Patent Publication Number: US-2005131403-A1

Title: Polypectomy snare for specimen retrieval

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The field of the present invention relates to apparatuses and procedures for the removal of polyps and other tissues from inside the gastrointestinal tract during endoscopy procedures. Specifically, the invention described herein relates to an improved snare apparatus used to remove polyps from the colon during colonoscopy. More specifically, the present invention relates to a snare apparatus that is configured to facilitate the retrieval of a polyp which has been separated from the colon.  
      2. Background  
      Colonoscopy is an extremely important and prevalent medical procedure, especially in the field of colo-rectal cancer detection. At present, over five million colonoscopies are performed per year in the United States alone. An important aspect of the colonoscopy procedure is in the detection and removal of polyps, which are comprised of soft tissue matter, from the colon. Generally, about two thirds of the polyps found in the colon are adenematous and are considered to be pre-malignant. It is generally believed that the removal of these polyps can prevent cancer formation in the colon. Endoscopic inspection alone is usually not sufficient to determine whether a polyp is adenomatous or of another type, such as hyperplastic, that carries no malignant potential. Instead, medical specialists desire the polyp be sent to a laboratory where it can be microscopically examined to determine whether it is malignant or benign. Generally speaking, therefore, all polyps should be removed from the patient when detected during colonoscopy.  
      The most commonly used technique for removing polyps involves the insertion of a catheter instrument, primarily biopsy forceps or polypectomy snare, through the biopsy channel of the colonoscope. The polypectomy snare has a control handle operatively connected to one end of a wire that is slidably disposed inside a sheath. The opposite end of the wire has a wire loop portion that is configured to collapse to a closed condition when contracted inside the tip of the sheath by operation of the control handle and expand to an open condition when extended out of the sheath. To remove a polyp, the opened wire loop is placed around the polyp and then gradually closed to, in effect, lasso it. When the wire loop closely surrounds the base of the polyp, an electric current is sent through the wire to cauterize the polyp, which dessicates the tissue to allow the wire to more easily cut through the base of the polyp. Utilizing the control handle, the physician gradually closes the wire loop around the polyp by withdrawing the wire back into the plastic sheath. By the time the polyp is completely cut, the tip of the wire loop is usually completely inside the plastic sheath, with the tip of the cut polyp about one centimeter above the tip of the sheath. Once the polyp is severed from the mucosa of the colon, it needs to be retrieved and placed in a container to be submitted to a laboratory for microscopic examination in order to determine its type and the presence of any malignant or suspicious cells.  
      Small polyps, such as those that are approximately eight millimeter or less in size, account for the great majority of colonic polyps. These small polyps are small enough to be retrieved by suctioning through the biopsy-suction channel of the colonoscope into a receptacle container, and then into a formalin bottle. The easiest way for retrieval is when the polyp adheres to the tip of the plastic sheath of the snare, in which case it can be simply pulled into the channel and quickly retrieved therefrom. However, in a large minority of cases, the separated polyp does not adhere to the tip of the sheath of the snare, but instead falls inside the colon. While any fallen polyps can usually be found and suctioned through the endoscope, sometimes the searching and the suctioning process can be long and arduous, particularly when a small polyp falls into a difficult to see or reach place. It is not uncommon, however, that the polyp is lost and cannot be retrieved, which is a highly undesirable situation.  
      The tip of the presently available plastic sheath portion of polypectomy snares is smooth and beveled, with a generally planar surface. The bevel facilitates insertion of the snare through the rubber valve at the top of the biopsy-suction channel. When the directional orientation of the beveled tip is favorable, namely the cut portion of the bevel is facing upward, the bevel can help keep a removed polyp on the tip of the sheath. However, the directional orientation of the sheath is generally a result of happenstance, as the orientation cannot be easily controlled while inside the colon. Not infrequently, the polyp falls off, especially when the bevel faces downward. Various retrieval devices are available to help remove larger polyps that cannot go through the suction channel of the colonoscope. These include net or basket devices, such as the Roth basket, the Nakao snare and others.  
      Although presently available devices are adapted for the retrieval of polyps from inside the colon, they are generally only effectively used for retrieval of larger polyps. In addition, the presently available devices typically require removal of the poypectomy snare used to cut the polyp from the colonoscope prior to insertion of the retrieval device. Unfortunately, this can make the retrieval of a cut polyp more difficult, as the position of the polyp can become “lost” during the exchange of tools. What is needed, therefore, is an plypectomy snare that is particularly configured for improved retrieval of polyps, particularly small polyps, from inside the colon during colonoscopic procedures so that a greater percentage of polyps can be analyzed by a laboratory to determine if they are benign or malignant. Such an improved polypectomy snare should more easily retrieve polyps cut from the colonic wall to prevent loss of the polyp inside the colon. Ideally, such an polypectomy snare will minimize the amount of labor and time associated with a colonoscopy.  
     SUMMARY OF THE INVENTION  
      The polypectomy snare for specimen retrieval of the present invention provides the benefits and solves the problems identified above. That is to say, the present invention discloses an improved polypectomy snare that is adapted to cause the severed polyp to adhere to the tip of the sheath of the snare without regard to orientation of the snare inside the colon. The improved polypectomy snare is, therefore, one which will cause the severed polyp to predictably adhere to its tip so as to substantially improve the ability of the physician to recover small polyps. To the best of the inventor&#39;s knowledge, this type of polyp retrieving device has not been described before. The polypectomy snare of the present invention simplifies retrieval of cut polyps during endoscopic procedures and reduces the labor required for those procedures and, therefore, the likely discomfort of the patient.  
      In one embodiment of the present invention, the polypectomy snare for specimen retrieval comprises a control handle and longitudinal wire component comprised of an outer sheath and a wire member slidably disposed in the outer sheath. The proximal end of the wire member is operatively connected to the control handle and the distal end of the outer sheath has a tip. The tip has a non-planar tip surface that is shaped and configured to facilitate attachment of the polyp to the polypectomy snare after cutting the polyp from the inside of the organ (i.e., the colon). The tip has one or more spikes extending outwardly from the outer sheath, preferably a plurality of such spikes. The spikes can be made integral with the outer sheath, integral with the tip, attached to a planar tip surface at the distal end of the outer sheath or attached to a cap member that attaches to the outer sheath. In a preferred configuration, the plurality of spikes provide a tip surface that is generally saw-toothed shaped.  
      Accordingly, the primary objective of the present invention is to provide an improved polypectomy snare for specimen retrieval for use during colonoscopies and other endoscopic procedures that has the features generally described above and more specifically described below in the detailed description.  
      It is also an important objective of the present invention to provide a polypectomy snare for specimen retrieval that can be utilized to effectively retrieve small polyps removed from inside the colon or other organ.  
      It is also an important objective of the present invention to provide a polypectomy snare for specimen retrieval that comprises an outer sheath having a modified tip portion to improve the likelihood that a small polyp will adhere or attach to the sheath for removal of the polyps from the colon or other organ.  
      It is also an important objective of the present invention to provide a polypectomy snare for specimen retrieval that utilizes an outer sheath having a tip portion configured with one or more spikes.  
      The above and other objectives of the present invention are explained in greater detail by reference to the attached figures and description of the preferred embodiment which follows. As set forth herein, the present invention resides in the novel features of form, construction, mode of operation and combination of parts presently described and understood by the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings which illustrate the best modes presently contemplated for carrying out the present invention:  
       FIG. 1  is a top view of a presently available polypectomy snare showing the wire loop portion extended beyond the tip of the sheath;  
       FIG. 2  is a top view of an improved polypectomy snare for specimen removal of the present invention showing the wire loop portion retracted inside the modified tip of the sheath;  
       FIG. 3  is an isolated side view of the tip portion of the improved polypectomy snare of  FIG. 2 ;  
       FIG. 4  is an isolated side view of an alternative tip portion of the improved polypectomy snare of the present invention;  
       FIG. 5  is an isolated side view of an alternative tip portion of the improved polypectomy snare of the present invention; and  
       FIG. 6  is an isolated side view of an alternative tip portion of the improved polypectomy snare of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      With reference to the figures where like elements have been given like numerical designations to facilitate the reader&#39;s understanding of the present invention, and particularly with reference to the embodiments of the improved polypectomy snare for specimen retrieval of the present invention, identified as numeral  10  in  FIG. 2 , the preferred embodiments of the present invention are set forth below. The enclosed figures and drawings are merely illustrative of the preferred embodiments and represent several different ways of configuring the present invention. Although specific components, materials, configurations and uses of the present invention are illustrated and set forth in this disclosure, it should be understood that a number of variations to the components and to the configuration of those components described herein and in the accompanying figures can be made without changing the scope and function of the invention set forth herein.  
      The prior art polypectomy snare, shown as  12  in  FIG. 1 , comprises a control handle  14  operatively connected to a wire component  16 , which is sized and configured to fit within the biopsy channel of the typical endoscope, such as a colonoscope used for colonoscopies. In referring to the opposite ends of the improved polypectomy snare  10  or prior art polypectomy snare  12 , the “proximal end” refers to that part of the polypectomy snare  10 / 12  or wire component  16  that is closest to control handle  14  and the “distal end” refers to that part of the snare  10 / 12  or wire component  16  farthest from control handle  14 . As known to those skilled in the art, the typical control handle  14  comprises a thumb component  18  and a finger component  20  that is slidably disposed on handle body  22 . Wire component  16  comprises a wire member  24  operatively connected at the proximal end  26  of wire component  16  to finger component  20  and slidably disposed in an outer sheath  28 , typically made out of a plastic material, such that wire member  24  is generally free to move in the direction of the longitudinal axis of sheath  28 . The distal end  30  of wire member  24  comprises a collapsible wire loop  32  that is configured to be extended past tip portion  34  of outer sheath  28  and retracted inside sheath  28  by the sliding operation of finger component  20  of handle  12 . To remove a polyp, the opened wire loop  32  is placed around the polyp and then wire member  24  is gradually retracted to close wire loop  32  around the polyp. When wire loop  32  closely surrounds the base of the polyp, an electric current is sent through wire member  24 , via an electrical connection with electrical connector  36 , to cauterize the polyp. The electrical current dessicates the polyp tissue to allow wire member  24  to more easily cut through the base of the polyp. Utilizing control handle  12 , the physician gradually closes wire loop  32  around the polyp by withdrawing wire member  24  back into outer sheath  28 , thereby cutting the polyp from the organ (i.e., the colon).  
      As shown in  FIG. 1 , tip surface  38  of tip  34  of the presently available outer sheath  28  of polypectomy snare  12  is generally configured to be smooth and beveled, with a substantially planar cut across sheath  28 . The beveled configuration of tip  34  facilitates insertion of tip  34  through a rubber valve located on the endoscope at or near the top of the endoscope&#39;s biopsy-suction channel. As stated above, when the directional orientation of the bevel of tip surface  38  is favorable, namely facing upward, the bevel can help keep a removed polyp on tip  34  of sheath  28 . However, as known to those skilled in the art, the directional orientation of sheath  28  is generally a result of happenstance, as the orientation cannot be easily controlled while inside sheath  28  or the colon. Not infrequently, the cut polyp falls off of the smooth, beveled tip surface  38 , especially when the bevel portion of tip  34  faces downward. Because of the need for microscopic examination of the polyp to determine whether it is benign or malignant, when the polyp drops off of sheath  28  the physician will usually go to some effort, occasionally significant, to retrieve the polyp.  
      The polypectomy snare  10  of the present invention is configured to improve the ability of retrieving a cut polyp, shown as  40  in  FIG. 2 , without the need to resort to additional effort or equipment. As shown in  FIG. 2 , tip  34  of sheath  28  is shaped and configured to provide a non-smooth, non-planar tip surface  38  that is more beneficial for holding onto a cut polyp  40  that comes in contact therewith. In a preferred embodiment, as shown in  FIGS. 2 through 6 , tip surface  38  comprises one or more spikes or barb-like members  42  that extend beyond tip  34  of sheath  28 . In the preferred embodiment, spikes  42  have a sharp or pointed distal end  44  that is suitable for engaging polyp  40 . Tip surface  38  can be configured to comprise a barbed, saw-toothed, spiked or jagged surface (for ease of discussion, these and equivalent non-smooth surfaces are referred to as spiked, having one or more spikes  42 ). As set forth below, the sharp or pointed end  44  of spikes  42  will stick into polyp  40  and the troughs  46  between ends  44  will help trap and grasp polyp  40 . As known to those skilled in the art, spikes  42  can comprise a reverse portion that points generally in the direction of control handle  14  to better engage and hold onto polyp  40 . As also known to those skilled in the art, it is preferred that the spikes  42  be relatively short so as to not extend too far beyond tip surface  38  so that they will be less likely to penetrate the colon, even if they are inadvertently directed into the colonic wall.  
      In one configuration, shown in  FIGS. 2 and 3 , the improved snare  10  comprises a plurality of individual spikes  42  attached to and extending outwardly from tip surface  38  to form a non-planar tip  34  that is more suitable for retrieving polyp  40  than the smooth, generally planar tip surface  38  of the prior art snare  12 . Depending on the materials used for outer sheath  28  and spikes  42 , attachment of spikes  42  to tip surface  38  can be achieved by adhesives, various bonding techniques or a physical interconnection between spikes  42  and tip surface  38 . Those skilled in the art will recognize that other mechanisms for attaching individual spikes  42  to tip surface  38  may also be applicable. Spikes  42  can be made out of the same material as sheath  28 , typically a polyethylene or other plastic material, or made out of a non-plastic material. Once attached, spikes  42  form a non-planar tip surface  38  having spike ends  44  suitable for attaching to a cut polyp  40  to avoid loss thereof. It is preferred that spikes  42  be located around the entire circumference of tip surface  38  so that the orientation of wire component  16  in the colon is not important.  
      In another configuration, shown in  FIG. 4 , the improved snare  10  comprises a cap member  48  that is configured to be placed over tip  34  of an existing snare  12  and provide a tip surface  38  having one or more spikes  42  thereon. As shown in this figure, cap member  48  can be a molded component that is configured with a first end  50  that can be placed over the smooth tip  34  of the conventional snare  12  (shown with a straight cut edge) and have spikes  42  extending outwardly from the opposite second end  52 , creating an improved snare  10  of the present invention. Cap member  48  can be made out of the same material as sheath  28 , typically a polyethylene or other plastic material. First end  50  of cap member  48  can have an interior that is slightly larger than the exterior of tip  34  of snare  12  so that it will tightly fit over tip  34 . Cap member  48  can be bonded to tip  34  utilizing adhesives or other materials or joining methods suitable for sheath  28  and cap member  48 . In a preferred embodiment, the cap member  48  is sized and configured to attach to the tip surface  38  of tip  34  and provide a snare  10  having a smooth transition between sheath  28  and cap member  48  on tip  34 . Cap member  48  can be configured to fit over a sheath  28  having a beveled tip  34  or a non-beveled or straight cut tip  34 . Whether a straight or bevel cut is provided for cap member  48 , it is preferred that spikes  42  be located around the entire circumference of cap member  48  so that the orientation of wire component  16  in the colon is not important.  
      A preferred embodiment, at least for new polypectomy snares, is for spikes  42  of tip  34  to be integral with sheath  28 , as shown in  FIGS. 5 and 6 . This configuration can be achieved by cutting the tip end of sheath  28  with a spiked, saw-toothed, spiked or jagged cut to obtain a plurality of spikes  42  extending outwardly from tip surface  38  or by using a manufacturing process for sheath  28  (i.e., extrusion) that results in a plurality of spikes  42  extending outwardly from tip surface  38  in a generally saw-toothed configuration. An integral configuration avoids the additional cost and manufacturing steps associated with attaching individual spikes  42  ( FIG. 3 ) or cap member  48  ( FIG. 4 ) to the end of sheath  28 . As such, this configuration should be somewhat less expensive to manufacture. In addition, an integral tip  34  has the advantage of not providing a potential source of problems, such as those associated with the unintended separation of cap member  48  from sheath  28 . Whether a straight or bevel cut is provided for tip  34 , it is preferred that spikes  42  be located around the entire circumference of tip surface  38  so that the orientation of wire component  16  in the colon is not important.  
      As shown in  FIGS. 4 and 6  and discussed above, tip  34  of sheath  28  can be a straight edge cut, as opposed to the standard beveled cut shown in  FIGS. 2, 3  and  5 . In either configuration, polypectomy snare  10  having a plurality of spikes  42  on tip  34  may be more difficult to insert through the rubber inlet valve leading into the biopsy-suction channel of the endoscope. If spikes  42  do make it more difficult, the physician can overcome this problem by pushing the distal end of wire loop  32  slightly out of tip  34  beyond spike ends  44  to serve as the leading end of wire component  16 . This can be accomplished by slightly moving the finger component  20  of handle  14  slightly forward. To facilitate this operation, handle  14  can be modified to include a mark thereon for valve insertion and/or be made to “click” at the proper insertion point.  
      In use, wire component  16  of improved polypectomy snare  10  is inserted into the endoscope inlet valve for the biopsy-suction channel and directed to the distal end of the endoscope and the polyp  40  in the same manner as the presently available polypectomy snare  12 . Upon approaching polyp  40 , wire loop  32  is pushed out of sheath  28  to lasso the polyp  40 . A portion of tip  34  will be in contact with the base of polyp  40  as the wire loop  32  is retracted against the opposite side of polyp  40 . Because spikes  42  are around the circumference of tip surface  38 , a least some portion of the spikes  42  will be engaged with the polyp when it is cut from the colonic wall. Because spike ends  44  are sharp or pointed, the soft tissue of polyp  40  will attach to spikes  42 , allowing much improved retention of polyp  40  for retrieval from inside the colon. Reducing or eliminating the need to search for and separately retrieve a polyp will reduce the time, effort and discomfort associated with a colonoscopy. While the polypectomy snare  10  of the present invention is most applicable to colonoscopy, it is also applicable to other types of endoscopy procedures, such as gastroscopy and the like.  
      While there are shown and described herein certain specific alternative forms of the invention, it will be readily apparent to those skilled in the art that the invention is not so limited, but is susceptible to various modifications and rearrangements in design and materials without departing from the spirit and scope of the invention. In particular, it should be noted that the present invention is subject to modification with regard to the dimensional relationships set forth herein and modifications in assembly, materials, size, shape and use.