Patent Publication Number: US-2011066157-A1

Title: Treatment tool

Description:
This application is a Continuation of International Application No. PCT/JP2009/071453, filed on Dec. 24, 2009, claiming priority based on Japanese Patent Application No. 2008-327379, filed on Dec. 24, 2008, the content of which is incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a treatment tool which is inserted through an endoscope or the like for performing various kinds of treatment on a tissue in a body cavity. 
     Priority is claimed on Japanese Patent Application No. 2008-327379 filed on Dec. 24, 2008, the contents of which are incorporated herein by reference. 
     BACKGROUND ART 
     Conventionally, treatment tools involving endoscopic insertion into a body cavity for performing various kinds of treatment on a tissue in the body cavity is known. Generally, these treatment tools have an elongated insertion portion having flexibility, and a treatment part which performs treatment is provided at the tip of an insertion portion inserted into a body. An operation part for operating the treatment part is provided at the proximal side of the insertion portion which is pulled out from the proximal side of an endoscope or the like through which the treatment tool is inserted. The treatment part and the operation part are connected together by a connecting member, such as a wire or a rod. 
     Although the shape or construction of the treatment part may vary greatly depending on the procedures to be performed by the treatment tool, a treatment tool including a treatment part with a hollow needle tube with a sharp tip is known as an example (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2008-173313). Such a treatment tool is used, for example, when a medicinal solution is injected into a tissue, or a saline solution or the like is injected into a tissue to make the tissue swell. 
     In the treatment tool described in Japanese Unexamined Patent Application, First Publication No. 2008-173313, a tube which supplies fluids, such as a medicinal solution, to a proximal end of the needle tube is attached, and is inserted into an external tubular sheath which constitutes an insertion portion. The needle tube is integrally fixed to the tube via a coupling member made of metal or the like. Since a comparatively large force acts on the needle tube when the needle tube is inserted into a tissue, it is necessary to reliably fix the needle tube and the coupling member. In practice, both the needle tube and the coupling member are often fixed, for example, by caulking the coupling member as this is simple and easy. In addition, the coupling member may be fixed not only by caulking but also by brazing. 
     In addition, a fixing method of a coupling member and a needle tube is not limited to caulking and brazing, but other fixing methods may be employed. In the following description, a case where fixing is performed by caulking and brazing is described as an example. 
     SUMMARY OF THE INVENTION 
     A first aspect of the invention is a treatment tool endoscopically inserted into a body cavity. The treatment tool includes a treatment part for performing a treatment within the body cavity; a connecting member connected to a proximal end of the treatment part; a sheath through which the treatment part and the connecting member are inserted so as to be able to advance or retreat in an axis direction; an operation part which is connected to the connecting member and extends and retracts the connecting member with respect to the sheath; and a coupling member, which is formed in a tubular shape, provided with a large diameter portion with substantially the same external diameter as the internal diameter of the sheath and a fixing portion with an external diameter smaller than that of the large diameter portion, and fixed to at least any one of the connecting member and the treatment part. The connecting member or the treatment part is inserted to the fixing portion and fixed to the fixing portion in a state where the diameter of the fixing portion is smaller than that of the large diameter portion, and the large diameter portion prevents the treatment part and the connecting member from wobbling in a direction separating from the axis of the sheath within the sheath. 
     In accordance with a second aspect of the present invention, the treatment part and the connecting member may be integrally connected by the coupling member. 
     In accordance with a third aspect of the present invention, the sheath may have an abutting portion which is formed so that the treatment part can pass therethrough and the coupling member cannot pass therethrough. 
     In accordance with a fourth aspect of the present invention, the abutting portion may be formed by reducing the internal diameter of the tip of the sheath. 
     In accordance with a fifth aspect of the present invention, the large diameter portion may have a first large diameter portion at the distal side, and a second large diameter portion located closer to the proximal side than the first large diameter portion, and the fixing portion may be provided between the first large diameter portion and the second large diameter portion. 
     In accordance with a sixth aspect of the present invention, the treatment part may be a hollow needle tube, and the connecting member may be formed in the shape of a tube capable of supplying a fluid to the needle tube. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view showing a treatment tool of a first embodiment of the invention. 
         FIG. 2  is an enlarged sectional view in the vicinity of the tip of the treatment tool. 
         FIG. 3  is a view showing a coupling member of the treatment tool. 
         FIG. 4  is a view showing the process of fixing the coupling member and needle tube of the treatment tool integrally. 
         FIG. 5  is a view showing the coupling member and needle tube after fixing. 
         FIG. 6  is a sectional view showing an operation part of the treatment tool. 
         FIG. 7  is a sectional view in a line A-A of  FIG. 6 . 
         FIG. 8  is a sectional view showing the operation part when a treatment part is housed in a sheath. 
         FIG. 9  is an enlarged sectional view in the vicinity of the tip of a treatment tool of a second embodiment of the invention. 
         FIG. 10  is an enlarged sectional view in the vicinity of the tip of a treatment tool of a modification of the invention. 
         FIG. 11  is an enlarged sectional view around an operation part of the treatment tool of the modification of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     A treatment tool of a first embodiment of the invention will be described with reference to  FIGS. 1 to 8 .  FIG. 1  is a view showing the treatment tool  1  of the present embodiment. The treatment tool  1  is constructed such that a hollow needle tube  5 , which becomes a treatment part  4 , is provided at the tip of an elongated sheath  3 , which becomes an insertion portion  2  inserted into a body cavity, so as to freely project or recede from the tip. An operation part  6  for performing the projecting/receding operation of the needle tube  5  is attached to a proximal end of the sheath  3 . 
       FIG. 2  is an enlarged sectional view showing the distal side of the treatment tool  1 . The sheath  3  is formed using resin or the like so as to have flexibility, and an opening  3 A at the distal side of the sheath has a reduced opening diameter to such a degree that the needle tube  5  can be inserted therethrough, and a coupling member which will be described later cannot be inserted therethrough. An end face  3 B in the opening  3 A functions as an abutting portion  7  which regulates the projecting length of the needle tube  5  from the sheath  3  to a predetermined length. 
     The proximal side of the needle tube  5  is connected to a tube (connecting member)  9  made of resin or the like via a tubular coupling member (sliding member)  8  made of metal. A proximal end of the tube  9  is connected to the operation part  6  and transmits the projecting/receding operation of the needle tube  5  in the operation part  6  to the needle tube  5 , and also functions as a supply means which supplies fluids, such as a medicinal solution and air, to the needle tube  5 . The needle tube  5 , the coupling member  8 , and the tube  9  are inserted through the sheath  3  so as to be able to extend and retract in an axis direction. 
       FIG. 3  is a view showing the coupling member  8 . The coupling member  8  is a substantially cylindrical member formed from a plastically deformable material, such as metal. The coupling member  8  has a large diameter portion  8 A at the distal side with the largest external diameter, a fixing portion  8 B provided at the proximal side of the large diameter portion  8 A, and a connecting portion  8 C provided at the proximal side of the fixing portion  8 B. The external diameter of the large diameter portion  8 A is set to be equal to or slightly smaller than the internal diameter of the sheath  3 , i.e., substantially equal to the internal diameter of the sheath  3 . Accordingly, the coupling member  8  having the large diameter portion  8 A, as shown in  FIG. 2 , is not able to pass through the opening  3 A of the tip of the sheath  3 , and abuts the abutting portion  7 . 
     As shown in  FIG. 4 , the needle tube  5  is inserted through the coupling member  8 , and the fixing portion  8 B is pressed from the direction of the arrow, and is plastically deformed. That is, the needle tube  5  and the coupling member  8  are integrally fixed as the fixing portion  8 B is caulked. 
     In addition, the pressing direction shown by the arrow in  FIG. 4  is an example, and the direction is not particularly limited. 
     In addition, the needle tube  5  and the coupling member  8  may be integrally fixed by not only caulking but also brazing. Although not shown, in the case of brazing, a through hole penetrating in the radial direction to the needle tube is formed in a portion of the fixing portion of the coupling member. As brazing filler metal which flows in from this through hole fills and solidifies a gap between the needle tube and the coupling member, the needle tube and the coupling member are integrally fixed. 
     Additionally, in the case of brazing, stainless steel and steel suitable for brazing among metals may be used for the material of the coupling member. 
     Although the fixing portion  8 B before caulking is substantially cylindrical, the cross-section of the fixing portion orthogonal to the axis direction becomes substantially elliptical due to the caulking. As a result, as shown in  FIG. 5 , the radial dimension of the fixing portion  8 B increases partially. The external diameter before the caulking of the fixing portion  8 B is set to be smaller than the external diameter of the large diameter portion  8 A, and the pressing force is adjusted to perform caulking so that the maximum external diameter D 1  of the fixing portion  8 B at this time becomes less than or equal to the external diameter D 2  of the large diameter portion  8 A. 
     The needle tube  5  and the coupling member  8  which have been integrally fixed, as shown in  FIG. 2 , are integrally fixed with an adhesive or the like after the connecting portion  8 C is inserted into the distal side of the tube  9 . In this way, the needle tube  5 , the coupling member  8 , and the tube  9  are integrated and connected together so as to be able to extend and retract with respect to the sheath  3 . 
     As shown in  FIGS. 1 and 6 , the operation part  6  has an operation part body  21  to which the proximal end of the sheath  3  is connected and fixed, and an operation tube  22  which is extendably and retractably inserted into the operation part body  21 . The operation part body  21  is formed with a hole  25  which penetrates in the longitudinal direction (axial direction), and the tube  9  is inserted into the hole  25 . The diameter of the hole  25  is made larger at the proximal side than at the distal side, and a tube portion  26  of the operation tube  22  is inserted into the diameter-enlarged hole  25 A. As shown in  FIG. 7 , the diameter-enlarged hole  25 A is formed with two key grooves  27  which extend in the longitudinal direction. The number and arrangement of the key grooves  27  are not limited to those illustrated. 
     Moreover, a first diameter-enlarged portion  31  and a second diameter-enlarged portion  32  of which the internal diameter is enlarged are respectively formed at the distal side and proximal side of the diameter-enlarged hole  25 A so as to avoid the key grooves  27 , respectively. A pair of the first diameter-enlarged portion  31  at the distal side is symmetrically provided across the hole  25 A, and includes holes  33  which are bored toward the diameter-enlarged hole  25 A from the outer periphery of the operation part body  21 . 
     Each hole  33  is bored obliquely with respect to the axis of the operation part body  21  so that an opening at the inner circumferential side is formed at the proximal side with respect to an opening at the outer circumferential side. Thereby, the wall surface of the hole  33  at the distal side forms an inclined surface  33 A which makes an acute angle with respect to the axis. The wall surface of the hole  33  at the proximal side forms an inclined surface  33 B which makes an obtuse angle with respect to the axis. 
     A pair of the second diameter-enlarged portion  32  at the proximal side is also symmetrically provided across the hole  25 A, and includes holes  35  which are bored toward the diameter-enlarged hole  25 A from the outer periphery of the operation part body  21 . Each hole  35  is bored obliquely with respect to the axis of the operation part body  21  so that an opening at the inner circumferential side is formed at the distal side with respect to an opening at the outer circumferential side. Thereby, the wall surface of the hole  35  at the distal side forms an inclined surface  35 A which makes an obtuse angle with respect to the axis. The wall surface of the hole  35  at the proximal side forms an inclined surface  35 B which makes an acute angle with respect to the axis. 
     In the operation tube  22 , a mouthpiece  41  is integrally formed at a proximal end of the tube portion  26  which can be inserted into the diameter-enlarged hole  25 A. The operation tube  22  is provided with a through hole  42  which leads to the tip of the tube portion  26  from the mouthpiece  41 . A hard pipe  43  is press-fitted into and fixed to a distal end of the through hole  42 . The pipe  43  advances into the hole  25  of the operation part body  21 , and is connected to the tube  9 . 
     As shown in  FIG. 7 , two keys  44  are provided at the outer periphery of the tube portion  26  so as to protrude therefrom. The keys  44  are formed in accordance with the formation positions of the key grooves  27  at the operation part body  21 . The relative rotation of the keys and the key grooves around the axis is prevented by inserting the operation tube  22  into the operation part body  21  so that the keys  44  engage the key grooves  27 . 
     As shown in  FIG. 6 , a pair of locking portions  51  is formed at the tip of the operation tube  22  so as to pinch the pipe  43 . The pair of locking portions  51  is portions which are formed so as to be elastically deformable by making a slit in the tip of the tube portion  26 , and has protruding portions  52  provided on the radial outside at distal ends which become free ends. Each protruding portion  52  has an inclined surface  52 A of which the tip is obliquely cut toward the center. The proximal side of the protruding portion  52  has become a flat surface  52 B substantially along the radial direction. In a state where an external force does not act, the distance between external surfaces  52 C of the pair of protruding portions is greater than the diameter of the hole  25 A. 
     The locking portions  51  and the diameter-enlarged portions  31  and  32  are formed so that the needle tube  5  projects from the sheath  3 , and is located at a working position where the needle tube can be inserted into a tissue, when the protruding portions  52  of the locking portions  51  are made to coincide with first diameter-enlarged portions  31 . Furthermore, the locking portions  51  and the diameter-enlarged portions  31  and  32  are formed so that the needle tube  5  is located at a housed position where the needle tube  5  is completely pulled into the sheath  3 , when the protruding portions  52  of the locking portions  51  are made to coincide with the second diameter-enlarged portions  32 . 
     The operation when the treatment tool  1  constructed as described above is used will be described below. 
     First, a user inserts an endoscope (not shown) through a patient&#39;s mouth or the like, and moves the tip of the endoscope to a part to be treated while confirming with an imaging device of the endoscope. 
     Next, the treatment tool  1  is inserted through a working channel of the endoscope, and the tip of the sheath  3  of the insertion portion  2  is endoscopically introduced into a body cavity. As shown in  FIG. 8 , as an initial state of the operation part  6 , the protruding portions  52  of the locking portions  51  are locked to the second diameter-enlarged portions  32 , and the needle tube  5  is housed in the sheath  3 . Since the flat surfaces  52 B of the protruding portions  52  abut on the inclined surfaces  35 B of the second diameter-enlarged portions  32  at this position, it is no longer possible to pull out the operation tube  22 . 
     When the needle tube  5  is projected from the sheath  3 , the user holds a mouthpiece  41  and pushes the operation tube  22  into the operation part body  21 . By means of the inclined surfaces  35 A of the second diameter-enlarged portions  32  at the distal side, the pair of locking portions  51  is pressed in a direction in which the locking portions are closed (radially inward of the tube portion  26 ), and the distance between the external surfaces  52 C of the protruding portions  52  is decreased less than or equal to the diameter of the hole  25 A. As a result, the pair of locking portions  51  can be advanced into the hole  25 A. When the operation tube  22  is pushed in, the needle tube  5  coupled with the operation tube  22  via the pipe  43  or the tube  9  advances with respect to the sheath  3 . 
     Since the diameter of the hole  25 A are substantially constant to the first diameter-enlarged portions  31 , the operation tube  22  advances smoothly, and the needle tube  5  begins to project from the sheath  3 . When the protruding portions  52  of the pair of locking portions  51  reach the first diameter-enlarged portions  31 , the pair of locking portions  51  return their original positions and separate from each other, and as shown in  FIG. 6 , the locking portions  51  are received in the first diameter-enlarged portions  31 . When the operation tube  22  is at this position, the needle tube  5  is projected from the sheath  3  at the distal side by a predetermined length. 
     Here, in a case where the operation tube  22  is intended to further advance, the inclined surfaces  52 A at the tips of the protruding portions  52  abut the inclined surfaces  33 A of the first diameter-enlarged portions  31 . Since the inclination direction of the inclined surfaces  33 A is a direction in which the inclined surfaces  33 A do not press the locking portions  51  in a diameter-reduced direction, but interfere with the locking portion, the operation tube  22  cannot be advanced any further. 
     On the other hand, when the operation tube  22  is intended to be pulled and retracted by a comparatively weak force, the surfaces  52 B of the protruding portions  52  at the proximal side interfere with the inclined surfaces  33 B of the first diameter-enlarged portions  31  by abutting thereto. That is, the locking portions  51  are locked to the first diameter-enlarged portions  31 , and the position of the needle tube  5  is locked. Accordingly, if a user pushes in the operation part body  21  to advance the whole treatment tool  1 , the needle tube  5  can be inserted into a tissue to be treated. 
     At this time, since the external diameter of the large diameter portion  8 A of the coupling member  8  integrally fixed to the needle tube  5  is set to be equal to or slightly smaller than the internal diameter of the sheath  3 , almost no gap exists between both the large diameter portion  8 A and the sheath  3 . Thereby, even if a force acts on the needle tube  5  at the time of procedure, such as insertion, the needle tube  5  does not wobble so as to separate from the axis of the sheath  3 , and the coupling member  8  smoothly slides inside the sheath  3 . 
     If the needle tube  5  has been inserted into a tissue, fluids, such as various liquids, such as a medicinal solution and a saline solution, various gases, such as air, or the like are delivered from a syringe (not shown) connected to the mouthpiece  41 . A supplied fluid is injected into the tissue from the needle tube  5  through the tube  9 . Thereby, various kinds of procedure, such as drug administration and tissue swelling, can be performed. 
     After the end of a treatment, a user retracts the treatment tool  1  to extract the needle tube  5  from the tissue. 
     When the needle tube  5  is housed into the sheath  3 , a user pulls the operation tube  22  with a stronger force than an acting force at the time of insertion, and retracts the operation tube  22  with respect to the operation part body  21 . The protruding portions  52  of the locking portions  51  are pressed by the inclined surfaces  33 B of the first diameter-enlarged portions  31 , and the pair of locking portions  51  is closed. This enables the operation tube  22  to retract. The engagement force between the protruding portions  52  and the inclined surfaces  33 B regulates unintended movement of the operation tube  22  when the needle tube  5  is inserted into a tissue, and the shape of the operation tube  22  is set so as to deform the pair of locking portions  51  when the mouthpiece  41  is manually pulled. 
     When the protruding portions  52  reach the second diameter-enlarged portions  32  in the process in which the operation tube  22  is retracted, the pair of locking portions  51  returns to its original position, and is caught in the operation part body  21 . When the locking portions  51  are stopped at this position, the needle tube  5  is completely housed in the sheath  3 . In addition, the inclined surfaces  35 B of the second diameter-enlarged portions  32  at the proximal side interfere with the locking portions  51  in a direction in which the operation tube  22  retracts, and prevents slip-off of the locking portions. Accordingly, the operation tube  22  is not caused to slip off by normal operation. 
     According to the treatment tool  1  of the present embodiment, in the coupling member  8 , the needle tube  5  and the coupling member  8  are firmly and integrally fixed by caulking the fixing portion  8 B with a smaller external diameter than the large diameter portion  8 A. In a fixed state, the maximum external diameter of the caulked fixing portion  8 B is set to be less than or equal to the external diameter of the large diameter portion  8 A. 
     Accordingly, since the external diameter of the coupling member  8  is always greatest at the large diameter portion  8 A which is not deformed even after caulking, almost no gap exists between the large diameter portion  8 A and the sheath  3  whose cross-sections in the radial direction are substantially true circles. Therefore, the coupling member  8  and the needle tube  5  slide smoothly without clattering within the sheath  3 , and do not wobble so that the needle tube  5  separates from the axis of the sheath  3 . As a result, the behavior of the needle tube  5  serving as the treatment part  4  can be consistently stabilized during procedure, and the procedure can be easily and reliably performed. 
     Additionally, in the coupling member  8 , the large diameter portion  8 A which specifies a maximum external diameter, and the fixing portion  8 B used for caulking fixing are formed in separate regions. Thus, the thickness of the fixing portion  8 B can be set to a wall thickness which is always optimal for caulking irrespective of the external diameter of the coupling member  8 . 
     Additionally, the diameter of the opening  3 A of the tip of the sheath  3  is set such that the coupling member  8  cannot pass therethrough. Thus, even if the operation part body  21  and the operation tube  22  are disengaged, unintended projection of the needle tube  5  can be prevented as the abutting portion  7  and the coupling member  8  abut each other. 
     Moreover, since the large diameter portion  8 A is provided at the distal side of the fixing portion  8 B, deformation of the fixing portion  8 B caused by caulking is not transmitted to the distal side of the coupling member  8 . Accordingly, in order to suppress clattering of the needle tube  5 , it is not necessary to take a longer axial dimension of the fixing portion  8 B, and the dimension, in the axis direction, of the region of the coupling member  8  closer to the distal side than the connecting portion  8 C can be made shorter than before, for example, can be made shorter to about 2 millimeters (mm). As a result, the hard length (the length of a region of which the flexibility is relatively lower than the sheath  3  or the tube  9 ) of the treatment tool  1  at the distal side can be made short to improve the insertion performance of the treatment tool  1 . 
     In addition, since two diameter-enlarged portions  31  and  32  are provided in the extending/retracting direction of the needle tube  5 , and the diameter-enlarged portions  31  and  32  are formed with a tapered face, it is possible to deform the protruding portions  52  of the operation tube  22  simply by extending or retracting the operation tube  22 . That is, operation becomes easy with a simple construction. Since the diameter-enlarged portions  31  and  32  are formed so as to correspond to a working position to which the needle tube  5  projects, and at the housed position where the needle tube  5  is completely housed in the sheath  3 , projecting/receding of the needle tube  5  can be controlled simply by moving the operation tube  22  to its locked position. 
     In an injection needle of a type in which a needle tube is fixed to a working position by pushing or screwing a mouthpiece into an operation part body as in a conventional technique, a large amount of force required for pushing-in or screwing-in ultimately becomes necessary. In contrast, in this treatment tool  1 , it is not ultimately necessary to apply a large amount of force, and thus, the operation is easy. Additionally, when the needle tube  5  is fixed to a working position, there is no shortage in the required amount of force. 
     Subsequently, a treatment tool of a second embodiment of the invention will be described with reference to  FIG. 8 . A difference between the treatment tool  61  of the present embodiment and the endoscopic treatment tool  1  of the above-described first embodiment is the shape of the coupling member. In addition, constituent elements common to those of the above-described treatment tool  1  will be designated by the same reference numerals, and the description thereof is omitted. 
       FIG. 9  is an enlarged sectional view in the vicinity of the tip of the treatment tool  61 . A coupling member  62  of the treatment tool  61  is provided with two large diameter portions  63  of a first large diameter portion  63 A at the distal side and a second large diameter portion  63 B adjacent to a connecting portion  64  connected to the tube  9 . A fixing portion  65  which is caulked in order to integrally fix the needle tube  5  and the coupling member  62  is provided between the first large diameter portion  63 A and the second large diameter portion  63 B. 
     According to the treatment tool  61  of the present embodiment, the coupling member  62  is provided with two large diameter portions of the first large diameter portion  63 A and the second large diameter portion  63 B. Thus, wobbling of the needle tube  5  in the above-described procedure can be more suitably prevented. 
     Additionally, since the fixing portion  65  is located so as to be pinched by the large diameter portions  63 A and  63 B, the deformation caused by the caulking of the fixing portion  65  does not extend in any axis direction of the coupling member  62 , and is limited to the fixing portion  65 . Accordingly, it is not necessary to consider the deformation and set the fixing portion to be long. Therefore, it is possible to shorten the coupling member  62  to make the hard length of the tip of the treatment tool  61  shorter. 
     Moreover, although the coupling member  62  of the present embodiment is provided with two large diameter portions, the two large diameter portions are easily formed simply by performing cutting or the like of an outer circumferential surface so that the fixing portion is formed in a tubular member which has the same external diameter before working as the large diameter portions. Accordingly, it is possible to manufacture the coupling member  62  through substantially the same process as that of the above-described coupling member  8 , and the manufacture does not become complicated. 
     Although the embodiments of the invention have been described hitherto, the technical scope of the invention is not limited to the above embodiments, but various modifications may be made without departing from the scope of the invention. 
     An example in which the abutting portion is provided at the tip of the sheath has been described in the above embodiments. Instead of this, however, the abutting portion may be formed at a position separated from the tip by a predetermined length, for example, by a method of press-fitting a ring-shaped member into the sheath. In this case, the large diameter portion may not necessarily be provided at the tip of the coupling member. 
     Additionally, the abutting portion is not necessarily formed over the whole circumferential direction so long as the treatment part can pass therethrough and the coupling member cannot pass therethrough. For example, the abutting portion may be formed so as to protrude partially from the inner wall of the sheath so that the internal diameter thereof is just partially reduced. 
     Moreover, an example in which the treatment part and the tube which is a connecting member are integrally coupled together via the coupling member has been described in the above embodiments. Instead of this, however, the treatment part and the connecting member may be coupled together by other methods, such as press-fitting, bonding, and welding, and a coupling member may be attached to either the treatment part or the connecting member, or both the treatment part and the connecting member as a stopper. Even in this way, it is possible to suppress wobbling of the treatment part or connecting member suitably. 
     Additionally, an example in which a coupling member functions as a stopper abutting on the abutting portion has been described in the above-described embodiments. However, a configuration in which the abutting portion is not provided in the sheath  3 , and the coupling member does not function as a stopper may be adopted like the treatment tool  71  of the modification shown in  FIG. 10 . 
     In the treatment tool  71 , a snare wire  72  is provided as a treatment part, and an operation wire  73  serving as a connecting member connects the snare wire  72  and an operation part (not shown). Ends of a snare wire  72  and an operation wire  73  are respectively inserted into both ends of a tubular coupling member  62 , and, as the fixing portion  65  is fixed by caulking and brazing, the snare wire  72  and the operation wire  73  are integrally connected. Even in this configuration, wobbling of the snare wire  72  and the operation wire  73  can be suitably suppressed. Additionally, in the case of the treatment tool which takes such a configuration, the coupling member can be projected further forward than the tip of the sheath. Thus, for example, it is also possible to use the coupling member as a marker for roughly locating the treatment part under X-ray illumination. 
     Moreover, as for the coupling member in the invention, a coupling member may be attached to the end of the operation wire  73 , serving as a connecting member, at the side of the operation part  82 , like the treatment tool  81  of the modification shown in  FIG. 11 . 
     In the treatment tool  81 , the dimension of a coupling member  83  in the axis direction is set to be long, and the coupling member  83  functions as a buckling preventing pipe of the operation wire  73 . The length, in the axis direction, of a second large diameter portion  83 B at the proximal side is longer than a first large diameter portion  83 A at the distal side. This makes it possible to suitably suppress wobbling of the operation wire  73  in the operation part body  84  of the operation part  82 . 
     In addition, in this operation part  82 , the operation wire  73  is connected to a slider  85  which is attached so as to be slidable in the axis direction of the operation part body  84 , and extending//retracting operation of the operation wire  73  via the slider  85  is possible. However, an aspect in which the operation wire  73  and the slider  85  are connected together is not particularly limited. For example, the coupling member  83  is fixed to the operation wire  73  by fixing, such as caulking or brazing of a fixing portion  83 C. However, the operation wire  73  may be directly connected to the slider  85  without being fixed to the coupling member  83 , or the operation wire  73  and the slider  85  may be integrally connected via the coupling member  83 . Moreover, both the operation wire  73  and the coupling member  83  may be connected to the slider  85 . 
     In addition, although an example of the treatment tool which has the needle tube and the snare wire as the treatment part has been described in the above-described embodiments, the treatment tool to which the invention can be applied is not limited to this. Accordingly, the structure of the invention can be applied to various treatment tools including not only the needle tube and the above-described snare wire, but also various kinds of structures for performing arbitrary procedures as the treatment part. 
     According to the treatment tool of the invention, a large gap does not exist between the large diameter portion and the sheath, and the treatment part or connecting member is suitably prevented from wobbling so as to separate from the axis during operation. 
     In accordance with the third aspect of the present invention, as the connecting member is extended with respect to the sheath until the coupling member abuts the abutting portion, the coupling member can function as a stopper, and the projecting amount control or positioning of the treatment part can be suitably performed. 
     In accordance with the fourth aspect of the present invention, the abutting portion can be easily formed in the sheath. 
     In accordance with the fifth aspect of the present invention, wobbling of the treatment part or connecting member can be further reduced, and the behavior of the treatment part or connecting member can be made more stable. 
     In accordance with the sixth aspect of the present invention, a fluid can be supplied in a state where the behavior of the needle tube is stable, and treatments, such as injection of a medicinal solution, tissue swelling, or the like, can be performed. 
     According to the treatment tool of the invention, it is possible to provide a construction in which wobbling does not easily occur in a direction in which the treatment part or the connecting member separates from the axis.