Patent Publication Number: US-2023136593-A1

Title: Treatment tool for endoscope

Description:
RELATED APPLICATION DATA 
     The present disclosure relates to a treatment tool for an endoscope. This application claims benefit from U.S. Patent Provisional Application No. 63/273,166, filed Oct. 29, 2021, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The disclosure relates to an endoscope treatment tool. 
     BACKGROUND 
     In the related art, in an endoscopic treatment such as endoscopic submucosal dissection (ESD) or the like, a treatment tool for an endoscope used in incision or dissecting such as a high frequency knife, or the like a treatment tool for an endoscope used in local injection, a treatment tool for an endoscope used in hemostasis, or the like, is used. 
     Chinese Unexamined Patent Application, First Publication No. 111202485A and Japanese Translation of PCT International Application Publication No. 2012-523863 disclose treatment tools for endoscopes capable of performing incision treatment and local injection treatment of a tissue. 
     In endoscopic treatment such as ESD or the like, additional local injection can be performed after an endoscope treatment tool for local injection (for example, a local injection needle) is pulled out. In such a case, additional local injection is performed on the submucosa using a high frequency knife having a water supply function. 
     SUMMARY 
     A treatment tool includes a sheath, a hollow pipe extending in the sheath and an elastically deformable constricting member. The hollow pipe includes a flow channel formed in a direction of a longitudinal axis of the hollow pipe and extending between a distal end of the hollow pipe and a proximal end of the hollow pipe. The elastically deformable constricting member includes a first end that is reversibly insertable into the flow channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an overall view of an endoscope treatment system according to a first embodiment. 
         FIG.  2    is an overall view of a treatment tool of the endoscope treatment system according to the first embodiment. 
         FIG.  3    is a perspective view of a distal end portion of the treatment tool according to the first embodiment. 
         FIG.  4    is a cross-sectional view of the distal end portion of the treatment tool according to the first embodiment. 
         FIG.  5    is a cross-sectional view of the distal end portion of the treatment tool according to the first embodiment. 
         FIG.  6    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  7    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  8    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  9    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  10    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  11    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  12    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  13    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the first embodiment. 
         FIG.  14    is a cross-sectional view of a distal end portion of a treatment tool of a second embodiment. 
         FIG.  15    is a cross-sectional view of the distal end portion of the treatment tool of the second embodiment. 
         FIG.  16    is a perspective view of a constricting member of the second embodiment. 
         FIG.  17    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the second embodiment. 
         FIG.  18    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the second embodiment. 
         FIG.  19    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the second embodiment. 
         FIG.  20    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the second embodiment. 
         FIG.  21    is a cross-sectional view of a distal end portion of a treatment tool of a third embodiment. 
         FIG.  22    is a cross-sectional view of the distal end portion of the treatment tool of the third embodiment. 
         FIG.  23    is a perspective view of a constricting member of the third embodiment. 
         FIG.  24    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the third embodiment. 
         FIG.  25    is a cross-sectional view of a distal end portion of a treatment tool of a modified example of the third embodiment. 
         FIG.  26    is a perspective view of a constricting member of a modified example of the third embodiment. 
         FIG.  27    is a cross-sectional perspective view of a distal end portion of a treatment tool of a fourth embodiment. 
         FIG.  28    is a cross-sectional view of the distal end portion of the treatment tool of the fourth embodiment. 
         FIG.  29    is a cross-sectional view of the distal end portion of the treatment tool of the fourth embodiment. 
         FIG.  30    is a side view of an operation part of the treatment tool of the fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     First Embodiment 
     An endoscope treatment system  300  according to a first embodiment of the present disclosure will be described with reference to  FIG.  1    to  FIG.  5   . 
       FIG.  1    is an overall view of the endoscope treatment system  300  according to the embodiment. 
     [Endoscope Treatment System  300 ] 
     As shown in  FIG.  1   , the endoscope treatment system  300  includes an endoscope  200  and a treatment tool  100 . 
     The treatment tool  100  is used to be inserted into the endoscope  200  and used. 
     [Endoscope  200 ] 
     The endoscope  200  is a known flexible endoscope. The endoscope  200  includes an insertion part  202  inserted into the body from a distal end thereof, and an operation part  207  attached to a proximal end of the insertion part  202 . 
     The insertion part  202  has an imaging part  203 , a bending part  204 , and a flexible part  205 . The imaging part  203 , the bending part  204 , and the flexible part  205  are disposed in the insertion part  202  in sequence from the distal end. 
     A channel  206  into which the treatment tool  100  is inserted is provided in the insertion part  202 . A distal opening section  206   a  of the channel  206  is formed in the distal end of the insertion part  202 . 
     The imaging part  203  includes an imaging device such as a CCD, a CMOS, or the like. The imaging part  203  is configured to image an area that is a treatment object. The imaging part  203  can image a hollow pipe  2  of the treatment tool  100  in a state in which the treatment tool  100  protrudes from the distal opening section  206   a  of the channel  206 . 
     The bending part  204  is curved according to an operation of the operation part  207  by an operator. The flexible part  205  is a tubular area having flexibility. 
     The operation part  207  is connected to the flexible part  205 . The operation part  207  has a grip  208 , an input part  209 , a proximal opening section  206   b  of the channel  206 , and a universal cord  210 . The grip  208  is an area gripped by the operator. The input part  209  receives an operation input to curve the bending part  204 . The universal cord  210  outputs the image imaged by the imaging part  203  to the outside. The universal cord  210  is connected to a display device such as a liquid crystal display or the like via an image processing device including a processor or the like. 
     [Treatment Tool  100 ] 
       FIG.  2    is an overall view of the treatment tool  100 . 
     The treatment tool (treatment tool for an endoscope)  100  includes a sheath  1 , the hollow pipe  2 , an operation wire  4 , and an operation part  5 . In the following description, in a longitudinal direction A of the treatment tool  100 , a side inserted into the body of the patient is referred to as “a distal side A 1 ” and a side of the operation part  5  is referred to as “a proximal side A 2 .” In  FIG.  2   , a distal part of the treatment tool  100  is shown as being enlarged. 
     The sheath  1  has flexibility and insulation. The sheath  1  is an elongated resin member and extending from a distal end  1   a  to a proximal end  1   b.  The sheath  1  has an outer diameter that enables insertion into the channel  206  of the endoscope  200  shown in  FIG.  1   . The sheath  1  is provided to be advancable and retractable in the channel  206 . As shown in  FIG.  1   , in a state in which the sheath  1  is inserted into the channel  206 , the distal end  1   a  of the sheath  1  is configured to protrude from and retract to the distal opening section  206   a  of the channel  206 . 
       FIG.  3    is a perspective view of a distal end portion of the treatment tool  100 .  FIG.  4    and  FIG.  5    are cross-sectional views of the distal end portion of the treatment tool  100 . As shown in  FIG.  4   , a pipe holder (a pipe holding member)  11  having a through-hole  12  passing in the longitudinal direction A is attached to the distal end  1   a  of the sheath  1 . The pipe holder  11  is formed of an insulating material. A stepped portion  13  is formed in a circumferential edge portion of the through-hole  12  in a distal end surface  15  of the pipe holder  11 . The stepped portion  13  is a concave portion with a size into which a flange  21  of the hollow pipe  2 , which will be described below, is capable of being inserted. The hollow pipe  2  is inserted into the through-hole  12 . 
     The hollow pipe  2  is a substantially round rod-shaped member formed of a metal. The hollow pipe  2  is formed of a metal material having electric conductivity such as stainless steel or the like. The hollow pipe  2  has electric conductivity. The hollow pipe  2  is a tubular member in which a flow channel  23  is formed in the longitudinal direction A. The flow channel  23  extends between a distal end  2   a  and a proximal end  2   b  of the hollow pipe  2 . The hollow pipe  2  has a tube main body  20  and the flange  21 . The flange  21  is provided on the distal end of the tube main body  20 . The flange  21  has an annular shape with an outer diameter greater than that of the tube main body  20 . In a front view when the flange  21  is seen in a direction along the longitudinal direction A, an outer circumference of the flange  21  is formed in a circular shape concentric with the outer circumference of the tube main body  20 . A distal opening  22   a  that is a distal end of the flange  21  is opened. A side hole (an opening)  27  in communication with the flow channel  23  is formed in the tube main body  20  of the hollow pipe  2 . The side hole  27  is partially open in a circumferential direction of the hollow pipe  2 . 
     In the embodiment, while the flange  21  has been described as being an annular shape with an outer diameter greater than that of the tube main body  20 , the flange  21  may be not only an annular shape but also a polygonal shape such as a triangular shape, a rectangular shape, or the like, or an elliptical shape. 
     The operation wire  4  is attached to a proximal end of the tube main body  20 . The operation wire  4  is formed of a metal material having electric conductivity such as stainless steel or the like. A water supply pipeline  42  is formed in the operation wire  4  throughout the entire length. The operation wire  4  is, for example, a dense winding coil. The operation wire  4  is inserted through an internal space of the sheath  1 . 
     The proximal end  2   b  of the hollow pipe  2  is connected to a distal end  4   a  of the operation wire  4 . The proximal end  2   b  of the hollow pipe  2  and the distal end  4   a  of the operation wire  4  are connected by a connecting pipe  7 . The proximal end  2   b  of the hollow pipe  2  and the distal end  4   a  of the operation wire  4  are disposed in the through-hole of the connecting pipe  7  in a state in which they are in contact with each other. The proximal end  2   b  of the hollow pipe  2  and the distal end  4   a  of the operation wire  4  are fixed to the connecting pipe  7 . An opening  23   a  of the proximal end  2   b  of the tube main body  20  is connected to the operation wire  4 . The water supply pipeline  42  is in communication with the proximal end of the flow channel  23  of the hollow pipe  2 . 
     A constricting member  8  is attached to the connecting pipe  7 . As shown in  FIG.  3    to  FIG.  5   , the constricting member  8  is attached to a distal side of the connecting pipe  7 . The constricting member  8  corresponds to an elastically deformable constricting member. The constricting member  8  has a semi-cylindrical shape in which a cylinder member is divided in the longitudinal direction A. The constricting member  8  has a contacting surface  82 . The contacting surface  82  of the constricting member  8  is disposed to face an outer surface of the hollow pipe  2  and come into contact with the outer surface. The constricting member  8  includes a constricting part  81 . The constricting part  81  corresponds to a first end of the constricting member  8 . The constricting part  81  is a protrusion having a size such that the protrusion can enter the side hole  27  of the hollow pipe  2 . The constricting part  81  extends to a distal side from the contacting surface  82  disposed along the outer surface of the hollow pipe  2 . As shown in  FIG.  5   , the constricting part  81  has a constricting surface  811  extending in a direction crossing a center axis O of the hollow pipe  2  in the longitudinal direction A. In the embodiment, the constricting surface  811  is substantially perpendicular to the center axis O and directed toward the proximal side. 
     The constricting part  81  is disposed outside the flow channel  23  of the hollow pipe  2 . Specifically, in a natural state in which an external force is not applied, the constricting part  81  is disposed at a position where it is flush with an inner circumferential surface of the flow channel  23  of the hollow pipe  2  or at a position of an outer side of the inner wall surface. At least the constricting part  81  in the constricting member  8  is configured to be elastically deformable. In the embodiment, the constricting member  8  is formed of an elastically deformable material as a whole. 
     The operation wire  4  is covered with a cover tube  6  having insulation throughout the entire length. A distal end portion of the cover tube  6  extends to the connecting pipe  7  and covers a proximal portion of the connecting pipe  7 . A proximal end  83  of the constricting member  8  is covered with the distal end portion of the cover tube  6 . The cover tube  6  is, for example, a heat shrinkable tube. A liquid does not leak from the water supply pipeline  42  of the operation wire  4  by covering the outer circumference of the operation wire  4  with the cover tube  6 . 
     The tube main body  20  supplies the high frequency current supplied from the operation wire  4  connected to the operation part  5  to the flange  21 . When the high frequency current is supplied from the operation wire  4  to the hollow pipe  2 , the tube main body  20  and the flange  21  function as a monopolar electrode configured to output the high frequency current to the biological tissue. 
     The hollow pipe  2  is provided to be inserted into the through-hole  12  of the pipe holder  11  and able to advance and retract with respect to the sheath  1 . The hollow pipe  2  is capable of protruding from the through-hole  12  of the pipe holder  11  toward the distal side Al.  FIG.  4    is a cross-sectional view when the hollow pipe  2  is disposed at a position retracted most, and  FIG.  5    is a cross-sectional view when the hollow pipe  2  is disposed at a position advanced most. The center axis O of the hollow pipe  2  in the longitudinal direction A substantially coincides with a center axis of the sheath  1  in the longitudinal direction A. 
     As shown in  FIG.  1    and  FIG.  2   , the operation part  5  has an operation part main body  51 , a slider  52 , a power feed connector  53 , and a liquid supply port  54 . A distal end of the operation part main body  51  is connected to the proximal end  1   b  of the sheath  1 . The operation part main body  51  has an internal space into which the operation wire  4  is capable of being inserted. The operation wire  4  passes through the internal space of the sheath  1  and the internal space of the operation part main body  51  and extends to the slider  52 . 
     The slider  52  is attached to be movable with respect to the operation part main body  51  in the longitudinal direction A. The slider  52  is attached to the sheath  1  connected to the operation part main body  51  via an O-ring. A proximal end of the operation wire  4  is attached to the slider  52 . When the operator operates the slider  52  to relatively advance and retract with respect to the operation part main body  51 , the operation wire  4  and the hollow pipe  2  advance or retract. 
     The power feed connector  53  is fixed to the slider  52 . The power feed connector  53  is connected to the proximal end of the operation wire  4  via a conductive wire (not shown). The power feed connector  53  is configured to be connected to a high frequency power supply device (not shown), and the high frequency current supplied from the high frequency power supply device is supplied to the hollow pipe  2  via the power feed connector  53  and the operation wire  4 . 
     The liquid supply port  54  is provided in the slider  52 . The liquid supply port  54  is in communication with the proximal end of the water supply pipeline  42  of the operation wire  4  via the water supply pipeline formed in the slider  52 . The liquid supplied from the liquid supply port  54  passes through the water supply pipeline of the slider  52 , the water supply pipeline  42  of the operation wire  4  and the flow channel  23  to be discharged from the distal opening  22   a  (shown in  FIG.  5   ). 
     The operation wire  4  and the hollow pipe  2  advance and retract into the sheath  1  when the operator operates the slider  52  to relatively advance and retract with respect to the operation part main body  51 . The hollow pipe  2  is capable of being accommodated in the stepped portion  13  of the pipe holder  11  upon retract. A length of the longitudinal direction A from the distal end portion of the hollow pipe  2  to the constricting member  8  is greater than the length of the pipe holder  11 . 
     As shown in  FIG.  7   , when the slider  52  is further pressed at a position where the constricting member  8  comes into contact with the proximal end of the pipe holder  11 , a force pressed toward the proximal side is applied to the constricting part  81 . Here, the constricting member  8  is also pressed by the operation wire  4  on the distal side. As a result, the constricting part  81  is compressed and deformed in the longitudinal direction A, and the constricting part  81  deforms to extend in a direction crossing the longitudinal direction A. As a result, the constricting part  81  protrudes from the side hole  27  into the flow channel  23  to narrow the flow channel  23 . That is, the constricting part  81  protrudes into the flow channel  23 , and the constricting surface  811  narrows a part of the flow channel  23 . As a result, the flow channel  23  is partially occluded by protrusion of the constricting part  81 , and an opening area is narrowed. The flow channel  23  is narrowed once by the constricting part  81 . The water pressure (water supply pressure) is increased as the liquid supplied to the flow channel  23  of the hollow pipe  2  passes through a place narrowed by the constricting part  81 . The liquid with the increased water pressure is supplied from the distal opening  22   a.  As a result, a water force of the liquid can be increased in the flow channel  23 , and the liquid can be supplied in a state in which the water force is strengthened from the distal opening  22   a.  For example, even when the water pressure of the liquid passing through the water supply pipeline of the slider  52  and the water supply pipeline  42  of the operation wire  4  is lowered, the water force can be increased in the flow channel  23  of the hollow pipe  2 , and the liquid can be supplied in a state in which the water force is strengthened from the distal opening  22   a.    
     While the example in which the constricting surface  811  is substantially perpendicular to the center axis O and directed toward the proximal side has been shown in the embodiment, the orientation of the constricting surface  811  is not limited to the example. The constricting surface  811  may be configured to narrow a part of a flow of the fluid in the flow channel  23 , and the constricting surface  811  may be inclined in a direction crossing the longitudinal direction A. 
     When the slider  52  is retracted and the operation wire  4  and the hollow pipe  2  are retracted with respect to the sheath  1 , the constricting member  8  is separated from the pipe holder  11 . Accordingly, the constricting member  8  returns to a natural state in which an external force is not applied to the constricting member  8 , and compression of the constricting part  81  is released. When the compression of the constricting part  81  is released, the constricting part  81  returns to a state substantially flush with the inner wall of the flow channel  23  as shown in  FIG.  4    from a state protruding into the flow channel  23  as shown in  FIG.  5   . That is, when a relative position of the hollow pipe  2  with respect to the sheath  1  is displaced, the constricting part  81  protrudes from and retracts into the side hole  27  with respect to the flow channel  23 . A type in which the constricting part  81  is positioned on an inner side of the inner circumferential surface of the flow channel  23  in the radial direction and the flow channel  232  is narrowed as the tip of the constricting part  81  protrudes from the side hole  27  into the flow channel  23  is referred to as a high water pressure configuration. The high water pressure configuration corresponds to a first position of the hollow pipe  2  relative to the sheath  1 . A type in which the constricting part  81  is flush with the inner circumferential surface of the flow channel  23  and located on an outer side of the inner circumferential surface in the radial direction is referred to as a low water pressure configuration. The low water pressure configuration corresponds to a second position of the hollow pipe  2  relative to the sheath  1 . The constricting member  8  configures the low water pressure configuration in a natural state in which an external force is not applied, and the constricting part  81  is deformed from the low water pressure configuration by the application of the external force to configure the high water pressure configuration. In the first position, a cross-section of the flow channel  23  has a first area at a position. The first end of the elastically deformable constricting member is inserted at the position. In the second position, the cross-section of the flow channel has a second area at the position. The first end of the elastically deformable constricting member is inserted. The first area is less than the second area. 
     [Method for Using Treatment Tool for Endoscope] 
     Next, an example of method for using the treatment tool  100  for an endoscope according to the embodiment will be described. Specifically, local injection treatment, incision-peeling treatment and hemostasis treatment of a lesioned part in endoscopic treatment such as endoscopic submucosal dissection (ESD) or the like will be described. The operator specifies a lesioned part using a known method. For example, the operator inserts the insertion part  202  of the endoscope  200  into the digestive canal (for example, the gullet, the stomach, the duodenum, the large intestine), and specifies the lesioned part while observing the image obtained by the imaging part  203  of the endoscope. 
     Next, the operator inserts the treatment tool  100  into the channel  206 , and causes the distal end  1   a  of the sheath  1  to protrude from the distal opening section  206   a  of the insertion part  202 . The operator causes the slider  52  of the operation part  5  to relatively advance with respect to the operation part main body  51  and causes the hollow pipe  2  to protrude from the distal end  1   a  of the sheath  1  toward the distal side. 
     The operator performs an operation of moving the slider  52  toward the distal side A 1  with respect to the operation part main body  51 , and moves the hollow pipe  2  toward the distal side A 1 . As a result, the flange  21  of the hollow pipe  2  protrudes toward the distal side A 1  with respect to the sheath  1 . Here, when the slider  52  is pushed toward the distal side, and as shown in  FIG.  4   , when the operation wire  4  and the hollow pipe  2  advance with respect to the sheath  1 , the operation wire  4  and the hollow pipe  2  advance to a position where a distal end  84  of the constricting member  8  abuts a proximal end surface  14  (a proximal end wall) of the pipe holder  11 . The operation wire  4  and the hollow pipe  2  can advance and retract from a position where the flange  21  is accommodated in the stepped portion  13  to a position where the constricting member  8  comes into contact with the proximal end surface  14  of the pipe holder  11 . 
     The operator pushes the distal end of the hollow pipe  2  against the lesioned part into which a liquid for local injection (local injection liquid) is injected, and supplies water in a state in which the distal opening  22   a  is pushed against the tissue (a local injection step). When the hollow pipe  2  is pushed against the lesioned part, the hollow pipe  2  protrudes most, the constricting member  8  comes into contact with the proximal end surface  14  of the pipe holder  11 , and thus, the constricting part  81  is pressed. As a result, the constricting part  81  protrudes into the flow channel  23 . In this state, the liquid such as a physiological saline solution or the like is supplied from the liquid supply port  54  to the water supply pipeline  42  of the slider  52 . The liquid passes through the water supply pipeline  42  of the operation wire  4  and the flow channel  23  and is supplied (discharged) from the distal opening  22   a  toward the distal side. The flow channel  23  has an opening area reduced at a position of the constricting part  81 . Accordingly, the liquid supplied to the flow channel  23  passes through the place where the flow channel is narrowed by the constricting part  81  that was protruded, and thus, the water force is strengthened. Accordingly, the liquid can be supplied from the distal opening  22   a  in a state in which the water force is strong. As a result, the liquid with the strong water force can be supplied to inflate the lesioned part in a state in which the distal opening  22   a  is pushed against the mucous membrane of the lesioned part. In the local injection treatment for inflating the lesioned part before incision, the local injection may be performed by punching the lesioned part with the hollow needle using a known local injection device. 
     After the lesioned part is inflated, the operator performs incision and peeling treatment (incision peeling step). Electrical conduction by the high frequency current to the hollow pipe  2  is performed from the high frequency power supply device (not shown) connected to the power feed connector  53  of the operation part  5  through the power feed connector  53  and the operation wire  4 . The flange  21  of the conducted hollow pipe  2  functions as a high frequency knife. For example, the operator moves the flange  21  in a lateral direction perpendicular to a longitudinal axis C, and the mucous membrane (tissue) in contact with the flange  21  is incised. After the lesioned mucous membrane portion is completely incised in the circumferential direction, the flange  21  abuts a slit where a periphery of the lesioned mucous membrane portion is incised, and the lesioned mucous membrane portion is entirely incised and peeled. In addition, the operator peels the submucosa of the incised lesioned part while lifting the mucous membrane of the incised lesioned part and exposing the submucosa in a state in which the treatment tool  100  advances and the high frequency current is applied. 
     The operator can perform additional local injection treatment. The operator causes the hollow pipe  2  to protrude toward the distal side A 1  most. The operator pushes the flange  21  against an area where the local injection liquid is additionally injected, and the liquid is supplied from the distal opening  22   a  (additional local injection step). As described above, when the hollow pipe  2  protrudes most and the constricting member  8  comes into contact with the proximal end surface  14  of the pipe holder  11  to press the constricting part  81 , the constricting part  81  protrudes into the flow channel  23 . The flow channel  23  has an opening area reduced at a position of the constricting part  81 . The liquid supplied to the water supply pipeline of the slider  52 , the water supply pipeline  42  of the operation wire  4  and the flow channel  23  from the liquid supply port  54  in this state passes through a place where the flow channel is narrowed by the protruded constricting part  81 , and thus, the water force is strengthened. Accordingly, the liquid supplied to the flow channel  23  can be supplied from the distal opening  22   a  in a state in which the water force is strengthened. The distal opening  22   a  abuts the mucous membrane of the lesioned part to push the flange  21 , and additional local injection can be performed on the lesioned part when the liquid is supplied in a state in which the water force is strengthened. 
     When bleeding occurs during the incision and peeling treatment, the operator performs hemostasis treatment. The operator cauterizes the bleeding point to perform hemostasis while pressing the flange  21  that has become hot due to conduction by the high frequency current (hemostasis step). 
     The operator can clean the operation site in cleaning step. Here, the hollow pipe  2  is at the position where the hollow pipe  2  is retracted in comparison with the time of the local injection step and the incision peeling step. Specifically, in a state in which the constricting member  8  is disposed at a position separated from the proximal end surface  14  of the pipe holder  11  toward the proximal side A 2 , a liquid such as a physiological saline solution or the like is supplied. The constricting member  8  is in the natural state in which the external force is not applied at a position where the constricting member  8  is separated from the proximal end surface  14  of the pipe holder  11 . When the constricting member  8  is in the natural state, for example, the constricting part  81  is to be flush with the inner surface of the flow channel  23  of the tube main body  20 . Alternatively, the constricting part  81  is located in the side hole  27  on the outer side of the inner surface of the flow channel  23  in the radial direction. That is, the constricting part  81  is disposed at a position that does not interfere with the flow channel  23 . In this state, the liquid can be supplied in the hollow pipe  2  in a state in which the water force is lower than upon the local injection. During the operation site cleaning, the liquid is supplied at a position where the flange  21  is separated from the tissue. When the liquid is supplied in a state in which the water force is high upon local injection at a position where the flange  21  is separated from the tissue, bubbles are generated, the liquid splashes from the cleaning target area, and a field of vision of the imaging part  203  of the endoscope is reduced, which interferes with the treatment. However, when the constricting part  81  is disposed at a position that does not interfere with the flow channel  23 , the water force becomes weaker than that upon local injection, and the cleaning is performed favorably. Upon the operation site cleaning, the constricting part  81  may be positioned on the proximal side of the hollow pipe  2  separated from the proximal end surface  14 . 
     The operator can continue the above-mentioned operation (treatment), incise the lesioned part finally, and terminate the ESD procedure. 
     According to the treatment tool  100  of the embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed. According to the treatment tool  100  of the embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed without inserting and removing the treatment tool  100  into/from the channel  206  of the endoscope  200 . 
     Hereinabove, while the first embodiment of the present disclosure has been described in detail with reference to the accompanying drawings, a specific configuration is not limited to the embodiment and also includes design changes or the like without departing from the spirit of the present disclosure. In addition, the components shown in the above-mentioned embodiment and modified examples may be combined appropriately. In the following description, the common components as those as already described are designated by the same reference signs and overlapping description will be omitted. 
     The constricting member  8  is not limited to a substantially semi-cylindrical shape. For example, the constricting member  8  may have an elongated shape extending in the longitudinal direction A to cover a region on the proximal side of the side hole  27  and the side hole  27 . 
     MODIFIED EXAMPLE 1-1 
     A modified example of the embodiment will be described with reference to  FIG.  6    and  FIG.  7   . As shown in  FIG.  6    and  FIG.  7   , a concave portion  141  may be formed in the proximal end surface  14  of the pipe holder  11 . The concave portion  141  is recessed from the proximal end surface  14  toward the distal side in a boundary portion between the proximal end surface  14  and the through-hole  12 . The concave portion  141  is an opening having a size into which the distal end portion of the constricting member  8  can enter. Specifically, the concave portion  141  is an opening having a size that comes into contact with the constricting member  8  when the distal end portion of the constricting member  8  intrudes thereinto. In the concave portion  141 , a surface  14   a  positioned on the distal side perpendicular to the longitudinal axis of the through-hole  12  constitutes the proximal end surface  14   a.  A portion  143  on an outer side of the concave portion  141  in the radial direction constitutes a restriction part  143  protruding toward the proximal side A 2  of the longitudinal axis of the through-hole. The restriction part  143  corresponds to a protrusion. As shown in  FIG.  7   , the operation wire  4  and the hollow pipe  2  advance, and the distal end  84  of the constricting member  8  enters the concave portion  141  and comes in contact therewith. When the operation wire  4  is pressed at the distal side A 1  in a state in which the distal end portion of the constricting member  8  enters the concave portion  141 , the distal end  84  comes into contact with the proximal end surface  14   a  to apply an external force to the constricting part  81  and compress the constricting part  81 . Since an outer circumferential portion of the constricting member  8  is disposed in the concave portion  141  and covered with the restriction part  143 , the compression force of the constricting part  81  is applied toward the center axis O. As a result, the compressed constricting part  81  protrudes from an outer side of the tube main body  20  into the flow channel  23 . Accordingly, the compressed constricting part  81  can smoothly protrude into the flow channel  23 . In addition, since the compressed constricting part  81  protrudes into the flow channel  23  in the radial direction, the constricting surface  811  tends to be oriented in a direction substantially perpendicular to the center axis O. As a result, the opening area of the flow channel  23  can be more reliably narrowed, and switching of the water force of the flow channel  23  by the constricting part  81  is reliably performed. Accordingly, the treatment tool  100  is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.    
     MODIFIED EXAMPLE 1-2 
     A modified example of the embodiment will be described with reference to  FIG.  8    and  FIG.  9   . The concave portion  141  may have a shape in which the constricting member  8  is inserted and the constricting part  81  can enter the flow channel  23 , and is not limited to the shape shown in  FIG.  6   . As shown in  FIG.  8    and  FIG.  9   , a concave portion  142  may have a tapered shape. The concave portion  142  has a tapered surface (inclined surface) formed such that the opening area is reduced from the proximal end surface  14  of the pipe holder  11  toward the distal side. The opening of the proximal end portion of the concave portion  142  has a size such that the distal end portion of the constricting member  8  can be entered. 
     As shown in  FIG.  9   , the operation wire  4  and the hollow pipe  2  advance, and the distal end  84  of the constricting member  8  enters the concave portion  142  and comes into contact therewith. When the operation wire  4  is pressed on the distal side A 1  in a state in which the distal end portion of the constricting member  8  enters the concave portion  142 , an external force is applied to the constricting part  81  to compress the constricting part  81 . When the hollow pipe  2  advances, an outer circumferential edge  841  of the distal end  84  of the constricting part  81  is pressed along the tapered surface while coming into contact with the concave portion  142 , and the constricting part  81  is elastically deformed to protrude into the flow channel  23 . As a result, the constricting part  81  can smoothly protrude into the flow channel  23  in accordance with the operation of advancing the operation wire  4  and the hollow pipe  2 . In the modified example, the inner circumferential surface of the constricting part  81  functions as the constricting surface  811 . As a result, the constricting part  81  can smoothly protrude into the flow channel  23 , and the opening area of the flow channel  23  can be more reliably narrowed. Meanwhile, the constricting part  81  gradually returns to its original position where it does not protrude into the flow channel  23  in accordance with the operation of retracting the operation wire  4  and the hollow pipe  2 . As a result, switching of the water force of the flow channel  23  is reliably performed. Accordingly, the treatment tool  100  is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.    
     In the distal end portion of the connecting pipe  7 , a portion facing the constricting member  8  with the center axis sandwiched therebetween has a tapered surface  74 . The tapered surface  74  of the connecting pipe  7  is inclined to reduce a diameter toward the distal end portion. The tapered surface  74  is inclined not to come into contact with the concave portion  142  before the distal end of the constricting member  8  comes into contact with the concave portion  142 . Accordingly, the contact of the constricting part  81  with the concave portion  142  is not prevented by the connecting pipe  7 . The tapered surface  74  of the connecting pipe  7  is not a required configuration. As described above, the connecting pipe  7  may have a shape without interfering with the contact of the constricting part  81  with the concave portion  142 . 
     In this example shown in  FIG.  8    and  FIG.  9   , while the example of the concave portion  142  having a substantially conical opening formed coaxially with the through-hole  12  and a tapered surface has been shown, the concave portion  142  is not limited to the shape. For example, the concave portion  142  may be formed at only a position facing the constricting member  8 , and a tapered surface may be formed on the concave portion  142 . The concave portion  141  may be formed in the proximal end surface  14  of the pipe holder  11 . 
     MODIFIED EXAMPLE 1-3 
     A modified example of the embodiment will be described with reference to  FIG.  10    and  FIG.  11   . The constricting member  8  of the modified example shown in  FIG.  8    and  FIG.  9    may further include a slit  86 . The slit  86  is located on the distal side of the contacting surface  82  to the hollow pipe  2  in the longitudinal direction A. The slit  86  is formed in a direction substantially perpendicular to the longitudinal direction A from an outer surface  85  of the constricting member  8 . A position of the slit  86  in the longitudinal direction A overlaps a proximal edge  271  of the side hole  27  of the hollow pipe  2  or is provided on the distal side A 1  other than the proximal edge  271 . As shown in  FIG.  11   , the operation wire  4  and the hollow pipe  2  advance, and the outer circumferential edge  841  of the distal end  84  of the constricting member  8  enters the concave portion  142  and comes into contact therewith. When the operation wire  4  is pressed on the distal side A 1  in a state in which the distal end portion of the constricting member  8  enters the concave portion  142 , an external force is added to the constricting part  81 , and the constricting part  81  electrically deforms using the slit  86  as an origin. The constricting part  81  is guided to the inclination of the concave portion  142  and protrudes from the outside of the tube main body  20  into the flow channel  23 . As a result, the compressed constricting part  81  can smoothly protrude in the flow channel  23 . As a result, the opening area of the flow channel  23  can be more reliably narrowed, and switching of the water force of the flow channel  23  by the constricting part  81  is reliably performed. Accordingly, the treatment tool  100  is changed between the low water pressure configuration and the high water pressure configuration in accordance with relative movement of the hollow pipe  2  with respect to the sheath  1 , and is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.    
     MODIFIED EXAMPLE 1-4 
     In the embodiment and modified example, while the example in which the side hole  27  is opened at one place in the circumferential direction of the hollow pipe  2  and the constricting part  81  protrudes and retracts into the flow channel  23  has been shown, each of the number of the constricting part  81  and the side hole  27  is not limited to one and may be provided in plural. As shown in  FIG.  12    and  FIG.  13   , the treatment tool  100  may include the pair of side holes  27  and the pair of constricting parts  81  at facing positions with the center axis O of the hollow pipe  2  sandwiched therebetween. As shown in  FIG.  13   , the operation wire  4  and the hollow pipe  2  advance, and the outer circumferential edge  841  of the distal end  84  of the constricting member  8  enters the concave portion  142  and comes into contact therewith. When the operation wire  4  is pushed on the distal side A 1  in a state in which the distal end portion of the constricting member  8  enters the concave portion  142 , an external force is added to the constricting part  81 , the pair of constricting parts  81  are guided to the inclination of the concave portion  142 , and the distal end portion protrudes from an outer side of the tube main body  20  into the flow channel  23 . In the case of the example, a surface of the constricting part  81  in the longitudinal direction A functions as the constricting surface  811 . According to the treatment tool  100  of the example, the pair of constricting parts  81  can smoothly protrude in the flow channel  23 . As a result, the opening area of the flow channel  23  can be more reliably narrowed, and switching of the water force of the flow channel  23  by the constricting part  81  is reliably performed. Accordingly, the treatment tool  100  is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.  A difference between a place where the opening area of the flow channel  23  is wide and a place where the opening area is narrow can be increased and the liquid can be supplied in a state in which the water force is higher in accordance with the configuration in which the pair of constricting parts  81  advance and retract into the flow channel  23 . Meanwhile, when the operation wire  4  and the hollow pipe  2  retract, the pair of constricting parts  81  are moved outward in the radial direction and changed in a state in which the constricting part  81  does not interfere with the flow channel  23 . Accordingly, the water force of the liquid supplied from the distal opening  22   a  can be greatly changed. While not shown, each of the constricting parts in the example may include the slit  86  shown in  FIG.  10    and  FIG.  11   . 
     According to the treatment tool  100  of the embodiment and modified example, the constricting part  81  can protrude and retract with respect to the flow channel  23  and the opening area of the flow channel  23  can be changed in accordance with the operation of causing the operation wire  4  and the hollow pipe  2  to advance and retract with respect to the sheath  1 . That is, by operating the slider  52  of the operation part  5  to advance and retract, the opening area of the flow channel  23  can be changed, and the water force of the liquid supplied from the distal opening  22   a  via the flow channel  23  can be changed. Accordingly, for example, the liquid can be supplied from the distal opening  22   a  in a state in which the water force is high at the time of the local injection and re-local injection, and the liquid can be supplied from the distal opening  22   a  in a state in which the water force is low at the time of the operation site cleaning. 
     Second Embodiment 
     A treatment tool  100 B according to a second embodiment will be described with reference to  FIG.  14    to  FIG.  16   . In the following description, the same components as described above are designated by the same reference signs and overlapping descriptions thereof will be omitted. 
       FIG.  14    and  FIG.  15    are cross-sectional views showing a distal end portion of the treatment tool  100 B. 
     Like the treatment tool  100  of the first embodiment, the treatment tool (treatment tool for an endoscope)  100 B configures an endoscope treatment system together with the endoscope  200 . The treatment tool  100 B includes a sheath  1 , a hollow pipe  2 , a pipe holder  11 B, a constricting member  8 B, an operation wire  4 , a connecting pipe  7 B, and an operation part  5 . 
     In the embodiment, the constricting member  8  is provided on the pipe holder  11 B. An accommodating section  16  (concave portion) in which the constricting member  8 B is accommodated is formed in an intermediate section of the pipe holder  11 B in the longitudinal direction A. The accommodating section  16  is an opening that is opened in the through-hole  12  and recessed from the through-hole  12  toward the outer circumference of the pipe holder  11 B in the radial direction. In the embodiment, the accommodating section  16  is a circular opening. 
     The hollow pipe  2  has the side holes  27  formed at two places separated in the circumferential direction of the tube main body  20 . In this example shown in  FIG.  14    and  FIG.  15   , the two side holes  27  are open at positions separated  180  degrees in the circumferential direction. As shown in  FIG.  14   , the side hole  27 B has a distal edge  272  that is inclined. Specifically, the distal edge  272  of the side hole  27 B is inclined such that an edge portion in the outer surface of the hollow pipe  2  is located on the distal side of the edge portion in the inner surface of the flow channel  23 . 
     Like the first embodiment, the proximal end of the hollow pipe  2  and the distal end of the operation wire  4  are connected by the connecting pipe  7 . The connecting pipe  7  is entirely covered with the cover tube  6 . A distal end  61  of the cover tube  6  comes into contact with an outer surface of the hollow pipe  2  that covers the distal part of the connecting pipe  7 . The side hole  27  is located on a distal side of the cover tube  6 . 
       FIG.  16    is a perspective view of the constricting member  8 B of the embodiment. The constricting member  8 B has a main body  80 , a constricting part  81 B, and a holding part  89 . The main body  80  has a substantially annular shape in which an opening  88  is formed in a central portion. The constricting part  81 B is a protrusion extending from the main body  80  toward a center O 8  of the opening  88  in the radial direction. The constricting part  81 B has a base part  871  and a constricting piece  872  from the opening  88  in the radial direction. The base part  871  is a columnar part extending from the opening  88  in the radial direction. The constricting piece  872  has a square pyramid shape that is tapered from the base part  871  toward the center O 8  of the opening  88 . The constricting piece  872  is configured to be softer than the base part  871  and elastically deformable when an external force is applied. The constricting part  81 B is provided to protrude from each of the positions separated  180  degrees in the circumferential direction of the main body  80 . The pair of holding parts  89  are provided between the pair of constricting parts  81 B, respectively. The holding part  89  has a holding base part  891  and a holding piece  892 . The holding base part  891  is a columnar part extending from the opening  88  in the radial direction. The holding piece  892  has a shape in which a thickness in the longitudinal direction A is reduced from the holding base part  891  toward the center O 8  of the opening  88 . A projection end of the constricting piece  872  has a tip shape, and a projection end of the holding piece  892  has a long side. The holding piece  892  is configured to be softer than the holding base part  891  and elastically deformable when an external force is applied. The constricting member  8 B is a part integrally formed of, for example, an elastic resin, a hard rubber, or the like. 
     As shown in  FIG.  14    and  FIG.  15   , the constricting member  8 B is disposed in the accommodating section  16  of the pipe holder  11 B. An opening dimension of the accommodating section  16  in the radial direction has a size such that the main body  80  of the constricting member  8 B is accommodated in the accommodating section  16  while an outer diameter of the main body  80  of the constricting member  8 B comes in contact therewith. An opening dimension of the accommodating section  16  in the longitudinal direction A is greater than the dimension (thickness) of the main body  80  in the longitudinal direction A. A distal surface or a proximal surface of the constricting member  8 B is adhered to the accommodating section  16 , and an outer circumferential portion of the main body  80  comes into contact with the inner circumferential surface of the accommodating section  16  and is attached thereto. In this example shown, a distal surface of the main body  80  is adhered to a surface of the accommodating section  16  on the distal side. 
     The hollow pipe  2  is inserted through the through-hole  12  of the pipe holder  11 B. The tube main body  20  of the hollow pipe  2  is inserted through the through-hole  12  and the opening  88  of the constricting member  8 B. A distance between the base parts  871  of the pair of constricting parts  81 B and a distance between the holding base parts  891  of the pair of holding parts  89  are greater than the outer diameter of the hollow pipe  2 . The hollow pipe  2  advances and retracts in the opening  88  of the constricting member  8 B while coming into contact with the constricting piece  872  and the holding piece  892 . The holding piece  892  normally comes into contact with the outer circumferential surface of the hollow pipe  2  while being elastically deformed. The pair of constricting pieces  872  are disposed at positions corresponding to the pair of side holes  27 B of the hollow pipe  2 , respectively. The constricting piece  872  electrically deforms when it comes into contact with the outer circumferential surface of the hollow pipe  2 , and bends with respect to the base part  871  in the longitudinal direction A. When the constricting piece  872  moves to the position of the side hole  27 B in accordance with advancement and retraction of the hollow pipe  2 , the constricting piece  872  enters the side hole  27 B and protrudes into the flow channel  23 . In this example, when the hollow pipe  2  is at an accommodating position shown in  FIG.  14   , the constricting piece  872  comes into contact with the outer circumferential surface of the hollow pipe  2  and elastically deformed on the proximal side to be bent. While not shown, the holding piece  892  also elastically deformed to be bent. When the operation wire  4  and the hollow pipe  2  advance and the constricting piece  872  enters the side hole  27 B as shown in  FIG.  15   , the constricting piece  872  returns to its original shape, extends in the radial direction and protrudes into the flow channel  23 . While not shown, the holding piece  892  comes into contact with the outer circumferential surface of the hollow pipe  2  and elastically deformed to be bent. When the operation wire  4  and the hollow pipe  2  retract from a position where the flange  21  of the hollow pipe  2  protrudes to the distal side of the pipe holder  11 B, the constricting piece  872  is guided to the outer side of the hollow pipe  2  along the inclined surface of the distal edge  272  of the side hole  27 B. In addition, by rotating the hollow pipe  2  around the center axis O, the high water pressure state and the low water pressure state may be switched by varying a relative position between the side hole  27  of the hollow pipe  2  and the constricting piece  872 . That is, when the constricting piece  872  is disposed at a position facing the side hole  27 , the constricting piece  872  enters the side hole  27 B and protrudes into the flow channel  23  to become a high water pressure state. When the operation part is rotated to relatively move the hollow pipe  2  with respect to the sheath  1  around the center axis O, the position of the side hole  27  is deviated from the constricting piece  872 , and the constricting piece  872  is removed from the side hole  27 , resulting in a low water pressure state. 
     According to the embodiment, the proximal surface of the constricting piece  872  functions as the constricting surface  811  in accordance with advancement and retraction of the operation wire  4  and the hollow pipe  2 . The constricting piece  872  smoothly protrudes in the flow channel  23  in accordance with advancement and retraction of the operation wire  4  and the hollow pipe  2  with respect to the sheath  1 , and the opening area of the flow channel  23  can be more reliably narrowed. Meanwhile, the constricting piece  872  returns to the original position where it does not protrude in the flow channel  23  in accordance with the operation of retracting the operation wire  4  and the hollow pipe  2 . As a result, switching of the water force of the liquid supplied from the distal opening  22   a  via the flow channel  23  is reliably performed. Accordingly, the treatment tool  100  is configured to change between the low water pressure configuration and high water pressure configuration to easily change the water force of the liquid supplied from the distal opening  22   a  in accordance with relative movement of the hollow pipe  2  with respect to the sheath  1 . 
     In this example, while the example in which the constricting member  8 B has the pair of constricting parts  81 B and the pair of holding parts  89  has been described, the constricting member is not limited thereto. For example, the constricting part  81 B may be provided by one or three or more. The holding part  89  has a function of stably holding the hollow pipe  2  upon advance and retract of the hollow pipe  2 . The holding part  89  is not an essential configuration of the constricting member  8 B for the purpose of changing the water force of the flow channel  23 . 
     According to the treatment tool  100 B of the embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed using the same using method as that of the treatment tool  100  of the first embodiment. According to the treatment tool  100  of the embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed without insertion and removal of the treatment tool  100  into/from the channel  206  of the endoscope  200 . 
     Hereinabove, while the second embodiment of the present disclosure has been described in detail with reference to the accompanying drawings, a specific configuration is not limited to the embodiment and also includes design changes or the like without departing from the spirit of the present disclosure. In addition, the components shown in the above-mentioned embodiment and modified examples may be combined appropriately. 
     While the example in which the distal edge  272  of the side hole  27 B is inclined has been described in the embodiment, the shape of the side hole  27 B is not limited thereto. The side hole  27 B may be open such that the constricting piece  872  of the constricting part  81 B protrudes or retracts. 
     MODIFIED EXAMPLE 2-1 
     A modified example of the embodiment will be described with reference to  FIG.  17    and  FIG.  18   . As shown in  FIG.  17    and  FIG.  18   , the constricting member  8 B may be disposed in a part of the hollow pipe  2  in the circumferential direction. The constricting member  8 B of the example has a semi-circular shape when seen in the longitudinal direction A. For example, the constricting member  8 B may be disposed in a part of the hollow pipe  2  in the circumferential direction, for example, a semi-circular shape, a fan shape, a three-fourths arc, or the like, when seen in the longitudinal direction A. In this example, one constricting part  81 B is provided. An operation of the constricting piece  872  in accordance with advancement and retraction of the hollow pipe  2  is the same as in the second embodiment. The accommodating section  16  of the pipe holder  11 B is formed in a part of the through-hole  12  in the circumferential direction to correspond to the shape of the constricting part  81 B. According to the treatment tool  100 B of the example, like the second embodiment, the constricting piece  872  elastically deforms in accordance with advancement and retraction of the hollow pipe  2 , and is capable of protruding and retracting in the flow channel  23  from the side hole  27 B. Accordingly, the opening area of the flow channel  23  is configured to be more reliably narrowed by the constricting piece  872 , and switching of the water force of the flow channel  23  by the constricting part  81  is reliably performed. Accordingly, the treatment tool  100  is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.  Like the modified example, a contact area between the constricting piece  872  and the outer surface of the hollow pipe  2  is kept small and the hollow pipe  2  is capable of advancing and retracting smoothly due to the configuration of providing the constricting member  8 B in the part of the hollow pipe  2  in the circumferential direction. 
     According to the treatment tool  100 B of the embodiment and modified example, the constricting part  81 B is configured to protrude from or retract into the flow channel  23  and the opening area of the flow channel  23  is capable of being changed in accordance with the operation of causing the operation wire  4  and the hollow pipe  2  to advance and retract with respect to the sheath  1 . That is, the opening area of the flow channel  23  can be changed and the water force of the liquid supplied from the distal opening  22   a  via the flow channel  23  can be changed by advancing and retracting the slider  52  of the operation part  5 . Accordingly, for example, the liquid can be supplied from the distal opening  22   a  in a state in which the water force is high during local injection and re-local injection, and the liquid can be supplied from the distal opening  22   a  in a state in which the water force is low during operation site cleaning. 
     MODIFIED EXAMPLE 2-2 
     A modified example of the embodiment will be described with reference to  FIG.  19    and  FIG.  20   . As shown in  FIG.  19    and  FIG.  20   , the side hole  27 B may be located on the distal side A 1  further than in the embodiment. The side hole  27 B of the example is located on the distal side A 1  by a half between the distal end  2   a  of the hollow pipe  2  and the distal end  61  of the cover tube  6  when the hollow pipe  2  is seen in a direction crossing the center axis O. More specifically, the side hole  27 B is disposed at a position where the constricting member  8 B intrudes into the side hole  27 B in a state in which the flange  21  is accommodated in the stepped portion  13 . 
     According to the above-mentioned configuration, the base part  871  of the constricting part  81  can protrude from the side hole  27 B in the radial direction to narrow the flow channel  23  when the flange  21  is accommodated in the stepped portion  13 , resulting in the state in which the water pressure is high. At this time, the distal edge  272  of the side hole  27 B is inclined from the proximal end of the center axis O toward the distal end. 
     Third Embodiment 
     A treatment tool  100 C according to a third embodiment of the present disclosure will be described with reference to  FIG.  21    to  FIG.  23   . In the following description, the common components as those as already described are designated by the same reference signs and overlapping description will be omitted. 
       FIG.  21    and  FIG.  23    are cross-sectional view showing a distal end portion of the treatment tool  100 C. Like the treatment tool  100  of the first embodiment, the treatment tool (treatment tool for an endoscope)  100 C constitutes an endoscope treatment system together with the endoscope  200 . The treatment tool  100 C includes a sheath  1 C, a hollow pipe  2 , a pipe holder  11 C, a constricting member  8 C, an operation wire  4 , a connecting pipe  7 C, and an operation part  5 . The connecting pipe  7 C, the operation wire  4 , and the hollow pipe  2  have the same configurations as in the second embodiment. 
     In the embodiment, the constricting member  8 C is attached to the pipe holder  11 C. The constricting member  8 C is attached to the distal end  1   a  of the sheath  1  on the distal side Al. Specifically, the constricting member  8 C is provided on a portion of the pipe holder  11 C protruding from the distal end  1   a  of the sheath  1 .  FIG.  23    is a perspective view of the constricting member  8 C. The constricting member  8 C is a resin member having insulation. The constricting member  8 C has a main body  80 C, a constricting part  81 C, and a holding part  89 . The main body  80 C has an arc shape with a size that is flush with the outer circumferential surface of the sheath  1 . The main body  80 C has a contacting surface  82 C to the pipe holder  11 C. As shown in  FIG.  21    and  FIG.  22   , a portion of the pipe holder  11 C protruding from the distal end  1   a  of the sheath  1  on the distal side has a distal stepped portion  17  having a thickness in the radial direction that is smaller than the proximal end portion inserted and fixed into the distal end portion of the sheath  1 . The inner circumferential surface of the main body  80 C constitutes the contacting surface  82 . The contacting surface  82 C is disposed to face the outer circumferential surface of the distal stepped portion  17  of the pipe holder  11 C, and contacts and fixed to the distal stepped portion  17 . An opening  88  is formed in a distal part of the main body  80 C on the side of the center axis O of the sheath  1  and the pipe holder  11 C. 
     The constricting part  81 C is a protrusion extending from the main body  80 C toward the center axis O of the pipe holder  11 C in the radial direction. The constricting part  81 C protrudes toward the through-hole  12  from the contacting surface  82 . The constricting part  81 C has a base part  871  and a constricting piece  872  from the opening  88  in the radial direction. The base part  871  is a columnar part extending from the opening  88  in the radial direction. The constricting piece  872  has a square pyramid shape tapered from the base part  871  toward the center axis O of the pipe holder  11 C. The constricting piece  872  is configured to be softer than the base part  871  and elastically deformable when an external force is applied. The pair of holding parts  89  are provided to protrude from positions separated  180  degrees in the circumferential direction of the main body  80 C. The constricting part  81 C is provided between the pair of holding parts  89 . 
     When the constricting member  8 C is fixed to the distal stepped portion  17  of the pipe holder  11 C, in a natural state in which an external force is not applied to the constricting part  81 C, the constricting part  81 C protrudes toward the center axis O from the inner circumferential surface of the through-hole  12 . The constricting part  81 C protrudes to a position where it comes into contact with the outer surface of the hollow pipe  2  inserted through the through-hole  12 . The constricting piece  872  is disposed at a position corresponding to the side hole  27  of the hollow pipe  2 . The constricting piece  872  elastically deforms when it comes into contact with the outer circumferential surface of the hollow pipe  2 , and bends with respect to the base part  871  in the longitudinal direction A. When positions of the constricting piece  872  and the side hole  27  in the longitudinal direction A coincide with each other in accordance with advancement and retraction of the hollow pipe  2 , the constricting piece  872  enters the side hole  27  and protrudes inside the flow channel  23 . In this example, as shown in  FIG.  21   , when the hollow pipe  2  is located at a retracted position, the constricting piece  872  comes into contact with the outer circumferential surface of the hollow pipe  2  and elastically deformed to be bent on the proximal side. While not shown, the holding piece  892  also elastically deforms and bends. When the operation wire  4  and the hollow pipe  2  advance and the constricting piece  872  enters the side hole  27  as shown in  FIG.  22   , the constricting piece  872  returns to the original shape, extends in the radial direction and protrudes in the flow channel  23 . While not shown, the holding piece  892  comes into contact with the outer circumferential surface of the hollow pipe  2  and elastically deforms to be bent. As shown in  FIG.  21   , the constricting part  81 C is elastically deformed by a load of an external force, and a low water pressure configuration without interfering with the flow channel  23  is configured. As shown in  FIG.  22   , in a natural state in which an external force is not applied, the constricting part  81  returns to the original shape to configure the high water pressure configuration from the low water pressure configuration. Accordingly, the treatment tool  100 C is configured to change between the low water pressure configuration and the high water pressure configuration in accordance with relative movement of the hollow pipe  2  with respect to the sheath  1 , and is configured to be easily change the water force of the liquid supplied from the distal opening  22   a.    
     According to the treatment tool  100 C of the embodiment, like the first embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed. According to the treatment tool  100  of the embodiment, a plurality of treatments such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed without insertion and removal of the treatment tool  100  into/from the channel  206  of the endoscope  200 . 
     According to the treatment tool  100 C of the embodiment, since the constricting member  8 C is disposed at a position protruding from the distal end  1   a  of the sheath  1 , the constricting part  81 C can be disposed at a position where the constricting part  81 C is closest to the projection end of the hollow pipe  2 . As a result, the water force can be increased by the constricting part  81 C at a position closer to the distal opening  22   a  of the hollow pipe  2 . Accordingly, since a distance between the position where the liquid in the flow channel  23  is at a high water pressure and the distal opening  22   a  is short, the water force discharged from the distal opening  22   a  can be increased. 
     Hereinabove, while the third embodiment of the present disclosure has been described in detail with reference to the accompanying drawings, a specific configuration is not limited to the embodiment and also includes design changes or the like without departing from the spirit of the present disclosure. In addition, the components shown in the above-mentioned embodiment and modified examples may be combined appropriately. In the following description, the common components as those as already described are designated by the same reference signs and overlapping description will be omitted. 
     MODIFIED EXAMPLE 3-1 
     A modified example of the embodiment will be described with reference to  FIG.  24    to  FIG.  26   . The constricting member may include a constricting part that is changeable between a position disposed in the flow channel  23  of the hollow pipe  2  and blocking a part of the flow channel and a position without interfering with the flow channel  23 , and it is not limited to the example shown in  FIG.  23   . In addition, the number of the constricting part  81  and the side hole  27  is not limited to one and may be plural. As shown in  FIG.  24    and  FIG.  25   , the constricting member  8 C may be provided at a position that covers the entire circumference of the distal end of the pipe holder  11 C. The constricting member  8 C of the example has a circular shape when seen in the longitudinal direction A. In this example, the pair of side holes  27  are open at facing positions with the center axis O of the hollow pipe  2  sandwiched therebetween, and the constricting part  81 C includes the pair of constricting parts  81  at positions corresponding to the pair of side holes  27 . The pair of holding parts  89  are provided between the pair of constricting parts  81 B in the circumferential direction. The flange  21  of the hollow pipe  2  is disposed on the distal side of the constricting member  8 C. The distal part of the pipe holder  11 C has a diameter smaller than that of the insertion part into the distal end  1   a  of the sheath  1 . The constricting member  8 C is attached to cover the outer circumference of the distal part of the pipe holder  11 C from the distal side of the pipe holder  11 C. The inner circumferential surface of the main body  80 C configures the contacting surface  82 . The constricting member  8 C are mounted and attached to the distal part of the pipe holder  11 C from the outside. An operation of the constricting piece  872  in accordance with advancement and retraction of the hollow pipe  2  is the same as in the third embodiment. 
     According to the configuration in which the pair of constricting parts  81 C protrude and retract into the flow channel  23  from the outside of the pair of side holes  27 , a difference between a place where the opening area of the flow channel  23  is wide and a place where it is narrow can be increased, and the liquid can be supplied in a state in which the water force is higher. Meanwhile, when the operation wire  4  and the hollow pipe  2  retract, the pair of constricting parts  81 C are moved to the outer side of the hollow pipe  2  and changed to a state in which the constricting part  81  does not interfere with the flow channel  23 . Accordingly, the water force of the liquid supplied from the distal opening  22   a  can be largely changed. 
     While not shown, the slit  86  shown in  FIG.  10    and  FIG.  11    may be provided in each of the constricting parts in the example. The holding part  89  has a function of stably holding the hollow pipe  2  upon advance and retract of the hollow pipe  2 . The holding part  89  is not an essential configuration of the constricting member  8 B for the purpose of changing the water force of the flow channel  23 . 
     Fourth Embodiment 
     A treatment tool  100 D according to a fourth embodiment will be described with reference to  FIG.  27    to  FIG.  29   . In the following description, the same components as described already are designated by the same reference signs and overlapping descriptions thereof will be omitted. 
       FIG.  27    is a perspective view showing a distal part of the treatment tool  100 D according to the fourth embodiment, a part of which is shown in a cross section in the longitudinal direction A. The treatment tool  100 D includes a sheath  1 , a hollow pipe  2 , a pipe holder  11 , a connecting member  7 , an operation wire  9  for flow channel adjustment, an operation wire  4  for a knife, and an operation part  5 . The sheath  1 , the pipe holder  11 , and the operation wire  4  for a knife are the same as in the above-mentioned embodiment. The hollow pipe  2  does not include the side hole  27  of the above-mentioned embodiment. The other configurations are the same as in the above-mentioned embodiment. The operation wire  9  for flow channel adjustment is a wire having a hollow portion configured to advance and retract the hollow pipe  2  with respect to the sheath  1 . The operation wire  9  for flow channel adjustment is hollow inside the entire length. The operation wire  9  for flow channel adjustment is inserted into the operation wire  4  for a knife. 
     The connecting member  7  is a member configured to connect the hollow pipe  2  and the operation wire  4  for a knife. The connecting member  7  has a main body  78  and a flow channel adjustment member  79 . The main body  78  has a through-hole formed along the center axis O, and a slit  781 . The slit  781  is a space formed in a central portion of the connecting member  7  in the longitudinal direction A. A proximal end portion of the hollow pipe  2  is inserted and fixed to the through-hole on the distal side of the slit  781 . According to the configuration, the connecting member  7  also advances and retracts in accordance with advancement and retraction of the slider  52 , and as a result, the hollow pipe  2  connected to the connecting member  7  advances and retracts. An opening of the proximal end of the hollow pipe  2  is opened in the slit  781 . The operation wire  9  is inserted and fixed to the through-hole on the proximal side of the slit  781 . A water discharge port  49  obtained by opening a part of a sidewall in the circumferential direction is formed in the distal end portion of the operation wire  4  for a knife. 
     The flow channel adjustment member  79  has a base part  790 , a first pipe  792 , a second pipe  794 , and a guide protrusion  793 . The first pipe  792  is a pipe located on the distal side of the base part  790 . The second pipe  794  is a pipe located on the proximal side of the base part  790 . The base part  790  has a guide surface disposed in parallel to the inner wall of the slit  781 , and a through-hole passing along the center axis O. The guide protrusion  793  protrudes in a direction substantially perpendicular to the center axis O. In this example, the pair of guide protrusions  793  are provided, and each of the guide protrusion  793  protrudes from a base part  793  in a direction different from a direction substantially perpendicular to the center axis O. 
     The first pipe  792 , the base part  790 , and the second pipe  794  are in communication with each other along the center axis O. The second pipe  794  is fixed to a distal end of the operation wire  9  for flow channel adjustment. The liquid supplied to the operation wire  9  for flow channel adjustment like the embodiment passes through the second pipe  794 , the base part  790 , and the first pipe  792 , and the liquid can be discharged from a distal opening  791  of the first pipe  792 . Further, the liquid can also be supplied into the lumen of the operation wire  4  for a knife, and the liquid passing through a space between the lumen of the operation wire  4  for a knife and the operation wire  9  for flow channel adjustment is discharged from the water discharge port  49  of the operation wire  4  for a knife. 
     The flow channel adjustment member  79  is disposed in the slit  781 . The flow channel adjustment member  79  is slidable in the slit  781  along the center axis O. 
     As shown in  FIG.  30   , the operation part  5 C according to the embodiment has a lever  55 . The operation wire  4  for a knife can advance and retract in accordance with the operation of the slider  52  of the operation part independently from the operation wire  9  for flow channel adjustment. The connecting member  7  advances and retracts in accordance with an advancing and retracting operation of the operation wire  4  for a knife. Since the hollow pipe  2  is fixed to the connecting member  7 , the hollow pipe  2  advances and retracts with respect to the sheath  1  in accordance with the operation of the operation wire  4  for a knife. The operation wire  9  for flow channel adjustment and the flow channel adjustment member  79  are provided to advance and retract with respect to the sheath  1  in accordance with the advance and retract operation of the lever  55 . The operation wire  9  for flow channel adjustment is able to advance and retract with respect to the operation wire  4  for a knife. The flow channel adjustment member  79  advances and retracts in the slit  781  of the connecting member  7  in accordance with advancement and retraction of the operation wire  9  for flow channel adjustment. At a position where the flow channel adjustment member  79  comes into contact with the proximal end in the slit  781 , the distal opening  791  of the first pipe  792  is separated from the proximal end of the hollow pipe  2  to the proximal side and is opened in the slit  781 . As shown in  FIG.  29   , at a position where the flow channel adjustment member  79  advances to the distal side in the slit  781 , the distal opening  791  of the first pipe  792  enters the flow channel  23  from the proximal end of the hollow pipe  2  and comes into contact with the flow channel  23 . 
     When the liquid is supplied into the operation wire  9  for flow channel adjustment at a position where the distal opening  791  of the first pipe  792  and the proximal end of the hollow pipe  2  are separated, the liquid flows into the proximal end of the hollow pipe  2 , and the liquid is supplied from the distal opening  22   a  of the hollow pipe  2 . When the liquid is supplied into the operation wire  9  for flow channel adjustment at the position where the distal opening  791  of the first pipe  792  and the proximal end of the hollow pipe  2  are separated, the liquid flowing in the flow channel of the hollow pipe  2  flows in the low water pressure configuration. When the liquid is supplied in a state in which the flow channel adjustment member  79  advances and the distal opening  791  of the first pipe  792  is connected to the flow channel  23  of the hollow pipe  2 , the liquid passes through the first pipe  792  having an opening area smaller than that of the flow channel  23 , the water pressure is increased, and it becomes the high water pressure configuration. When the liquid flows in the high water pressure configuration, the water force of the liquid supplied from the distal opening  22   a  of the hollow pipe  2  is increased. 
     According to the treatment tool  100 D of the embodiment, a plurality of treatments can be performed. According to the treatment tool  100 D of the embodiment, a plurality of treatment such as local injection treatment, incision peeling treatment, hemostasis treatment, additional local injection, operation site cleaning, and the like, can be performed without insertion and removal of the treatment tool  100 D from/into the channel  206  of the endoscope  200 . 
     According to the treatment tool  100 D of the embodiment, a place where the opening area is small can be provided in the flow channel  23  and the water force of the liquid can be increased by inserting the flow channel adjustment member  79  into the flow channel  23  of the hollow pipe  2 . That is, it is possible to change between the high water pressure configuration and the low water pressure configuration in accordance with a slide operation of the operation part. 
     According to the treatment tool  100 D of the embodiment, regardless of a protrusion state of the hollow pipe  2  with respect to the sheath  1 , it is possible to change between the high water pressure configuration and the low water pressure configuration. 
     Hereinabove, while the fourth embodiment has been described in detail with reference to the accompanying drawings, the specific configuration is not limited to the embodiment, and also includes design changes or the like without departing from the spirit of the present disclosure. In addition, the components shown in the above-mentioned embodiment and modified examples may be combined appropriately. While the example in which the liquid can also flow between the lumen of the operation wire  4  for a knife and the operation wire  9  for flow channel adjustment has been described in the embodiment, the configuration in which the liquid can also flow between the lumen of the operation wire  4  for a knife and the operation wire  9  for flow channel adjustment is not an essential configuration for the purpose of changing the water force of the liquid supplied from the distal opening  22   a  of the hollow pipe  2 . 
     The treatment tool  100  according to each of the embodiments includes the stepped portion  13 , and thus, upon retract of the hollow pipe  2 , the flange  21  can be accommodated in the stepped portion  13 . While the example in which the stepped portion  13  is formed in the distal end of the pipe holder  11  has been described in the above-mentioned embodiment, the stepped portion  13  is not an essential configuration for the purpose of adjusting the water force of the liquid supplied. 
     While some embodiments of the disclosure have been described and illustrated above, it should be understood that these are exemplary of the disclosure and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present disclosure. Accordingly, the disclosure is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.