14 C and  14 D is energised. This inhibits cutting in the region of the electrode  14 A, and provides the anti-coring action described previously. Rotating the collar  38  to a further position selects a different electrode  14 B which is not energised, whereas each of the other electrodes  14 A,  14 C and  14 D is energised. In this way, the orientation of the tube  8  can be varied, and yet an active electrode can be selected not to be energised, such that orientation of the anti-coring action remains constant with respect to the tissue being treated. 
         [0037]    In an alternative arrangement, rotation of the collar  38  varies the number of active electrodes  14 A to  14 D that are not energised, rather than the position of the active electrode that is not energised. In this way, the user can vary the extent of the anti-coring action provided by the morcellating device  1 . 
         [0038]      FIG. 6  shows an alternative embodiment in which a collar  38  is also provided, but in this embodiment the rotation of the collar causes a corresponding rotation of the electrosurgical assembly  13  at the distal end of the tube  8 . The electrosurgical assembly  13  comprises a return electrode  16  which extends completely around the circumference of the tube  8 , and an active electrode  14  which is interrupted in the region B by means of an insulated section  30 . The electrosurgical assembly  13  is connected to the collar  38  by means of a sleeve  39 , such that rotation of the collar causes a corresponding rotation of the electrosurgical assembly  13 . The insulated section  30  can, therefore, be rotated between different angular positions, hence varying the angular position of the anti-coring effect described previously. 
         [0039]      FIGS. 7 to 9  show a different arrangement in which both the active electrode  14  and the return electrode  16  extend completely around the circumference of the tube  8  at the distal end thereof. An electrically-insulating mask  41  is provided in a first circumferential region of the tube  8 , so as to prevent the active electrode  14  from engaging tissue in that region. The mask  41  prevents tissue cutting in that region, and provides the anti-coring effect described previously. The mask  41  is typically an injection moulded polymer component, such as the polymer-nylon material “Zytel”. In one arrangement, the mask  41  is disposed within a compartment  42  at the end of the tube  8 , and can be selectively advanced and retracted by the operation of an actuating mechanism (not shown). When the mask  41  is advanced, it moves into a position obscuring the active electrode  14  in the first circumferential region, thereby providing the anti-coring effect described previously. When the mask  41  is retracted into the compartment  42 , it allows the active electrode  14  to cut tissue around its entire circumference. 
         [0040]    In an alternative arrangement, the mask  41  can be selectively attached or detached from the tube  8 , depending on whether the anti-coring effect is desired by the user of the morcellating device  1 , or whether maximum cutting effectiveness is required. 
         [0041]    It will he appreciated by those skilled in the art that many minor modifications and alternative constructions can be envisaged, without departing from the scope of the present invention. For example, the tube  8  can be provided with a marker in alignment with the second circumferential region B, so as to highlight the position of that region to a user of the device. Providing an effective electrosurgical tissue-cutting assembly, in which a circumferential region of the cutting area is selectively inhibited, promotes the instrument to perform a peeling action on the tissue, and restricts the ability of the instrument to become buried in the tissue in a coring manoeuvre.