Abstract:
An endoscope apparatus, comprising: an endoscope with a balloon attached to a tip end part of an insertion section, and an insertion assisting tool into which the insertion section of the endoscope is inserted and which assists the insertion section in being inserted into a body cavity, wherein a tip end part of the insertion assisting tool is constructed to have a diameter enlarging structure capable of being enlarged in diameter, and by enlarging a diameter of the tip end part, a balloon of the insertion section protruded from a tip end of the insertion assisting tool is made extractable from the insertion assisting tool.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an endoscope apparatus, and more particularly, to an endoscope apparatus having an endoscope with a balloon attached to a tip end of an insertion section, and an insertion assisting tool for guiding the insertion section of the endoscope into a body cavity.  
         [0003]     2. Description of the Related Art  
         [0004]     When the insertion section of an endoscope is inserted into a deep alimentary canal such as a small intestine, by only pushing the insertion section into the deep alimentary canal, the force is difficult to transmit to a tip end of the insertion section due to complicated bending of an intestinal canal, and insertion into a deep part is difficult. Thus, there is proposed an endoscope apparatus which prevents excessive bending and deflection of the insertion section by inserting the insertion section into a body cavity with an insertion assisting tool called an over tube or a sliding tube attached to the insertion section of the endoscope, and guiding the insertion section with this insertion assisting tool (for example, Japanese Patent Application Laid Open No. 10-248794).  
         [0005]     In conventional endoscope apparatuses, there is known a double balloon type endoscope apparatus provided with a balloon at a tip end part of an endoscope insertion section and provided with a balloon at a tip end part of an insertion assisting tool (for example, Japanese Patent Application Laid Open No. 2001-340462 and Japanese Patent Application Laid Open No. 2002-301019).  
         [0006]     Incidentally, as the procedure of the endoscope apparatus using an insertion assisting tool, a desired procedure is desired to be performed by inserting a treatment tool such as a balloon dilator for widening a narrow region of an intestinal canal and a contrast tube for injecting a contrast medium for observing the narrow region of the intestinal canal. However, these treatment tools are objects with comparatively large diameters, and therefore, they cannot be inserted by using a forceps channel inserted and disposed in the endoscope insertion section. Therefore, it has been desired to extract only the endoscope insertion section with the insertion assisting tool left in the body cavity and insert these treatment tools with the insertion assisting tool as a guide.  
       SUMMARY OF THE INVENTION  
       [0007]     However, the tip end part of the insertion assisting tool has a tip end formed into a throttled shape to prevent an intestinal wall from being entangled or pinched as disclosed in Japanese Patent Application Laid Open No. 2001-340462, and therefore, the balloon of the endoscope insertion section is caught by the tip end part of the insertion assisting tool when the endoscope insertion section is extracted, and it is difficult to extract the endoscope insertion section from the insertion assisting tool.  
         [0008]     The present invention is made in view of the above circumstances, and has its object to provide an endoscope apparatus in which an endoscope insertion section with a balloon attached to a tip end of the insertion section is capable of being extracted from an insertion assisting tool.  
         [0009]     In order to attain the above-described object, a first aspect of the present invention is in an endoscope apparatus comprising an endoscope with a balloon attached to a tip end part of an insertion section, and an insertion assisting tool into which the insertion section of the endoscope is inserted and which assists insertion section in being inserted into a body cavity, characterized in that a tip end part of the insertion assisting tool is constructed to have a diameter enlarging structure capable of being enlarged in diameter, and by enlarging a diameter of the tip end part, a balloon of the insertion section protruded from a tip end of the insertion assisting tool is made extractable from the insertion assisting tool.  
         [0010]     According to the first aspect of the present invention, the tip end part of the insertion assisting tool is constructed to have the diameter enlarging structure, and therefore, the insertion section having the balloon which is protruded from the tip end of the insertion assisting tool can be easily extracted from the insertion assisting tool.  
         [0011]     According to a second aspect of the present invention, the diameter enlarging structure is characterized by being made capable of being enlarged in diameter by constructing the tip end part of the insertion assisting tool by a soft member. Namely, a soft member such as rubber, sponge or the like is used for the material of only the throttled portion of the tip end part of the insertion assisting tool, whereby the tip end part is easily enlarged in diameter, and therefore, the insertion section having the balloon protruded from the tip end of the insertion assisting tool can be easily extracted from the insertion assisting tool.  
         [0012]     According to a third aspect of the present invention, in order to attain the aforementioned object, the diameter enlarging structure is characterized by being made capable of being enlarged in diameter by forming a notch in the tip end part of the insertion assisting tool. By enhancing flexibility by forming a notch in the throttled portion of the tip end part of the insertion assisting tool, the tip end part is easily enlarged in diameter, and therefore, the balloon can be easily extracted.  
         [0013]     A fourth aspect of the present invention is in an endoscope apparatus comprising an endoscope with a balloon attached to a tip end part of an insertion section by a catching member, and an insertion assisting tool into which the insertion section of the endoscope is inserted and which assists the insertion section in being inserted into a body cavity, characterized in that a surface of the catching member is formed into an inclined surface toward a downstream side from an upstream side in an extracting direction of the insertion section with respect to the insertion assisting tool, and thereby, the balloon of the insertion section protruded from the tip end of the insertion assisting tool is made extractable from the insertion assisting tool. The surface of the catching member is formed into the inclined surface of which height becomes larger toward the downstream side from the upstream side in the extracting direction, and the balloon is made extractable from the insertion assisting tool. Namely, when the insertion section is pulled in the extracting direction, the tip end of the insertion assisting tool rides on the inclined surface of the catching member and the balloon sinks inside the tip end part, and therefore, the insertion section can be easily extracted from the insertion assisting tool.  
         [0014]     In order to attain the aforesaid object, a fifth aspect of the present invention is in an endoscope apparatus comprising an endoscope with a balloon attached to a tip end part of an insertion section by a catching member, and an insertion assisting tool into which the insertion section of the endoscope is inserted and which assists the insertion section in being inserted into a body cavity, characterized in that the catching member and an outer peripheral surface of the insertion section are made substantially flush with each other by fitting the catching member in a recessed part formed in the outer peripheral surface of the insertion section, and thereby, the balloon of the insertion section protruded from the tip end of the insertion assisting tool is made extractable from the insertion assisting tool. When the insertion section is pulled in the extracting direction, the tip end part of the insertion assisting tool does not collide against the catching member which interferes with the extraction, and therefore, the insertion section can be easily extracted from the insertion assisting tool. By forming the recessed part in the outer peripheral surface of the insertion section to which the catching member is fitted, the outer diameter of the insertion section does not become thick after fitting of the catching member, and the recessed part also serves as the mark of the balloon attaching position.  
         [0015]     According to the present invention, the tip end part of the insertion assisting tool is constructed to have the diameter enlarging structure, and therefore, the balloon of the insertion section protruded from the tip end of the insertion assisting tool can be easily extracted from the insertion assisting tool. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a system schematic diagram of an endoscope apparatus according to an embodiment of the present invention;  
         [0017]      FIG. 2  is a perspective view showing a tip end part of an insertion section of an endoscope;  
         [0018]      FIG. 3  is a perspective view showing the tip end rigid part of the insertion section onto which a first balloon is fitted;  
         [0019]      FIG. 4  is a sectional side view showing a tip end part of an over tube through which the insertion section is inserted;  
         [0020]      FIG. 5  is an enlarged sectional view of an essential part showing a first embodiment in which a diameter enlarging structure is given to the over tube side;  
         [0021]      FIG. 6  is an explanatory view showing an insertion section extracting situation by the diameter enlarging structure shown in  FIG. 5 ;  
         [0022]      FIGS. 7A  to  7 H are explanatory views showing an operation method of the endoscope apparatus shown in  FIG. 1 ;  
         [0023]      FIGS. 8A  to  8 B are explanatory views showing a second embodiment in which the diameter enlarging structure is given to the over tube side;  
         [0024]      FIG. 9  is an enlarged sectional view of an essential part showing a third embodiment in which the diameter enlarging structure is given to the over tube side;  
         [0025]      FIG. 10  is an explanatory view showing an insertion section extracting situation by the diameter enlarging structure shown in  FIG. 9 ;  
         [0026]      FIG. 11  is an enlarged sectional view of an essential part showing the first embodiment in which the diameter enlarging structure is given to the insertion section side;  
         [0027]      FIG. 12  is an enlarged perspective view of a band shown in  FIG. 11 ;  
         [0028]      FIG. 13  is an explanatory view showing an insertion section extracting situation by the diameter enlarging structure shown in  FIG. 11 ; and  
         [0029]      FIG. 14  is an enlarged sectional view of an essential part showing the second embodiment in which the diameter enlarging structure is given to the insertion section side. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     Hereinafter, preferred embodiments of an endoscope apparatus according to the present invention will be explained in accordance with the attached drawings.  
         [0031]      FIG. 1  shows a system block diagram of an endoscope apparatus according to the embodiments of the present invention. The endoscope apparatus shown in the drawing is constructed by an endoscope  10 , an over tube (corresponding to an insertion assisting tool)  50 , and a balloon control device  100 .  
         [0032]     The endoscope  10  includes a hand operation section  14 , and an insertion section  12  connected to the hand operation section  14 . A universal cable  15  is connected to the hand operation section  14 , and a connecter (not shown) which is connected to a processor and a light source device not shown is provided at a tip end of the universal cable  15 .  
         [0033]     An air/water passing button  16 , a suction button  18 , and a shutter button  20  which are operated by an operator are provided in parallel on the hand operation section  14 , and a pair of angle knobs  22  and  22 , and the forceps insertion part  24  are provided respectively at predetermined positions. Further, the hand operation section  14  is provided with a balloon air port  26  for supplying air to a first balloon  30  and sucking air from the balloon  30 .  
         [0034]     The insertion section  12  is constructed by a flexible part  32 , a curving part  34  and a tip end rigid part  36 . The curving part  34  is constructed by connecting a plurality of node rings to be able to curve, and is remotely operated to curve by the rotational operation of a pair of angle knobs  22  and  22  provided on the hand operation section  14 . Thereby, a tip end surface  37  of the tip end part  36  can be faced in a desired direction.  
         [0035]     As shown in  FIG. 2 , the tip end surface  37  of the tip end part  36  is provided with an object optical system  38 , an illumination lens  40 , air/water passing nozzle  42 , a forceps port  44  and the like in predetermined positions. An air supply/suction port  28  is provided on an outer peripheral surface of the tip end part  36 , and this air supply/suction port  28  communicates with the balloon air port  26  in  FIG. 1  via an air supply tube (not shown) with an inner diameter of about 0.8 mm which is inserted into the insertion section  12 . Accordingly, air is blown out of the air supply/suction port  28  of the tip end part  36  by supplying air to the balloon air port  26 , and on the other hand, air is sucked from the air supply/suction port  28  by sucking air from the balloon air port  26 .  
         [0036]     As shown in  FIG. 1 , the first balloon  30  constituted of an elastic body such as rubber is detachably attached to the tip end part  36  of the insertion section  12 . The fist balloon  30  is formed by a bulging portion  30   c  in a center and attaching portions  30   a  and  30   b  at both ends of the bulging portion  30   c , and is attached to the tip end rigid part  36  side so that the air supply/suction port  28  is located inside the bulging portion  30   c , as shown in  FIG. 3 . The attaching portions  30   a  and  30   b  are formed to have smaller diameters than the diameter of the tip end part  36 , and after being closely fitted onto the tip end part  36  with their elastic forces, the attaching portions  30   a  and  30   b  are firmly fitted to an outer peripheral surface of the tip end part  36  by ring-shaped bands (catching members)  45  and  45  shown in  FIGS. 4 and 5 .  
         [0037]     The first balloon  30  fitted onto the tip end part  36  has its bulging portion  30   c  inflated in a substantially spherical shape by air supplied from the air supply/suction port  28  shown in  FIG. 2 . On the other hand, by sucking air from the air supply/suction port  28 , the bulging portion  30   c  is deflated and is closely fitted onto the outer peripheral surface of the tip end part  36 .  
         [0038]     The over tube  50  shown in  FIG. 1  is constructed by a tube body  51 , and a gripping part  52 . The tube body  51  is formed into a cylindrical shape as shown in  FIG. 4 , and has a slightly larger inner diameter than an outer diameter of the insertion section  12 . The tube body  51  is a molded product of flexible urethane resin, with its outer peripheral surface covered with lubricating coat and with its inner peripheral surface also covered with the lubricating coat. The rigid gripping part  52  is fitted in the tube body  51  in a watertight state, and the gripping part  52  is connected to the tube body  51  to be detachable and attachable. The insertion section  12  is inserted toward the tube body  51  from a base end opening  52 A of the gripping part  52 .  
         [0039]     A balloon air port  54  is provided at the base end side of the tube body  51  as shown in  FIG. 1 . An air supply tube  56  with an inner diameter of about 1 mm is connected to the balloon air port  54 , and this tube  56  is bonded to an outer peripheral surface of the tube body  51  and is provided to extend to a tip end portion of the tube body  51  as shown in  FIG. 4 .  
         [0040]     A tip end  58  of the tube body  51  is formed into a tapered shape to prevent the intestinal wall from being entangled or the like. A second balloon  60  constituted of an elastic body such as rubber is fitted onto the base end side of the tip end part  58  of the tube body  51 . The second balloon  60  is fitted in the state in which the tube body  51  penetrates through the balloon  60 , and is constructed by a bulging portion  60   c  in a center, and attaching portions  60   a  and  60   b  at both ends of the bulging portion  60   c . The attaching portion  60   a  at the tip end side is folded back to the inside of the bulging portion  60   c , and the attaching portion  60   a  folded back is fixed to the tube body  51  with an X-ray contrast thread  62  wound around the attaching portion  60   a . The attaching portion  60   b  at the base end side is disposed outside the second balloon  60 , and is fixed to the tube body  51  with a thread  64  wound around the attaching portion  60   b.    
         [0041]     The bulging portion  60   c  is formed into a substantially spherical shape in a natural state (the state in which the bulging portion  60   c  does not inflate or deflate), and as for the size, the bulging portion  60   c  is formed to be larger than the size of the first balloon  30  in a natural state (the state in which the balloon  30  does not inflate or deflate). Accordingly, when the air is supplied to the first balloon  30  and the second balloon  60  at the same pressure, the outer diameter of the bulging portion  60   c  of the second balloon  60  becomes larger than the outer diameter of the bulging portion  30   c  of the first balloon  30 . The outer diameter of the second balloon  60  is constructed so as to be φ50 mm when the outer diameter of the first balloon  30  is φ25 mm, for example.  
         [0042]     The aforementioned tube  56  is opened in the inside of the bulging portion  60   c , and an air supply/suction port  57  is formed. Accordingly, when air is supplied from the balloon air port  54 , the air is blown from the air supply/suction port  57  and thereby, the bulging portion  60   c  is inflated. When air is sucked from the balloon air port  54 , the air is sucked from the air supply/suction port  57 , and the second balloon  60  is deflated.  
         [0043]     Incidentally, the tip end part  58  of the tube body  51  is made of a sponge which is a soft member as shown in  FIG. 5 . This sponge tip end part  58  is formed into a tubular shape with a narrowed tip, but is elastically deformed easily by the pressing operation by the bands  45  and enlarged in diameter when the endoscope insertion section  12  is extracted from the tube body  51  as shown in  FIG. 6 .  
         [0044]     Meanwhile, the balloon control device  100  in  FIG. 1  is the device which supplies and sucks fluid such as air to and from the first balloon  30 , and supplies and sucks fluid such as air to and from the second balloon  60 . The balloon control device  100  is constructed by a device body  102  including a pump, sequencer and the like not shown, and a hand switch  104  for remote control.  
         [0045]     A front panel of the device body  102  is provided with a power supply switch SW 1 , a stop switch SW 2 , a pressure gauge  106  for the first balloon  30  and a pressure gauge  108  for the second balloon  60 . A tube  110  for supplying/sucking air to and from the first balloon  30 , and a tube  120  for supplying/sucking air to and from the second balloon  60  are attached to the front panel of the device body  102 . Liquid storing tanks  130  and  140  for storing body fluid, which flows backward from the first balloon  30  and the second balloon  60  when the first balloon  30  and the second balloon  60  are broken, are respectively provided at midpoints of the respective tubes  110  and  120 .  
         [0046]     Meanwhile, the hand switch  104  is provided with a similar stop switch SW 3  to the stop switch SW 2  at the side of the device body  102 , an ON/OFF switch SW 4  for supporting pressurization/decompression of the first balloon  30 , a pose switch SW 5  for keeping the pressure of the first balloon  30 , an ON/OFF switch SW 6  for supporting pressurization/decompression of the second balloon  60 , and a pose switch SW 7  for keeping the pressure of the second balloon  60 . This hand switch  104  is electrically connected to the device body  102  via a cable  150 .  
         [0047]     The balloon control device  100  which is constructed as above supplies air to the first balloon  30  and the second balloon  60  and inflates the first balloon  30  and the second balloon  60 , and controls the air pressure at a fixed value to keep the first balloon  30  and the second balloon  60  in the inflated state. The balloon control device  100  sucks air from the first balloon  30  and the second balloon  60  and deflates the first balloon  30  and the second balloon  60 , and controls the air pressure at a fixed value to keep the first balloon  30  and the second balloon  60  in the deflated state.  
         [0048]     Next, an operation method of the endoscope apparatus will be explained in accordance with  FIGS. 7A  to  7 H.  
         [0049]     First, as shown in  FIG. 7A , the insertion section  12  is inserted into an intestinal canal (for example, descending limb of duodenum)  70  in the state in which the over tube  50  covers the insertion section  12 . At this time, the first balloon  30  and the second balloon  60  are deflated.  
         [0050]     Next, as shown in  FIG. 7B , in the state in which the tip end  58  of the over tube  50  is inserted into a bent portion of the intestinal canal  70 , air is supplied to the second balloon  60  to inflate the second balloon  60 . As a result, the second balloon  60  is caught by the intestinal canal  70 , and the tip end  58  of the over tube  50  is fixed at the intestinal canal  70 .  
         [0051]     Next, as shown in  FIG. 7C , only the insertion section  12  of the endoscope  10  is inserted into a deep part of the intestinal canal  70 . Then, as shown in  FIG. 7D , air is supplied to the first balloon  30  to inflate the first balloon  30 . As a result, the first balloon  30  is fixed at the intestinal canal  70 . In this case, the first balloon  30  is smaller in size at the time of inflation than the second balloon  60 , and therefore, the burden exerted on the intestinal canal  70  is small, thus making it possible to prevent damage to the intestinal canal  70 .  
         [0052]     Next, after air is sucked from the second balloon  60  to deflate the second balloon  60 , the over tube  50  is pushed in, and inserted along the insertion section  12 , as shown in  FIG. 7E . Then, after the tip end  58  of the over tube  50  is pushed into the vicinity of the first balloon  30 , air is supplied to the second balloon  60  to inflate the second balloon  60  as shown in  FIG. 7F . As a result, the second balloon  60  is fixed at the intestinal canal  70 . Namely, the intestinal canal  70  is gripped by the second balloon  60 .  
         [0053]     Next, as shown in  FIG. 7G , the over tube  50  is drawn in. Thereby, the intestinal canal  70  contracts substantially straight, and excessive deflection and bending of the over tube  50  are eliminated. When the over tube  50  is drawn in, both the first balloon  30  and the second balloon  60  are caught by the intestinal canal  70 , but the friction resistance of the first balloon  30  is smaller than the friction resistance of the second balloon  60 . Therefore, even if the first balloon  30  and the second balloon  60  move to relatively separate from each other, the first balloon  30  with small friction resistance slides with respect to the intestinal canal  70 , and therefore, it does not happen that the intestinal canal  70  is damaged by being pulled by both the balloons  30  and  60 .  
         [0054]     Next, as shown in  FIG. 7H , air is sucked from the first balloon  30  to deflate the first balloon  30 . Then, the tip end part  36  of the insertion section  12  is inserted into as deep a part of the intestinal canal  70  as possible. Namely, the inserting operation as shown in  FIG. 7C  is performed again. Thereby, the tip end part  36  of the insertion section  12  can be inserted into a deep part of the intestinal canal  70 . When the insertion section  12  is further inserted into a deep part, the pushing operation as shown in  FIG. 7E  is performed after the fixing operation as shown in  FIG. 7D  is performed, the gripping operation as shown in  FIG. 7F  and the drawing operation as shown in  FIG. 7G , and the inserting operation as shown in  FIG. 7H  are repeatedly performed in sequence. Thus, the insertion section  12  can be further inserted into a deep part of the intestinal canal  70 .  
         [0055]     Next, when the over tube  50  is retained at a target region of the intestinal canal  70  and only the insertion section  12  is extracted from the over tube  50 , air is extracted from the first balloon  30  in the first place and thereby, the first balloon is deflated. Thereafter, when the over tube  50  is fixed and the insertion section  12  is extracted, the band  45  collides against the sponge tip end part  58  as shown in  FIG. 6 , and the sponge tip end part  58  is easily deformed by that force and enlarged in diameter. As a result, the band  45  and the first balloon  30  easily pass through the sponge tip end part  58 , and the insertion section  12  is easily extracted from the over tube  50 . In this manner, the insertion section  12  having the first balloon  30  protruded from the tip end of the over tube  50  can be easily extracted from the over tube  50  by giving the diameter enlarging structure in which the tip end part  58  is made of a sponge. The soft member such as rubber may be applied in place of the sponge.  
         [0056]      FIGS. 8A and 8B  show another embodiment in which the tip end part  58  of the over tube  50  is constructed to be in a diameter enlarging structure, and according to the drawings, notches  59 ,  59  . . . are provided in the tip end part  58  to facilitate elastic deformation of the tip end part  58  in the diameter enlarging direction. The notches  59  are formed at four locations equidistantly around the tip end part  58 , and are formed along an axial direction of the over tube  50 . Thus, when the band  45  shown in  FIG. 6  collides against the tip end part  58  in  FIG. 8 , the tip end part  58  receives the force in the extracting direction of the insertion section  12 , and is elastically deformed in the diameter enlarging direction shown by the arrow in  FIG. 8A  to allow passage of the band  45  and the first balloon  30 . As a result, the insertion section  12  can be easily extracted from the over tube  50 .  
         [0057]      FIG. 9  is another embodiment in which the tip end part  58  of the over tube  50  is constructed to have the diameter enlarging structure, and according to the drawing, the tip end part  58  is formed in a circular shape in section. Thereby, when the band  45  collides against the tip end part  58  and the force in the extracting direction acts on the tip end part  58  from the band  45 , the band  45  sinks into an inside of the tip end part  58  by being guided by the circular surface of the tip end part  58 , and the tip end part  58  is easily elastically deformed in the diameter enlarging direction shown by the arrow in  FIG. 10  by the force. As a result, the tip end part  58  allows the passage of the band  45  and the first balloon  30 . Thereby, the insertion section  12  can be easily extracted from the over tube  50 .  
         [0058]      FIG. 11  is an embodiment in which the band  45  for fitting the first balloon  30  onto the insertion section  12  is improved, and as shown in  FIGS. 11 and 12 , the surface of the band  45  is formed into an inclined plane  45 A of which height becomes larger from an upstream side in the extracting direction toward a downstream side, whereby it is made easy for the tip end part  58  of the over tube  50  to ride over the band  45  and the first balloon  30 . Namely, when the band  45  collides against the tip end part  58  and the force in the extracting direction acts on the tip end part  58  from the band  45  as shown in  FIG. 13 , the band  45  sinks into the inside of the tip end part  58  with the inclined surface  45 A as a guide, and the tip end part  58  elastically deforms in the diameter enlarging direction shown by the arrow in  FIG. 13  by the force. As a result, the tip end part  58  allows passage of the band  45  and the first balloon  30 . Thereby, the insertion section  12  can be easily extracted from the over tube  50 .  
         [0059]      FIG. 14  is an embodiment in which the insertion section  12  is improved, recessed parts  13  and  13  are formed at the band fitting positions of the outer peripheral surface of the insertion section  12 , and the band  45  is fitted in the recessed parts  13  and  13 , whereby the bands  45  and  45  and the outer peripheral surface of the insertion section  12  are made substantially flush with each other. Thereby, the band  45  passes through the tip end part  58  without colliding against the tip end part  58 , and therefore, the insertion section  12  can be easily extracted from the over tube  50 . By forming the recessed parts  13  in the insertion section  12 , the outer diameter of the insertion section  12  does not become large after the band  45  is fitted thereto, and the recessed parts  13  also serves as the marks of the balloon attaching position.  
         [0060]     In the embodiments, the over tube having the balloon  50  at the tip end is explained as the insertion assisting tool, but the insertion assisting tool is not limited to this, and the diameter enlarging structure of the embodiment may be applied to a sliding tube (insertion assisting tool without having a balloon) which is used for a colonoscope.