Patent Publication Number: US-2009221969-A1

Title: Device and medical instrument for preventing excessive insertion of a rod-like member

Description:
FIELD OF THE INVENTION 
     The present invention relates to a device for preventing excessive insertion which is used when a rod-like member is inserted into a gastrostomy catheter which is positioned in a fistula formed in a patient&#39;s body, and to a medical instrument provided with the same. 
     BACKGROUND OF THE INVENTION 
     It is conventional practice to position a gastrostomy catheter in a fistula formed in a patient&#39;s body, and to insert an endoscope into the gastrostomy catheter to observe the inside of the stomach as well as to confirm the position of the gastrostomy catheter. In such cases, it is necessary to change the orientation of the tip end of the endoscope so as to be able to see in various directions in order to accurately confirm the state of the inside of the stomach and position of the gastrostomy catheter. Consequently, a bending instrument or the like which can change the orientation of the tip end of the endoscope is used when the endoscope is inserted a prescribed length into the gastrostomy catheter. In such cases, if more than is necessary of the endoscope is inserted into the stomach from the gastrostomy catheter, the bent portion of the endoscope grows larger, making it impossible to make accurate observations. Additionally, the endoscope may be damaged. 
     In order to prevent this, it has been envisaged to prevent the endoscope from being inserted beyond a prescribed length into the gastrostomy catheter using a stopper, or the like (see Japanese Unexamined Utility Model Registration Application H1-130317, for example). The laser probe disclosed in H1-130317 consists of a probe main body in which an optical fiber serves as a light guide. The probe main body has a configuration in which it is inserted into the endoscope for use. A stopper or the like is then fixed to a prescribed portion of the probe main body, and it is possible to regulate the probe main body by means of the stopper so that it is not inserted more than necessary into the endoscope. 
     However, with the laser probe mentioned above, when the probe main body is inserted into endoscopes of different lengths, the length of the tip end portion of the probe main body which projects from the tip end of the endoscope may be too great or too small. Consequently, when the laser probe is inserted into the stomach via the gastrostomy catheter, the tip end of the laser probe cannot be inserted into the stomach to a suitable length in accordance with the length of the gastrostomy catheter. Furthermore, it is not just the endoscope which is inserted into the gastrostomy catheter, but also a push-rod, for example, for making the stomach-internal fixed part extend in an elongate fashion when the gastrostomy catheter is positioned in the fistula formed in the body of the patient. Here too it is necessary to insert the push-rod to a suitable length in accordance with the length of the gastrostomy catheter. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a device is used for preventing excessive insertion when a rod-like member is inserted into a gastrostomy catheter comprising a tubular part and a stomach-internal fixed part. The fixed part comprises an expanded body which links with a tip end of the tubular part. The tip end is provided with a through-hole, and said fixed part extends in an elongate fashion due to a portion on a through-hole side being pushed in the direction of a tip end side. The device generally comprises a reference position establishment part which can be installed at a prescribed portion on a base end opening side of the gastrostomy catheter in a state in which it can move in a longitudinal direction of the rod-like member. A mobile part can be fixed to a prescribed portion of the rod-like member. A linking part can change a gap between the reference position establishment part and the mobile part within a range which is no greater than a set length, and links the reference position establishment part and the mobile part. 
     In another aspect of the present invention, a medical instrument in combination with the device described in the preceding paragraph. 
     Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a gastrostomy catheter, where (a) is a plan view, (b) is a front view, and (c) is a bottom view. 
         FIG. 2  is a front view showing a state in which the device for preventing excessive insertion according to the first embodiment of the present invention is fitted to an endoscope. 
         FIG. 3  is a front view showing the endoscope. 
         FIG. 4  shows the device for preventing excessive insertion according to the first embodiment of the present invention, where (a) is a plan view, (b) is a front view, (c) is a side view, and (d) is a bottom view. 
         FIG. 5  shows a state in which the mobile part of the device for preventing excessive insertion according to the first embodiment has moved to the reference position establishment part side, where (a) is a front view, and (b) is a side view. 
         FIG. 6  is an oblique view showing a bending instrument. 
         FIG. 7  is a fragmentary cutaway in cross section showing a state in which the endoscope, to which the device for preventing excessive insertion according to the first embodiment is fitted, is positioned above the gastrostomy catheter in the patient&#39;s body. 
         FIG. 8  is a fragmentary cutaway in cross section showing a state in which the endoscope, to which the device for preventing excessive insertion according to the first embodiment is fitted, is inserted into the gastrostomy catheter in the patient&#39;s body. 
         FIG. 9  is a fragmentary cutaway in cross section showing a state in which the position of the gastrostomy catheter is confirmed using the endoscope to which the device for preventing excessive insertion according to the first embodiment is fitted. 
         FIG. 10  shows the device for preventing excessive insertion according to a second embodiment of the present invention, where (a) is a plan view, (b) is a front view, and (c) is a bottom view. 
         FIG. 11  is a fragmentary cutaway in cross section showing a state in which the endoscope, to which the device for preventing excessive insertion according to the second embodiment is fitted, is inserted in the gastrostomy catheter in the patient&#39;s body. 
         FIG. 12  is a fragmentary cutaway in cross section showing a state in which the position of the gastrostomy catheter is confirmed using the endoscope to which the device for preventing excessive insertion according to the second embodiment is fitted. 
         FIG. 13  is a front view showing the device for preventing excessive insertion according to a third embodiment of the present invention. 
         FIG. 14  is a front view showing a state in which the linking part of the device for preventing excessive insertion according to the third embodiment of the present invention is in a contracted state. 
         FIG. 15  is a fragmentary cutaway in cross section showing a state in which the endoscope, to which the device for preventing excessive insertion according to the third embodiment is fitted, is inserted in the gastrostomy catheter in the patient&#39;s body. 
         FIG. 16  is a fragmentary cutaway in cross section showing a state in which the position of the gastrostomy catheter is confirmed using the endoscope to which the device for preventing excessive insertion according to the third embodiment is fitted. 
         FIG. 17  shows the device for preventing excessive insertion according to a fourth embodiment of the present invention, where (a) is a plan view, (b) is a front view, and (c) is a bottom view. 
         FIG. 18  is an oblique view showing the fitting instrument which is used according to the fourth embodiment of the present invention. 
         FIG. 19  is a front view showing a state in which the push-rod of the fitting instrument to which the device for preventing excessive insertion according to the fourth embodiment is attached is inserted in the gastrostomy catheter. 
         FIG. 20  is a front view showing a state in which the stomach-internal fixed part of the gastrostomy catheter is extended using the fitting instrument to which the device for preventing excessive insertion according to the fourth embodiment is attached. 
         FIG. 21  is a fragmentary cutaway in cross section showing a state in which the stomach-internal fixed part of the gastrostomy catheter has entered the stomach by means of the fitting instrument to which the device for preventing excessive insertion according to the fourth embodiment is attached. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the present invention is described below using the figures.  FIG. 1  shows a gastrostomy catheter  10  pertaining to the first embodiment.  FIG. 2  shows a state in which a device  30  for preventing excessive insertion, a bending instrument  40 , and an insertion aid  50  etc. are fitted to an endoscope  20  which acts as the rod-like member according to the present invention which is inserted into the gastrostomy catheter  10 . The medical instrument according to the first embodiment comprises the gastrostomy catheter  10 , endoscope  20 , device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50 , among other things. The gastrostomy catheter  10  consists of an external fixed part  11 , a tubular part  12  which is linked to the centre of the lower surface of the external fixed part  11 , and a stomach-internal fixed part  13  which is attached to the lower end of the tubular part  12 . All the components are made of a soft plastic material such as polyurethane or silicone. 
     In the description that follows, the external fixed part  11  will be referred to as the upper side, and the stomach-internal fixed part  13  will be referred to as the lower side. The external fixed part  11  comprises an insertion opening  11   a  which is annular and fairly thick, and projecting pieces  11   b ,  11   c  which project at both sides from the lower end of both side parts of the insertion opening  11   a . The outline of the portion including the projecting pieces  11   b ,  11   c  and the insertion opening  11   a  is elliptical, when seen as a plane, and the function of these projecting pieces  11   b ,  11   c  is to prevent the gastrostomy catheter  10  from being pulled into the stomach S (see  FIGS. 7 to 9 ). A valve body  14   a  which is formed with a central slit is then provided on the inner peripheral surface of an insertion hole  14  which is formed in the centre of the insertion opening  11   a , passing through vertically. Furthermore, an engagement groove is formed along the circumference at the upper side of the valve body  14   a  on the inner peripheral surface of the insertion hole  14 , although this is not depicted. 
     A cover part  15  for closing off the insertion hole  14  of the insertion opening  11   a  is then joined to the tip end of the projecting piece  11   b . The cover part  15  comprises an elongate strip-shaped linking part  15   a  which is linked to the end of the projecting piece  11   b , and a broad part  15   b  which is shorter and wider than the strip-shaped linking part  15   a , and is formed at the tip end of the strip-shaped linking part  15   a . A stopper part  16  shaped like a column which is short in the axial direction is then provided on the broad part  15   b . The strip-shaped linking part  15   a  is flexible, and it can flex so as to vertically rotate, or bend at a sharp angle, with the linking part to the projecting piece  11   b  at the centre. The stopper part  16  is provided on the strip-shaped linking part  15   a  side portion of the broad part  15   b , so as to face the insertion hole  14  when the strip-shaped linking part  15   a  is bent to position the broad part  15   b  above the insertion opening  11   a.    
     The stopper part  16  is formed with a columnar shape which can fit into the insertion hole  14 , and it is provided on its outer peripheral surface with an annular projection  16   a  running along its periphery, the projection being able to detachably engage with the engagement groove formed on the inner peripheral surface of the insertion hole  14 . Accordingly, it is possible to engage the engagement groove with the annular projection  16   a  by bending the strip-shaped linking part  15   a  so that it is upwardly inverted, and pushing the stopper part  16  into the insertion hole  14 , and this makes it possible to close off the insertion hole  14  of the insertion opening  11   a  in an airtight and liquid-tight manner. It is also possible to open the insertion hole  14  of the insertion opening  11   a  by pulling the broad part  15   b  to release the fitting between the stopper part  16  and the insertion hole  14 . 
     The tubular part  12  is formed as a cylindrical shape, and a through-orifice (not depicted) for allowing the passage of fluids such as nutrients and food in fluid form is formed inside it; the upper end of the through-orifice links in communication with the insertion hole  14  of the external fixed part  11 . The stomach-internal fixed part  13  is connected to the tubular part  12  via a connection part  17  which is fixed to the lower end of the tubular part  12 . The connection part  17  is formed as a cylinder for covering the outer peripheral surface of the tubular part  12  and is integrally formed with the stomach-internal fixed part  13 . The connection part  17  is fixed to the lower end of the tubular part  12 , in a state in which it cannot be removed from the tubular part  12 . 
     The stomach-internal fixed part  13  comprises four strip-shaped linking parts  13   a  which are linked to the edge of a lower end opening of the connection part  17  and extend in four directions, four linking film parts  13   b  which are provided between the upper parts of each of the linking parts  13   a  and form a substantially dome-shaped stomach wall contact part with the four linking parts  13   a , and a converging part  13   c  where the tip ends of all of the linking parts  13   a  converge. The four linking parts  13   a  comprise strip-shaped members which are bent into substantially semi-circular shapes which split into four directions from the lower end of the connection part  17 , respectively extending downwards from the horizontal, after which they converge below the central axis of the tubular part  12 , linking to form the converging part  13   c . In other words, the converging part  13   c  allows each of the linking parts  13   a  to link by joining the lower ends of all of the linking parts  13   a , and it is also positioned by all of the linking parts  13   a  below the central axis of the tubular part  12 . 
     Moreover, the stomach-internal fixed part  13  which comprises the linking parts  13   a , linking film parts  13   b  and the converging part  13   c  is integrally formed together with the connection part  17 . Furthermore, all of the linking parts  13   a  and linking film parts  13   b  are made of a soft, flexible, elastic material, and the overall flat, substantially spherical shape is normally maintained by means of its elasticity, as shown in  FIG. 1 . The linking parts  13   a  and linking film parts  13   b  can then be extended to make them straight and elongate by pulling the converging part  13   c  downwards. Furthermore, the lower end of the through-orifice of the tubular part  12  opens between the upper ends of the linking parts  13   a.    
     Spaces formed between the lower parts of each of the linking parts  13   a  then form channels for the passage of fluids such as nutrients and food in fluid form sent out from the through-hole of the tubular part  12  into the stomach S. A through-hole  18  is additionally formed in the centre of the converging part  13   c , and a cylindrical engagement part  18   a  (see  FIGS. 7 to 9 ) is formed at the upper part of the through-hole  18  (converging part  13   c ). Hence, the through-hole  18  is configured by the inner peripheral surface of the cylindrical engagement part  18   a , and its diameter is smaller than the diameter of the insertion hole  14  of the external fixed part  11  and the diameter of the through-orifice of the tubular part  12 . The stomach-internal fixed part  13  configured in this manner is positioned on the inner surface of the patient&#39;s stomach wall SW (see  FIGS. 7 to 9 ) and its function is to prevent the gastrostomy catheter  10  from being removed from the patient&#39;s body. 
     As shown in  FIG. 3 , the endoscope  20  has a configuration in which a lens  22  is attached to the tip end of a shaft  21 , and a connection part  23  is attached to the rear end thereof. The shaft  21  consists of a bundle of fibres comprising a plurality of light guides (not depicted) for irradiating light onto the stomach wall SW, and an image guide (not depicted) for sending reflected light via the lens, and it is flexible. The connection part  23  is linked to wiring  24  which connects the image guide to an image display device (not depicted), and to wiring  25  which connects the light guides to a light source device (not depicted). The lens  22  sends images obtained by the irradiated light to the image display device via the image guide and the wiring  24 . 
     Hence, the light guides irradiate the inner surface of the stomach wall SW with light sent from the light source device to make observation possible, and the image guide sends the light which is reflected from the inner surface of the stomach wall SW and focused by means of the lens  22  to the image display device. The image display device then enlarges the images based on the reflected light sent and displays them on an image display part provided in the image display device. Furthermore, as shown in  FIG. 2 , the shaft  21  is covered by a sheath  26 , and it is possible to prevent soiling of the shaft by covering it with the sheath  26 . The sheath  26  consists of a tube in which the tip end is closed off by a light-transmissive window part (not depicted), and in which the diameter of the base end  26   a  on the opening side is somewhat larger than the other portion, and it is flexible. 
     The sheath  26  is formed with a thickness such that it can cover the shaft  21  in a state in which it is in close contact with the outer peripheral surface of the shaft  21 , and it is attached to the shaft  21  by pushing the tip-end narrow-diameter part  23   a  of the connection part  23  into the base end  26   a . The sheath  26  is prevented from being removed from the shaft  21  using a member such as a clamp, a fastener, a clasp or the like. When assembled in this state, a configuration is adopted so that the lens  22  is in contact with the inner surface of the window part. Furthermore, the surface of the window part forms a curving protrusion which projects downwards. 
     As shown in  FIG. 4 , the device  30  for preventing excessive insertion consists of a reference position establishment part  31 , a mobile part  32  and a linking part  33 . The reference position establishment part  31  consists of an annular body in the centre of the disc of which is formed a through-hole  34  through which the shaft  21  which is covered by the sheath  26  can pass with clearance. The mobile part  32  consists of a mobile part main body  35  which is formed with plane parts in which both the left- and right-hand portions of the disc (the left- and right-hand side portions in the states shown in  FIGS. 4(   a ) and ( b )) have been cut away, these plane parts running parallel to each other on both the left- and right-hand sides, and guide screws  36  which are each attached to the plane parts of the mobile part main body  35 . 
     Furthermore, the diameter at the centre of the mobile part main body  35  is smaller than the through-hole  34 , but a through-hole  37  through which the shaft  21  covered by the sheath  26  can pass is formed therein. Screw holes are formed from the centre of both plane parts of the mobile part main body  35  towards the inner peripheral surface of the through-hole  37 , and the guide screws  36  screw into these screw holes. When one end of the guide screws  36  is positioned on the inner peripheral surface of the through-hole  37 , the other end of the guide screws reaches a state in which it protrudes outwards from the plane parts, and one end of the guide screws  36  can be made to project into the through-hole  37  by turning the guide screws  36  in one direction. 
     The linking part  33  is integrally formed with the reference position establishment part  31 , and consists of a pair of rail-like guiding pieces  38  which run vertically. The outline of the guide pieces  38  has a shape seen from above in which both arcuate end parts are joined by a straight line, and seen from the front they are arranged laterally symmetrically, comprising members formed as a longitudinal frame with a gap between them. Hence, when the mobile part main body  35  has been positioned between the pair of guide pieces  38  in a state in which the plane parts of the mobile main body  35  and the plane parts of the guide pieces  38  are aligned, the pair of guide pieces  38  is formed so that the outline is circular when seen from above. Consequently, the mobile part main body  35  can slide vertically between the pair of guide pieces  38  in a state in which the axial rotation thereof is controlled. 
     Furthermore, opposing guide holes  39  are formed in the centre of the two guide pieces  38 , running vertically. These guide holes  39  have a width enabling the guide screws  36  of the mobile part  32  to be positioned inside in a mobile fashion. The mobile part  32  is arranged between the pair of guide pieces  38  in a state in which the two guide screws  36  are positioned inside the guide holes  39  of the respectively opposing guide pieces  38 , and the mobile part is prevented from being removed from the linking part  33  by the engagement of the guide screws  36  with the peripheral edge of the guide holes  39 .  FIG. 5  shows a state in which the mobile part  32  has moved to the lower end of the linking part  33 , and the mobile part  32  can be moved between the position shown in  FIGS. 4(   b ) and ( c ) and the position shown in  FIG. 5 . The maximum length which the mobile part  32  can move along the guide holes  39  is the set length pertaining to the present invention. 
     The bending instrument  40  is used to bend the tip end portion of the shaft  21  of the endoscope  20  so as to change the direction of observation of the endoscope  20 . As shown in  FIG. 6 , the bending instrument  40  consists of a cylindrical fixed part  41 , a cylindrical stepped sliding part  42  which is longer in the axial direction than the fixed part  41 , and a linear linking part  43  which links the fixed part  41  and the sliding part  42 . The fixed part  41  consists of a cylindrical body in which the diameter of the lower portion tapers to become somewhat smaller than the diameter of the upper portion. The inner diameter of the upper portion of the fixed part  41  is somewhat greater than the outer diameter of the sheath  26 , and the inner diameter of the lower end part of the fixed part  41  is somewhat smaller than the outer diameter of the sheath  26 . Furthermore, the outer diameter of the upper portion of the fixed part  41  is smaller than the diameter of the through-hole  18  of the stomach-internal fixed part  13 . 
     Consequently, the fixed part  41  can penetrate into the gastrostomy catheter  10  from the insertion hole  14  towards the through-hole  18 . Furthermore, when the sheath  26  is inserted into the fixed part  41  from the upper part towards the lower part from the tip end, the outer peripheral part of the tip end of the sheath  26  abuts the inner peripheral part at the lower end of the fixed part  41 . Consequently, the sheath  26  cannot pass through inside the fixed part  41  and it is in a state in which it covers the shaft  21 . Moreover, when the bending instrument  40  is being used, the fixed part  41  is fixed to the outer peripheral part of the tip end of the sheath  26  by means of adhesive. 
     The inner diameter of the sliding part  42  is somewhat greater than the outer diameter of the sheath  26 , and when the sheath  26  passes through the sliding part  42 , the sliding part  42  is able to slide along in the length direction of the sheath  26 . Furthermore, a latch part  44  which has a greater diameter than the lower portion of the sliding part  42  is formed at the upper part of the sliding part  42 . The latch part  44  is formed with a shape which tapers upwards in which the outer diameter at the upper portion is smaller than the outer diameter at the lower portion. A step part  45  having a horizontal surface is then formed at the lower end of the latch part  44 . 
     The outer diameter of the step part  45  is smaller than the diameter of the insertion hole  14  of the external fixed part  11  and of the through-hole of the tubular part  12 , but greater than the diameter of the through-hole  18  of the stomach-internal fixed part  13 . Consequently, when the bending instrument  40  is inserted into the gastrostomy catheter  10  from the insertion hole  14  towards the through-hole  18 , the bending instrument  40  passes through the insertion hole  14  of the external fixed part  11  and the through-hole of the tubular part  12 . The lower portion of the sliding part  42  then also passes through the through-hole  18  of the stomach-internal fixed part  13 , but when the step part  45  reaches the cylindrical engagement part  18   a , the step part  45  and the cylindrical engagement part  18   a  engage, and the latch part  44  cannot pass through the through-hole  18 . 
     Furthermore, the linear linking part  43  is flexible and links the upper end edge of the fixed part  41  and the portion opposite at the lower end edge of the sliding part  42 . After the shaft  21  of the endoscope  20  has passed inside the bending instrument  40  together with the sheath  26 , and the outer peripheral part of the tip end of the sheath  26  has engaged with the inner peripheral part at the lower end of the fixed part  41 , when the sheath  26  etc. are inserted, the direction in which the tip end of the endoscope  20  is oriented can be changed by bending the linear linking part  43 . The linear linking part  43  is positioned on the inner peripheral side when the shaft  21  etc. is bent, and it keeps the distance between the upper end edge of the fixed part  41  and the lower end edge of the sliding part  42  substantially constant. 
     The insertion aid  50  is attached to the gastrostomy catheter  10  to provide smoother insertion of the endoscope  20  etc. into the gastrostomy catheter  10 , and it consists of a connection part  51 , insertion opening  52  and an air supply opening  53 . The connection part  51  consists of a substantially cylindrical engagement part  55  which is formed in the centre of the lower surface of an annular connection part main body  54 , and a through-hole for allowing the insertion of the shaft  21  covered by the sheath  26  is formed therein. Furthermore, the connection part main body  54  is formed with an annular shape which is somewhat smaller than the insertion opening  11   a  of the gastrostomy catheter  10 , and the engagement part  55  is formed with a cylindrical shape having four different levels. 
     The engagement part  55  is made up of an uppermost level in which the outer peripheral surface which has a larger diameter at its upper part than its lower part has an oblique surface, a second level which has the same diameter as the lower part of the uppermost level, a third level which has substantially the same diameter as the upper part of the uppermost level, and a lowermost level in which the outer peripheral surface which has substantially the same diameter as the second level at its upper part, and a smaller diameter at its lower part than its upper part has an oblique surface. The third level of the engagement part  55  configures an annular projection  56  which is able to detachably engage with the engagement groove formed in the insertion hole  14  of the gastrostomy catheter  10 , and when the annular projection  56  engages with the engagement groove, a state of air-tightness and liquid-tightness is achieved between the engagement part  55  and the peripheral surface of the insertion hole  14 . 
     The insertion opening  52  is formed with a cylindrical shape and an insertion hole enabling the insertion of the shaft  21  covered by the sheath  26  is formed therein, an annular reinforcing rib  57  being formed on the edge of the opening at the upper end. Furthermore, the through-hole formed inside the insertion opening  52  and the insertion hole formed inside the connection part  51  have the same diameter and are also coaxially linked in communication. The air supply opening  53  is formed as a cylindrical shape extending obliquely upwards from the side at the lower end of the insertion opening  52  in a state in which it is inclined at approximately 45° to the insertion opening  52 , and it is narrower in diameter than the insertion opening  52 . An annular reinforcing rib  58  is furthermore formed on the edge of the opening at the upper end of the air supply opening  53 . 
     An air supply device (not depicted) is connected to the reinforcing rib  58  of the air supply opening  53 , and air which is supplied from the air supply device passes through inside the air supply opening  53  and is sent to the lower end inside the insertion opening  52 . Furthermore, an airflow channel (not depicted) for allowing the passage of air is formed between the lower end inside the insertion opening  52  and the lower end inside the connection part  51 ; air sent to the lower end inside the insertion opening  52  is released to the outside from the lower end of the connection part  51 . A substantially triangular sheet-like reinforcing grip part  59  for strengthening the area between the insertion opening  52  and the air supply opening  53  and also for facilitating holding of the insertion aid  50  with the hand is formed between the insertion opening  52  and the air supply opening  53 . 
     A description of the method of confirming the position of the gastrostomy catheter  10  using the endoscope  20 , sheath  26 , device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50  configured in the manner described above will be given next, with reference to  FIGS. 7 to 9 .  FIG. 7  shows a state in which the gastrostomy catheter  10  is positioned in a fistula provided in the abdominal wall AW and the stomach wall SW of a patient, where the gastrostomy catheter  10  is positioned in the fistula using an instrument for fitting it which will be described later. In the state shown in  FIG. 7 , the stopper part  16  of the gastrostomy catheter  10  is removed from the insertion hole  14  to open the upper end of the insertion hole  14 . Furthermore, the endoscope  20  to which are fitted the sheath  26 , device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50  is positioned above the gastrostomy catheter  10 . 
     The endoscope  20  and other components which are in this state are moved down in the direction of the arrow in the figures so that the shaft  21  projecting from the lower end of the insertion aid  50  is inserted into the insertion hole  14  of the gastrostomy catheter  10  together with the sheath  26  and bending aid  40 . At this time, an operator holds both sides of the insertion opening  11   a  where the projecting pieces  11   b ,  11   c  are not formed on the gastrostomy catheter  10  with one hand, and holds the insertion aid  50  with the other hand, and pushes the insertion aid  50  into the gastrostomy catheter  10 . As shown in  FIG. 8 , this makes it possible to engage the insertion aid  50  with the gastrostomy catheter  10 . 
     The engagement is brought about by the engagement of the engagement part  55  of the insertion aid  50  with the engagement groove of the gastrostomy catheter  10 , and a state of air-tightness and liquid-tightness is achieved between the insertion aid  50  and the gastrostomy catheter  10 . In this state, the endoscope  20  is then further inserted towards the lower side of the gastrostomy catheter  10  together with the sheath  26  and bending instrument  40 . This operation is carried out while the operator is looking at the image display part of the image display device, and insertion of the endoscope  20  and other members is stopped when the tip end of the endoscope  20  has reached the cylindrical engagement part  18   a , and the device  30  for preventing excessive insertion is fixed to the shaft  21  with the sheath  26  interposed. 
     The mobile part  32  is positioned at the upper end of the guide holes  39  of the linking part  33 , in a state in which the reference position establishment part of the device  30  for preventing excessive insertion is in abutment with the reinforcing rib  57  of the insertion aid  50 . The guide screws  36  are then turned so that the shaft  21  which is positioned inside the mobile part main body  35  is pressured, via the sheath  26 , at its tip end. By means of this, the mobile part  32  is fixed to the shaft  21 . Moreover, after the insertion aid  50  has been connected to the gastrostomy catheter  10 , the shaft  21  and the bending instrument  40  etc. can pass through the insertion aid  50 . Furthermore, engaging parts which can be detached from each other may be provided between the reference position establishment part  31  of the device  30  for preventing excessive insertion and the reinforcing rib  57  of the insertion aid  50 . 
     Next, air is supplied from the air supply device to inside the air supply opening  53 , and the air is sent into the stomach S from the connection part  51  via the tubular part  12  of the gastrostomy catheter  10 . This allows the stomach S to expand, as shown in  FIG. 9 . The respective areas between the gastrostomy catheter  10  and the insertion aid  50 , and between the insertion aid  50  and the sheath  26  are closed off, and therefore the air inside the stomach S does not leak outside. Light which is generated by means of the light source device then passes through the wiring  25  and the light guides of the shaft  21 , and is irradiated towards the stomach wall SW. Furthermore, the portion at the lower part of the shaft  21  can be made to flex together with the sheath  26  so that it is possible to change the position of irradiation of the stomach wall SW, and this is achieved by pushing the shaft  21  and the sheath  26  etc. further into the body, as shown in  FIG. 9 . 
     The mobile part  32  of the device  30  for preventing excessive insertion gradually comes closer to the reference position establishment part  31 , and the position of irradiation of the stomach wall SW by the light guides moves upwards from below in accordance with this. At this time, the whole surface of the stomach wall SW can be irradiated by the light guides by turning the shaft  21  etc. in the axial direction. Then, when the mobile part  32  is in abutment with the reference position establishment part  31 , the shaft  21  etc. cannot be pushed any further into the body. By means of this, the shaft  21  etc. is prevented from being inserted more than necessary into the stomach S. 
     In this way, by means of this medical instrument, the position of irradiation of the stomach wall SW by the light guides can be changed between the state shown in  FIG. 8  in which the shaft  21 , sheath  26  and bending instrument  40  extend straight ahead, and the state shown in  FIG. 9  in which the shaft etc. is bent. When the shaft  21  etc. is pulled more with respect to the bending instrument  40  from the state shown in  FIG. 8 , the fixed part  41  of the bending instrument  40  and the portion at the lower part of the sliding part  42  pass through the through-hole  18  of the stomach-internal fixed part  13  and enter the stomach S, but the latch part  44  engages with the cylindrical engagement part  18   a  of the through-hole  18  and is held inside the stomach-internal fixed part  13 . 
     Consequently, the fixed part  41  moves so as to describe the arc of a circle, with the linear linking part  43  as the radius, and the tip end portion of the shaft  21  and the sheath  26  follow this movement of the fixed part  41  while bending, and protrude inside the stomach S. The range shown by the two-dot chain line a in  FIG. 9  shows the range of light irradiation by the light guides. Light which is irradiated by means of the light guides and reflected off the stomach wall SW is focused by the lens  22 , after which it is sent to the image display device by way of the image guide and the wiring  24  of the shaft  21 . 
     Images which are sent to the image display device are enlarged in the image display part of the image display device and displayed, and therefore it is possible to confirm whether or not the stomach-internal fixed part  13  of the gastrostomy catheter  10  is positioned in the correct state inside the stomach S, from the images displayed in the image display part. If it is possible to confirm that the gastrostomy catheter  10  is positioned in the correct state, an operation is carried out in which the endoscope  20  is removed from the gastrostomy catheter  10  together with the sheath  26 , bending instrument  40  and insertion aid  50 , and also the sheath  26 , device  30  for preventing excessive insertion, the bending instrument  40  and the insertion aid  50  are removed from the shaft  21 . 
     In this operation, the endoscope  20  is first of all pulled slightly upwards together with the sheath  26 , device  30  for preventing excessive insertion, and bending instrument  40 , and then in the state shown in  FIG. 8 , the engagement between the engagement part  55  of the insertion aid  50  and the engagement groove of the gastrostomy catheter  10  is released. At this time, the mobile part  32  of the device  30  for preventing excessive insertion gradually moves away from the reference position establishment part  31  and is positioned at the upper end of the guide holes  39  of the linking part  33 . The endoscope  20  is then removed from the gastrostomy catheter  10  by pulling it upwards together with the sheath  26 , device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50 . In addition, the device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50  are removed from the sheath  26 , after which the shaft  21  is pulled out of the sheath  26 . The guide screws  36  of the mobile part  32  are loosened. 
     The sheath  26  and the bending instrument  40  are then disposed of, and the endoscope  20  can be reused next time. Furthermore, if the device  30  for preventing excessive insertion and the insertion aid  50  are not soiled by gastric juices or the like, they can be reused next time. At this time, the shaft  21  and the lens  22  of the endoscope  20  do not come into contact with the liquids and residues inside the patient&#39;s body and stomach S, so they are not soiled and there is no need for the most part to clean or sterilize them. Moreover, in the operation described above, the engagement between the engagement part  55  of the insertion aid  50  and the engagement groove of the gastrostomy catheter  10  is released, and the endoscope  20  is removed from the gastrostomy catheter  10  together with the bending instrument  40  and the insertion aid  50 , but it is also possible to remove the endoscope  20  etc. from the insertion aid  50 , and then to release the engagement between the engagement part  55  of the insertion aid  50  and the engagement groove of the gastrostomy catheter  10 . 
     Furthermore, when nutrient fluid is supplied to the patient&#39;s stomach S, for example, by way of the gastrostomy catheter  10  which is positioned in the patient&#39;s body, a connector for a tube extending from a container housing the nutrients is connected to the insertion hole  14  of the gastrostomy catheter  10 . In this state, nutrients are supplied to the patient by way of the tube and the gastrostomy catheter  10 . At this time, nutrients coming out of the tubular part  12  pass from the stomach-internal fixed part  13  through each of the linking parts  13   a , and enter the stomach S. Furthermore, after use, the tube from the container of nutrients is removed from the insertion hole  14  of the gastrostomy catheter  10 , and the insertion hole  14  is closed using the stopper part  16 . Then, when it becomes necessary to replace the gastrostomy catheter  10  after a prescribed period of use, it can be replaced with a new gastrostomy catheter  10 . Here too, the position of the gastrostomy catheter  10  in the fistula can be confirmed using the endoscope  20 , device  30  for preventing excessive insertion, bending instrument  40  and insertion aid  50  which have been described above. 
     In this way, the device  30  for preventing excessive insertion according to this embodiment consists of the reference position establishment part  31 , mobile part  32 , and linking part  33 , and the linking part  33  can change the gap between the reference position establishment part  31  and the mobile part  32  within a range which is no greater than a set length. Consequently, when the position of the gastrostomy catheter  10  is confirmed using the endoscope  20  provided with the bending instrument  40 , the tip end portion of the endoscope  20  bends suitably in a feasible range so as to be able to observe the whole of the inside of the stomach S. 
     In other words, when the position of the gastrostomy catheter  10  is confirmed, if the endoscope  20  to which the device  30  for preventing excessive insertion etc. is attached is inserted from the insertion hole  14 , the tip end portion of the endoscope  20  gradually bends, and the mobile part  32  abuts the reference position establishment part  31  at the point where the whole of the inside of the stomach S can be observed by the endoscope  20 , and the mobile part  32  cannot move any further. By this means, the endoscope  20  cannot be inserted any further either, and therefore it is possible to prevent the endoscope  20  from being inserted more than necessary into the stomach S. As a result, it is possible to prevent the bending portion of the endoscope  20  from increasing in size, which makes accurate observation impossible, and to prevent damage to the endoscope  20 . 
       FIG. 10  shows a device  60  for preventing excessive insertion according to a second embodiment of the present invention. The device  60  for preventing excessive insertion consists of a reference position establishment part  61 , a mobile part  62  and a linking part  63 . The reference position establishment part  61  consists of an elastic plate which is substantially C-shaped when viewed from above, and a through-hole  64  which is formed in the centre is of a size that enables the shaft  21  covered by the sheath  26  to pass through with clearance. The mobile part  62  consists of an elastic plate which is substantially C-shaped when viewed from above, and a through-hole  67  which is formed in the centre is of a size that enables it to fasten onto the shaft  21  covered by the sheath  26 . 
     The linking part  63  links the reference position establishment part  61  to the mobile part  62  due to the fact that it is formed as a single piece with the reference position establishment part  61  and the mobile part  62 , and it consists of a narrow, flexible linear part which runs vertically. The reference position establishment part  61  and the mobile part  62  are both flexible, and the gap between both ends can be enlarged so that the shaft  21  covered by the sheath  26  can be inserted into the respective through-holes  64 ,  67 , by pushing the area between both ends with the outer peripheral surface of the shaft  21  covered by the sheath  26 . 
     At this time, the reference position establishment part  61  can move in the axial direction of the shaft  21 , and the mobile part  62  is fixed to the shaft  21 . Consequently, the reference position establishment part  61  and the mobile part  62  can advance and retract with respect to each other within a range that is no greater than the length of the linking part  63 . In other words, with the device  60  for preventing excessive insertion, the length of the linking part  63  is the set length pertaining to the present invention. The structural components of the medical instrument provided with the device  60  for preventing excessive insertion other than the device  60  for preventing excessive insertion are the same as those for the medical instrument provided with the device  30  for preventing excessive insertion, other than the device  30  for preventing excessive insertion. 
     When the position of the gastrostomy catheter  10  is confirmed by means of the endoscope  20  using the device  60  for preventing excessive insertion configured in the manner described above, the endoscope  20  to which are attached the sheath  26 , bending instrument  40  and insertion aid  50  is first of all positioned above the gastrostomy catheter  10 . The endoscope  20  and other components in this state are moved down and then insertion of the endoscope  20  etc. is stopped at the point where it has been ascertained on the image display part of the image display device that the tip end of the endoscope  20  has reached the cylindrical engagement part  18   a . In this state, an operation is carried out to attach the device  60  for preventing excessive insertion to the shaft  21 , with the sheath  26  interposed. 
     The reference position establishment part  61  is attached to the shaft  21  by first of all bringing the reference position establishment part  61  of the device  60  for preventing excessive insertion into abutment with the upper surface of the reinforcing rib  57  of the insertion aid  50  so that the area between both ends of the reference position establishment part  61  are pressed by the shaft  21 . Next, with the linking part  63  extending straight ahead vertically, the mobile part  62  is fixed to the shaft  21  by pressing the area between the two end parts of the mobile part  62  with the shaft  21 , and the state shown in  FIG. 11  is reached. Next, the stomach S is expanded by sending air into the stomach S, after which the shaft  21  etc. is pushed further into the body. 
     By means of this, as shown in  FIG. 12 , the portion at the lower part of the shaft  21  bends together with the sheath  26  so that the position of irradiation of the stomach wall SW by the light guides can be changed. Here too, the mobile part  62  gradually moves closer to the reference position establishment part  61 , and the position of irradiation of the stomach wall SW by the light guides moves upwards from below in accordance with this. At this time, the linking part  63  bends and projects outwards. Here too, the whole surface of the stomach wall SW can be irradiated by the light guides by turning the shaft  21  etc. in the axial direction. Then, when the mobile part  62  is in abutment with the reference position establishment part  61 , the shaft  21  etc. cannot be pushed any further into the body. By this means, the shaft  21  etc. is prevented from being inserted more than necessary into the stomach S. 
     According to the device  60  for preventing excessive insertion, the linking part  63  can be endowed with a simple configuration. Furthermore, when the shaft  21  is inserted into the gastrostomy catheter  10 , the operation to turn the shaft in the axial direction is simple. Furthermore, when the shaft  21  is inserted into the gastrostomy catheter  10 , the length of insertion of the shaft  21  is determined at the point when the mobile part  62  is fixed to the shaft  21 , even if the reference position establishment part  61  is separated from the reinforcing rib  57  of the insertion aid  50 , and therefore there are no difficulties unless the reference position establishment part  61  and mobile part  62  are removed from the shaft  21 . The other operational effects of the device  60  for preventing excessive insertion and the medical instrument provided with the device  60  for preventing excessive insertion are the same as the device  30  for preventing excessive insertion and the medical instrument provided with the device  30  for preventing excessive insertion described above. 
       FIGS. 13 and 14  show a device  70  for preventing excessive insertion according to a third embodiment of the present invention. The device  70  for preventing excessive insertion consists of a reference position establishment part  71 , a mobile part  72  and a linking part  73 . The reference position establishment part  71  consists of an annular body in the centre of the disc of which is formed a through-hole  74  through which the shaft  21  covered by the sheath  26  can pass with clearance. The mobile part  72  consists of a mobile part main body  75  and a fastening screw  76  which screws onto the upper end of the mobile part main body  75 . The mobile part main body  75  has a smaller diameter at its centre than the through-hole  74  of the reference position establishment part  71 , but it consists of an annular body formed with a through-hole  77  through which the shaft  21  covered by the sheath  26  can pass. 
     A screw (not depicted) is then formed on the outer periphery at the top of the mobile part main body  75 , and a plurality of flexible fastening pieces (not depicted) extending upwards are provided around the circumference at the upper-end edge of the mobile part main body  75 . Furthermore, the fastening screw  76  consists of an annular body in the centre of which is formed a through-hole  78  through which the shaft  21  covered by the sheath  26  can pass, and a screw with which the screw of the mobile part main body  75  screws together is formed on the inner peripheral surface. When the screw of the fastening screw  76  is screwed together with the screw of the mobile part main body  75 , the flexible fastening pieces of the mobile part main body  75  can be made to project to the inside of the mobile part main body  75  by turning the fastening screw  76  in the direction of fastening with respect to the mobile part main body  75 . By this means, the mobile part  72  can be fixed to the shaft  21  covered by the sheath  26 . 
     The linking part  73  is formed as a single piece with the reference position establishment part  71  and the mobile part main body  75  of the mobile part  72 , and it consists of a substantially cylindrical bellows-like body which can extend vertically. The device  70  for preventing excessive insertion is extendible between the state shown in  FIG. 13  in which the linking part  73  is extended to its maximum length, and the state shown in  FIG. 14  in which the linking part  73  is contracted to its minimum length. That is to say, with the device  70  for preventing excessive insertion, the difference between the maximum length and the minimum length of the linking part  73  constitutes the set length according to the present invention. The configuration of the components of the medical instrument provided with the device  70  for preventing excessive insertion other than the device  70  for preventing excessive insertion is the same as that of the components of the medical instrument provided with the device  30  for preventing excessive insertion other than the device  30  for preventing excessive insertion described above. 
     When the position of the gastrostomy catheter  10  is confirmed by means of the endoscope  20  using the device  70  for preventing excessive insertion configured in the manner described above, the endoscope  20  to which are attached the sheath  26 , bending instrument  40 , insertion aid  50  and device  70  for preventing excessive insertion is first of all positioned above the gastrostomy catheter  10 . The endoscope  20  and other components in this state are moved down, and the portion at the tip end is inserted into the insertion hole  14  of the gastrostomy catheter  10  and then insertion of the endoscope  20  etc. is stopped at the point where it has been ascertained on the image display part of the image display device that the tip end of the endoscope  20  has reached the cylindrical engagement part  18   a . The operation to attach the device  70  for preventing excessive insertion to the shaft  21 , with the sheath  26  interposed, is then carried out. 
     In a state in which the reference position establishment part  71  of the device  70  for preventing excessive insertion is in abutment with the upper surface of the reinforcing rib  57  of the insertion aid  50 , the mobile part  72  is pulled upwards to vertically extend the linking part  73 . In this state, the mobile part  72  is fixed to the shaft  21  to achieve the state shown in  FIG. 15  by turning the fastening screw  76  of the mobile part  72  in the direction of fastening with respect to the mobile part main body  75 . Next, the stomach S is expanded by sending air into the stomach S, after which the shaft  21  etc. is pushed further into the body. 
     By this means, as shown in  FIG. 16 , the portion at the lower part of the shaft  21  bends together with the sheath  26  so that the position of irradiation of the stomach wall SW by the light guides can be changed. Here too, the mobile part  72  gradually moves closer to the reference position establishment part  71 , and the position of irradiation of the stomach wall SW by the light guides moves upwards from below in accordance with this. At this time, the linking part  73  folds and contracts. Here too, the whole surface of the stomach wall SW can be irradiated by the light guides by turning the shaft  21  etc. in the axial direction. Then, when the linking part  73  has contracted to its minimum length, the shaft  21  etc. cannot be pushed any further inside the body. By this means, the shaft  21  etc. is prevented from being inserted more than necessary into the stomach S. 
     According to the device  70  for preventing excessive insertion, the whole of the device  70  for preventing excessive insertion contracts along the shaft  21 , and therefore the linking part  73  does not impede operation when the shaft  21  and other components are inserted into the gastrostomy catheter  10 . Furthermore, the mobile part  72  can be fixed more reliably to the shaft  21 . The other operational effects of the device  70  for preventing excessive insertion and the medical instrument provided with the device  70  for preventing excessive insertion are the same as the device  30  for preventing excessive insertion and the medical instrument provided with the device  30  for preventing excessive insertion described above. 
       FIG. 17  shows a device  80  for preventing excessive insertion according to a fourth embodiment of the present invention. The device  80  for preventing excessive insertion is used when the gastrostomy catheter  10  is fitted into a fistula formed in the patient&#39;s body using a fitting instrument  90  (see  FIG. 18 ), and it consists of a reference position establishment part  81 , mobile part  82  and linking part  83 . The reference position establishment part  81  consists of an elastic plate which is substantially C-shaped when viewed from above, and a through-hole  84  of which one side is open is formed in the centre thereof. The mobile part  82  consists of an elastic plate which is substantially C-shaped when viewed from above, and a through-hole  87  of which one side is open is formed in the centre thereof. The through-hole  84  of the reference position establishment part  81  is larger than the insertion hole  87  of the mobile part  82 . 
     The linking part  83  links the reference position establishment part  81  to the mobile part  82  due to the fact that it is formed as a single piece with the reference position establishment part  81  and the mobile part  82 , and it consists of a narrow, flexible linear part which runs vertically. Furthermore, the reference position establishment part  81  and the mobile part  82  are both flexible, and it is possible to widen the gap between both ends, and when the force to widen the gap is released, they return to their original shape due to the elasticity. In other words, the device  80  for preventing excessive insertion is configured in the same manner as the device  60  for preventing excessive insertion described above, but with a linking part that is shorter than the linking part  63 , and the reference position establishment part  81  can be attached in a state in which it can move in the longitudinal direction and the mobile part  82  can be fixed, with respect to a specific rod-like member. Consequently, the reference position establishment part  81  and the mobile part  82  can advance and retract with respect to each other within a range that is no greater than the length of the linking part  83 . In other words, with the device  80  for preventing excessive insertion, the length of the linking part  83  constitutes the set length according to the present invention. 
       FIG. 18  shows the fitting instrument  90  consisting of a push-rod  91  which acts as the rod-like member according to the present invention, and an engagement member  92  with which the push-rod  91  can engage. The push-rod  91  is provided with a main body part  93  comprising a rod body made of stainless steel, and a grip part  94  made of plastic. A pushing part  95  made of plastic is attached to the tip end of the main body part  93 . The pushing part  95  consists of a fixed part  95   a  which is fixed to the main body part  93  in a state in which the peripheral surface of the lower end of the main body part is covered, and a pushing piece  95   b  which extends down from the lower end of the fixed part  95   a.    
     The outer diameter of the fixed part  95   a  is set to be greater than the diameter of the through-hole  18  of the gastrostomy catheter  10 , and the diameter of the pushing piece  95   b  is set to be smaller than the diameter of the through-hole  18 . Accordingly, when the push-rod  91  is pushed downwards from the insertion hole  14  of the gastrostomy catheter  10 , the pushing piece  95   b  enters the through-hole  18 , and the fixed part  95   a  achieves a state in which its lower surface is in abutment with the upper surface of the cylindrical engagement part  18   a . Consequently, when the push-rod  91  is pushed further downwards into the gastrostomy catheter  10 , the stomach-internal fixed part  13  becomes elongate and extends. 
     Furthermore, a cylindrical part  96  which is configured as a single piece with the grip part  94  is formed to cover the peripheral surface of the main body part  93  at the lower portion of the grip part  94  at the top portion of the main body part  93 , and a plurality of engaging steps  96   a  are formed on the outer peripheral surface thereof The engaging steps  96   a  comprise annular protrusions which are semi-circular in cross section and are formed around the periphery of the cylindrical part  96 , and five of them are formed around the axial direction of the cylindrical part  96  at constant spacing. Furthermore, the upper surface of the grip part  94  is formed with an indented arcuate curved surface so that a hand or finger, especially the thumb, can be readily pressed against it when it is operated. 
     The engagement member  92  is endowed with the shape shown in  FIG. 18  by processing a sheet of stainless steel, and it is provided with a lower engagement part  97  and an upper engagement part  98 . The lower engagement part  97  and the upper engagement part  98  are linked by means of a linking piece  99  which is a rectangular plate that is longer in the vertical direction. The lower engagement part  97  consists of: a retaining piece  97   a  which is like a horizontal plate and is formed to be orthogonal with the linking piece  99 , extending horizontally towards the front of the drawing from the lower end of the linking piece  99 ; and a pair of hook parts  97   b  which are like vertical plates running orthogonal to the linking part  99  from both sides at the lower end portion of the linking part  99 , and are provided parallel to the retaining piece  97   a , constantly spaced from the retaining piece  97   a.    
     The shape of the retaining piece  97   a  when viewed from above is substantially U-shaped, with the tip ends being open, and the shape of the hook parts  97   b  when viewed from the side is substantially rectangular, being elongate in the horizontal direction and with the tip end being semi-circular. Furthermore, the inner portion of the substantial U-shape of the retaining piece  97   a  is formed as a recess of a size such that the boundary part between the external fixed part  11  and the tubular part  12  of the gastrostomy catheter  10  can enter it, and the gap between the retaining piece  97   a  and the hook parts  97   b  is set to be of a size such that the projecting pieces  11   b ,  11   c  are gripped from above and below. The upper engagement part  98  is formed to be orthogonal with the linking piece  99 , extending horizontally towards the front of the drawing from the upper end of the linking piece  99 , and it consists of a transversely-long horizontal plate-like body which extends to both sides of the linking piece  99 . 
     Furthermore, the length of the upper engagement part in the front to rear direction is set to be shorter, and an engaging recess  98   a  into which the portions between the engaging steps  96   a  of the push-rod  91  can be inserted is formed in the centre thereof at the front. Furthermore, a pair of protrusions  98   b , for engaging with the engaging steps  96   a  to prevent the release of the engagement between the push-rod  91  and the engaging member  92  when a portion between the engaging steps  96   a  of the push-rod  91  has entered the engaging recess  98   a , are provided on both sides of the engaging recess  98   a  at the front of the upper engagement part  98 . Furthermore, the portions on both the left and right of the upper engagement part  98  are curved downwards in order to facilitate the operation to grasp them with the hand, and the tip end of the retaining piece  97   a  is curved downwards in order to prevent the release of the engagement with the projecting pieces  11   b ,  11   c.    
     When the fitting instrument  90  and device  80  for preventing excessive insertion which are configured in this manner are used to make the gastrostomy catheter  10  positioned in the fistula formed in the patient&#39;s abdomen, the push-rod  91  is first of all inserted downwards into the tubular part  12  from the insertion hole  14  which is in an open state. The pushing piece  95   b  of the push-rod  91  is then pushed into the through-hole  18  of the stomach-internal fixed part  13 , and the fixed part  95   a  is brought into abutment with the upper surface of the cylindrical engagement part  18   a . Next, the projecting pieces  11   b ,  11   c  of the gastrostomy catheter  10  in this state are grasped by the retaining piece  97   a  and hook parts  97   b  of the engagement member  92 , along with which the engagement member  92  is attached to the gastrostomy catheter  10  and the push-rod  91 , in a state in which the main body part  93  is positioned inside the engaging recess  98   a.    
     An operation is then carried out to attach the device  80  for preventing excessive insertion to the push-rod  91 . The reference position establishment part  81  of the device  80  for preventing excessive insertion is attached to the main body part  93  by bringing the reference position establishment part  81  into abutment with the upper surface of the external fixed part  11  of the gastrostomy catheter  10 , so that the area between both ends of the reference position establishment part  81  is pushed by the main body part  93 . Next, the mobile part  82  is fixed to the main body part  93  by pushing the area between both ends of the mobile part  82  with the main body part  93 , in a state in which the linking part  83  is extended vertically in a straight line, and the state shown in  FIG. 19  is achieved. In this state, the push rod  91  is pushed further inside the gastrostomy catheter  10 . 
     With the upper surface of the grip part  94  being pushed using the hand, and the pushing piece  95   b  being prevented from separating from the through-hole  18 , the fingers are hooked under the upper engagement part  98  and the engagement member  92  is pulled upwards. By this means, the stomach-internal fixed part  13  is extended to make it elongate, and the mobile part  82  is gradually brought closer to the reference position establishment part  81 . At this time, the linking part  83  is bent so that it protrudes outwards. When the mobile part  82  is in abutment with the reference position establishment part  81 , the push-rod  91  cannot be pushed any further into the gastrostomy catheter  10 . This means that the stomach-internal fixed part  13  is prevented from extending more than necessary, and the stomach-internal fixed part  13  becomes appropriately narrow to pass through the fistula. 
     In this state, the edge of the engaging recess  98   a  of the engagement member  92  is engaged with a prescribed opposing engaging step  96   a  of the push-rod  91 . By means of this, as shown in  FIG. 20 , the tubular part  12  and the stomach-internal fixed part  13  reach a state in which they approximate a single rod. The stomach-internal fixed part which has extended in this way passes through the fistula formed in the abdominal wall AW and stomach wall SW of the patient together with the tip end portion of the push-rod  91 . Then, once the stomach-internal fixed part has entered the patient&#39;s stomach S, the fingers are hooked under the upper engagement part  98  to pull the engagement member  92  upwards, and the engaging recess  98   a  is released from the engaging step  96   a . By this means, as shown in  FIG. 21 , the shape of the stomach-external fixed part  13  reverts to its original substantially spherical, expanded state, and the push-rod  91  is moved upwards. Consequently, the mobile part  82  also moves upwards together with the push-rod  91 , and the linking part  83  reaches a state in which it extends straight. 
     As a result, the gastrostomy catheter  10  is maintained in a state in which it is prevented from being withdrawn from the fistula and is fitted in the patient&#39;s abdomen. In this state, the retaining piece  97   a  and the hook parts  97   b  are removed from the projecting pieces  11   b ,  11   c , and the engagement member  92  is removed from the gastrostomy catheter  10 , and also the push-rod  91  is withdrawn from the gastrostomy catheter  10 . The strip-shaped linking part  15   a  is then bent and the stopper part  16  is pushed into the insertion hole  14  to close off the insertion hole  14 . Furthermore, the operation described for the first embodiment is carried out when a patient is to be supplied with fluids such as nutrients and food in fluid form. 
     Then, when the gastrostomy catheter  10  becomes stretched or undergoes some other physical change after a certain period of use so that it has to be replaced, the operation described above is carried out to make the stomach-internal fixed part elongate, after which an operation is carried out to withdraw it from the fistula, but in this instance the device for preventing excessive insertion may or may not be used. With the device  80  for preventing excessive insertion according to this mode of embodiment, the stomach-internal fixed part  13  of the gastrostomy catheter  10  can be extended to make it appropriately narrow, and therefore the operation to make the gastrostomy catheter  10  positioned in the fistula is simple. 
     The present invention has been devised in order to deal with one or more of the problems described above, and it aims to provide a device for preventing excessive insertion rod-like member into a gastrostomy catheter, and a medical instrument is provided with the same. 
     In order to achieve the aim mentioned in the preceding paragraph, structural features of the device are designed based on the fact that it is used for preventing excessive insertion which is used when a rod-like member is inserted into a gastrostomy catheter. The catheter comprises in one embodiment a tubular part and a stomach-internal fixed part comprising an expanded body which links with the tip end of the tubular part and is provided with a through-hole at the tip end, the stomach-internal fixed part extending in an elongate fashion due to a portion on the through-hole side being pushed in the direction of the tip end side. The device comprises a reference position establishment part which can be installed at a prescribed portion on the base end opening side of the gastrostomy catheter in a state in which it can move in the longitudinal direction of the rod-like member; a mobile part which can be fixed to a prescribed portion of the rod-like member; and a linking part which can change the gap between the reference position establishment part and the mobile part within a range which is no greater than a set length, and further links the reference position establishment part and the mobile part. 
     The device for preventing excessive insertion according to one embodiment of the present invention comprises a reference position establishment part, a mobile part, and a linking part for linking the reference position establishment part and the mobile part. The linking part can change the gap between the reference position establishment part and the mobile part within a range which is no greater than a set length. The set length is the most suitable length or the maximum length when the rod-like member is inserted into the gastrostomy catheter. Then, when the rod-like member is inserted into the gastrostomy catheter, the tip end of the rod-like member is first inserted from the base end opening, and positioned at a prescribed position in the vicinity of the through-hole of the stomach-internal fixed part. In this state, the reference position establishment part is placed on the base end opening side, and also the operating part is fixed to the rod-like member in a state in which the length by which the mobile part can move is the set length. 
     Then, when the rod-like member is further inserted into the tip end side of the gastrostomy catheter, the reference position establishment part maintains a state in which it is placed at a portion on the base end opening side of the gastrostomy catheter. The rod-like member is inserted therein, and the mobile part moves to the reference position establishment part side together with the rod-like member. Consequently, when the gap between the reference position establishment part and the mobile part has become smaller and the movement distance of the mobile part has reached the set length, the mobile part can move no further, and therefore the rod-like member to which the mobile part is fixed cannot be inserted any further either. The insertion length of the rod-like member into the gastrostomy catheter accurately reaches the set length. Moreover, the reference position establishment part may be directly placed at the base end opening of the gastrostomy catheter, or it may be placed with another member interposed. 
     Furthermore, the reference position establishment part may be engaged with the base end opening of the gastrostomy catheter, or with another member attached to the base end opening, or it may simply be in a state of abutment with the base end opening of the gastrostomy catheter or the other member. In addition, a component provided with an external fixed part linked to the base end of the tubular part and formed with a tubular insertion hole passing through inside may be used as the gastrostomy catheter, and the reference position establishment part may be placed directly on the external fixed part, or it may be placed with another member interposed. If the reference position establishment part is placed directly on the external fixed part, it is simple to place the reference position establishment part on the gastrostomy catheter. 
     Furthermore, other structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the reference position establishment part as consisting of an annular body inside which the rod-like member can be inserted. Hence, the reference position establishment part can be attached to the rod-like member simply by inserting the rod-like member into the reference position establishment part, and therefore the operation to attach the reference position establishment part is simple. In such an embodiment, the reference position establishment part may be formed as a cylindrical shape, or it may be formed as an annular shape. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the reference position establishment part as consisting of an elastic member which is substantially C-shaped in transverse section, and the rod-like member can be inserted into the reference position establishment part in a state in which the gap between the end parts of the substantial C-shape of the elastic member is widened. Hence, the reference position establishment part can be attached to the rod-like member in a state in which the tip end of the rod-like member has been inserted up to the stomach-internal fixed part of the gastrostomy catheter, and therefore the operation when the rod-like member is inserted into the gastrostomy catheter is simple. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the mobile part as comprising an annular body provided with a fastening mechanism, and the mobile part can be fixed to a prescribed portion of the rod-like member by fastening the rod-like member using the fastening mechanism in a state in which the rod-like member is inserted into the mobile part. Hence, the mobile part can be easily attached to the rod-like member simply by inserting the rod-like member into the mobile part, and therefore the operation to attach the mobile part is simple. Furthermore, it is possible to use, as the fastening mechanism, a mechanism in which a cylindrical body, which is formed with a plurality of fastening pieces on the edge of the opening, and an annular body are screwed together. The fastening pieces are urged inwards by means of the screwing process, or by any mechanism with which it is possible to cause a screw to project inwards from the outer peripheral surface by screwing it into a screw hole passing from the outer peripheral surface to the inner peripheral surface of the annular body. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the mobile part as comprising an elastic member which can pinch the outer peripheral part of the rod-like member from both sides. The mobile part can be fixed to a prescribed portion of the rod-like member by first inserting the rod-like member into the mobile part in a state in which the mobile part is widened, and then fastening the rod-like member using the elasticity of the mobile part. 
     Hence, the mobile part can be attached to the rod-like member in a state in which the tip end of the rod-like member has been inserted up to the stomach-internal fixed part of the gastrostomy catheter, and therefore the operation when the rod-like member is inserted into the gastrostomy catheter is simple. Moreover, the mobile part may be a component in which the mobile part itself is formed from an elastic material, or it may be a component which can fix the rod-like member by pressing a certain piece against it with an elastic member such as a spring interposed. If the mobile part comprises an elastic material, it is possible to use a member having a substantially C-shaped transverse section, and the assembly can be designed so that the rod-like member can be inserted into the mobile part in a state in which the end parts of the substantial C-shape of the mobile part are widened, and the mobile part can be fixed to a prescribed portion of the rod-like member by fastening using the elasticity of the mobile part. Furthermore, if an elastic member such as a spring is used in the mobile part, a clip or other member like a clothes peg may be used. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the linking part as consisting of a rigid rail member, and the mobile part can slide on the linking part which comprises the rail member. Hence, the mobile part can be accurately moved by the set length. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention describe the linking part as consisting of a flexible linear part which links the respective prescribed portions of the reference position establishment part and of the mobile part. This means that the linking part can be simply configured. Furthermore, when the rod-like member is inserted into the gastrostomy catheter, the mobile part can be accurately moved by the set length even if the rod-like member rotates about the axis of the gastrostomy catheter. 
     Furthermore, additional structural features of the device for preventing excessive insertion according to an embodiment of the present invention lie in the fact that the linking part may comprise an extendible bellows-like part inside which the rod-like member can be inserted. Hence, the overall device for preventing excessive insertion is extendible along the rod-like member, and therefore the linking part does not impede operation when the rod-like member is inserted into the gastrostomy catheter. 
     Furthermore, structural features of the medical instrument according to an embodiment of the present invention describe that the medical instrument is provided with the device for preventing excessive insertion, where the medical instrument comprises an endoscope provided with a mechanism for bending the tip end portion when the rod-like member is inserted into the gastrostomy catheter and the tip end portion projects outward by a prescribed length from the through-hole of the stomach-internal fixed part. Hence, the tip end portion of the endoscope can be bent to a suitable angle inside the stomach, and therefore it is possible to reliably confirm the state of the gastrostomy catheter and the state of the stomach wall. The set length is set at the minimum length in the range whereby the whole surface of the stomach wall can be checked while the tip end portion of the endoscope is changed from a linear state to a bent state. In other words, the set length is set at a length such that any insertion beyond this is unnecessary. 
     Furthermore, other structural features of the medical instrument according to an embodiment of the present invention describe that the medical instrument is provided with the device for preventing excessive insertion, where the medical instrument comprises a push-rod which can push a portion on the through-hole side in the direction of the tip end side in a state in which the rod-like member is inserted into the gastrostomy catheter and the tip end is engaged with the peripheral edge of the through-hole of the stomach-internal fixed part. Hence, the stomach-internal fixed part of the catheter can extend to become suitably narrow, and therefore the operation to position the gastrostomy catheter in the fistula is simple. The set length is a suitable length so that the stomach-internal fixed part can extend to a suitable thickness. 
     Furthermore, the device for preventing excessive insertion according to the present invention is not limited to the modes of embodiment described above, and various modifications can be made within the technical scope of the present invention. For example, in the various embodiments described above, use is made of the gastrostomy catheter  10  provided with the external fixed part  11 , but in modes of embodiment 1 to 3, a gastrostomy catheter which is not provided with an external fixed part  11  may be used. The insertion aid  50  may also be omitted. In addition, the assemblies comprising the reference position establishment parts  31 ,  61 ,  71 ,  81 , mobile parts  32 ,  62 ,  72 ,  82 , and linking parts  33 ,  63 ,  73 ,  83  in the devices  30 ,  60 ,  70 ,  80  for preventing excessive insertion which were used in the exemplary embodiments described above can be changed, respectively. In addition, an assembly in which specific pieces are pushed into contact with the endoscope  20  or push-rod  91 , with an elastic member such as a spring interposed, may also be used. 
     Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. 
     When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawing[s] shall be interpreted as illustrative and not in a limiting sense.