JPH08187292A - Catheter - Google Patents

Abstract

PURPOSE: To provide a catheter capable of preventing a tip from dropping off, improving engagement and fixing of the tip with a sheath, and raising the inserting performance to a celom. CONSTITUTION: A tip 6 is engaged with the nose of a flexible sheath 7, an operation part is fixed to the at-hand side of the flexible sheath 7, the tip 6 and the operation part are connected by a flexible wire 8 for dropping prevention inserted through the flexible sheath 7, and a notch 6c for jointing the flexible wire 8 for dropping prevention is formed in the wall-thickness of the engaging part of the tip 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube for feeding a contrast agent or the like and a catheter for an injection needle or the like, which is used by being inserted into a treatment instrument insertion channel of an endoscope.

[0002]

2. Description of the Related Art A contrast tube which is one of catheters and which is inserted endoscopically into a body cavity to deliver a drug solution, a contrast agent, etc., has a flexible sheath with a bile duct or In order to improve the insertability into the pancreatic duct and to monitor the exact position in the body with a fluoroscope or the like, a tip chip made of a metal material which is a radiopaque material is attached.

Since this tip has a very small size, it is difficult to securely fix it to the flexible sheath with an adhesive or the like. Moreover, due to improper mounting or repeated use of the contrast tube, the joining force of the fitting portion between the flexible sheath and the distal tip may be weakened, and the distal tip may be separated from the flexible sheath. If it leaves the body cavity, its collection becomes very difficult. In order to eliminate such a problem, for example,
As described in Japanese Patent No. 48161, a fall-preventing member is fixed to the tip chip to prevent the tip tip from falling off.

As shown in FIG. 8, the fixing structure is such that a distal tip 6 is fitted to the distal end of a flexible sheath 7, and a fall prevention wire 8 is attached to the outer peripheral surface of the fitting portion of the distal tip 6. One end of the wire 8 is brazed by the braze 9, and the other end of the wire 8 is inserted into the hollow portion of the flexible sheath 7 and connected to the proximal side operation portion 3. Further, in order to strengthen the amount of fixing force with the flexible sheath, the fitting portion of the distal tip 6 has a spiral or
Annular irregularities perpendicular to the axis of the sheath 7 are provided. The cross-sectional shape of the unevenness is a saw blade shape as shown in FIG. 8, and in the illustrated example, the rear end is formed into a gentle slope in order to facilitate insertion of the tip 6 into the sheath 7.

[0005]

In the contrast tube constructed as described above, after the wire for preventing the cap is brazed on the surface of the cylindrical hollow distal end tip, the distal end tip is attached to the flexible sheath distal end. Since the wire is fitted and fixed in the opening, there is a problem that the outer diameter of the flexible sheath is increased only in the wire portion. When this contrast tube is inserted into the body cavity of a patient, it is considered to reduce the outer diameter dimension so as to minimize the pain to the patient, but as described above, it is given to the patient when the outer diameter becomes large. In addition to increasing pain, when inserting from the duodenal papilla into a thin lumen such as a bile duct, there is a problem that the insertion portion becomes difficult to insert and the operability deteriorates.

Therefore, in order to suppress the outer diameter of the sheath from being thickened, a distal end tip to which a wire is fixed is fitted and fixed to the sheath, and then the distal end portion of the sheath swollen with the wire is molded into a desired outer diameter by a molding die. Is being done.
When the outer diameter of the sheath is narrowed down by thermoforming using a molding die, the sheath thickness is reduced by the amount corresponding to the outer diameter of the wire, the strength is significantly reduced, and in the worst case, the sheath is broken. Occurs.

On the other hand, as shown in FIG. 8, in the case where the tip-shaped tip 6 is provided with a sawtooth-shaped concave-convex portion 6b on the surface of the fitting portion, the wire 8 is placed near the final slope of the concave-convex portion 6b. Since the row 9 is attached, a part of the row 9 may flow up the gentle slope into the concave portion of the uneven portion 6b. When the row 9 flows into the concave-convex portion 6b, the edge of the concave-convex portion 6b is rounded or the concave portion of the concave-convex portion 6b is filled with the row 9, so that the edge is hard to work and the tip 6 easily comes out of the sheath 7. There was an occasion. Therefore, the uneven portion 6b
It is necessary to perform a troublesome work such as scraping off the row 9 that has flown into the blade with a knife or the like.

The present invention has been made in view of these circumstances, and prevents the distal end tip from falling off, improves the fitting and fixing of the distal end tip and the flexible sheath, and inserts it into a body cavity. It is to provide a catheter capable of improving

[0009]

A catheter according to claim 1 of the present invention comprises a flexible sheath, a distal end tip having a fitting portion to be fitted to the distal end of the sheath, and a proximal side of the sheath. What is claimed is: 1. A catheter comprising a fixed operation section and a drop-prevention flexible wire which is inserted into the flexible sheath and connects the distal tip and the operation section, the catheter comprising: The fall prevention flexible wire is joined within the wall thickness.

A catheter according to claim 2 of the present invention comprises a flexible sheath, a distal end tip having a fitting portion fitted to the distal end of the sheath, and an operating portion fixed to the proximal side of the sheath. A saw blade having an edge in a distal direction at a fitting portion of the distal tip, the catheter comprising a detachable prevention flexible wire that is inserted into the flexible sheath and connects the distal tip and the operating portion. Form uneven parts,
In addition, a step is provided between the concave-convex portion and the wire attachment portion that cannot be exceeded by the bonding agent for bonding the wire.

[0011]

In the catheter according to the first aspect, since a wire for preventing falling is attached within the wall thickness of the tip,
The outer diameter of the flexible sheath can be suppressed from increasing. In the catheter according to claim 2, by providing a step between the uneven portion for preventing the slip-out prevention and the wire attachment portion, the adhesive or the molten brazing agent for joining the wire to the distal tip flows into the uneven portion due to the step. Is prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention, FIG. 1 (a) is a partial cross-sectional view showing the configuration of the distal end portion of a contrast tube as an example of a catheter, and FIG. -A
FIG. 2 is a cross-sectional view, FIG. 2 is a cross-sectional view showing a schematic configuration of an operating portion connected to the proximal side of the contrast tube, and FIG. 3 is a diagram for explaining a usage state of the contrast tube.

In FIGS. 1A, 1B and 2, 1
Is a contrast tube formed of a flexible material such as a Teflon tube for injecting a contrast agent and the like. The insertion portion 2 to be inserted into the treatment instrument insertion channel of the endoscope and the operator's hand side And an operation unit 3 for performing operations such as. The operation part 3 is a watertight cock 4 that keeps the watertight side always.
And a stylet 5 for preventing the treatment tool from buckling when the endoscope is inserted, and a water supply cock 12.
The operation unit 3 will be described later in detail with reference to FIG.

As shown in FIG. 1 (a), the insertion portion 2 has a flexible sheath 7, a hollow metal tip 6 fitted and fixed to the inside of the tip of the sheath 7, and a tip. It is composed of a wire 8 which prevents the falling off of 6. The outer diameter D1 of the distal end of the distal tip 6 is preferably smaller than the maximum outer diameter D2 of the insertion portion 2 in order to improve the insertability into the body cavity, and the inner diameter d of the distal tip 6 is such that a guide wire or the like can be inserted. It is large enough to secure the sex. The distal tip 6 has a constricted portion 6 for preventing the insertion portion 2 once inserted into the body cavity from coming off easily.
a is formed. A plurality of saw-tooth-shaped concave-convex portions 6b having edges are formed at the fitting portion of the tip 6 with the sheath 7. The uneven portion 6b has an edge formed toward the tip of the tip 6, and the edge bites into the sheath 7 to enhance the fixing force between the tip 6 and the sheath 7. One end of the wire 8 is brazed to the above-mentioned tip 6 by a braze 9. In this embodiment, the tip 8 is attached so that the wire 8 is bonded within the thickness of the tip 6.
A flat notch 6c is formed on the outer peripheral surface of the base end of the.

The wire 8 is accommodated between the sheath 7 and the notch 6c, and the notch 6c has a sufficient length to enhance the connection strength with the wire 8. The tip 6 is made of a metal that is opaque to X-rays, specifically, stainless steel,
Alternatively, it is made of a heavy metal such as tungsten or platinum, and has a smooth overall shape by shaving or metal injection molding, which is considered so as not to damage the living mucous membrane.

The wire 8 has one end fixed to the tip 6 and the other end fixed to the operating portion 3 by brazing, and connects the tip 6 and the operating portion 3 to each other. Wire 8
The tip tip 6 is not limited to brazing, and may be fixed by soldering, an adhesive, or the like, or welded. The wire 8
The tip of the is placed inside the sheath 7 so as not to contact the living body and damage the mucous membrane in the body.

The sheath 7 is made of a thermoplastic resin, specifically PT.
The tip 7 is made of a fluororesin having a small surface friction resistance such as FE and FEP, and after the tip 6 is press-fitted into the sheath 7, the sheath 7 is molded to a prescribed outer diameter using a molding die or the like. Furthermore, when inserting the insertion portion 2 into the duodenal papilla on the outer surface of the distal end of the sheath 7, black markings 10 having a width of 3 mm are provided at regular intervals so that the insertion length can be confirmed under endoscopic observation. It has been subjected. The black marking 10 is
Carbon black, which is harmless to the human body, is used as the pigment, and thermosetting resin is used as the curing material. Specifically, the thermosetting resin is produced from a phenol resin and a solvent, is applied to the sheath 7 at room temperature, and is cured and fixed at a temperature not exceeding the melting point of the sheath 7.

FIG. 2 is a cross-sectional view showing the schematic construction of the operating section connected to the proximal side of the contrast tube, and the vicinity of the operating section 3 will be described with reference to this figure. The sheath 7 and the wire 8 are connected to a pipe 11 that is adhesively fixed to the tip of a water feed cock 12 that constitutes the operation unit 3. Wire 8 is pipe 1
The rear end is folded back and fixed through the hollow part of No. 1. As a result, the wire 8 is strongly fixed between the pipe 11 and the water feeding cock 12, and when the catheter or the guide wire 23 is inserted into the contrast tube 1,
Depending on the edge of the wire 8, the catheter or the guide wire 23
It is possible to smoothly maintain the insertability of the hollow portion of the pipe 11 without damaging the.

The water feeding cock 12 has two lure lock ferrules 12a to which an injection cylinder (not shown) for feeding water and liquid can be attached. Lure lock clasp 1
A watertight cock 4 is attached to 2a to prevent a liquid from leaking from the operating section 3 when a catheter or a guide wire 23 described later is inserted during liquid delivery by an injection cylinder.

The watertight cock 4 is fixed to a housing 13 in the mouthpiece 13 having a luer taper fitted with a luer lock mouthpiece 12a at the rear of the operating portion 3 and is pressed by a housing until the inner diameter is completely closed. Deformable elastic tube 14 and elastic tube 14 screwed with the base 13
It is composed of a pressing base 15 capable of pressing. By rotating the pressing die 15 relative to the die 13, the pressing die 15 moves in the axial direction with respect to the die 13. The inner diameter of the elastic tube 14 can be changed by adjusting the pressing of the elastic tube 14 by the pressing die 15. The elastic tube 14 is made of silicone rubber, natural rubber or the like, and has a JIS hardness of 55 degrees or less,
Desirably, a relatively soft material of about 40 degrees is preferable. By using such a soft material, the elastic tube 14 can be easily deformed with a relatively light force to completely close the inner diameter, and the operating portion 3 is made watertight by rotating the pressing mouthpiece 15. be able to.

The luer lock mouthpiece 15a at the rear end of the pressing mouthpiece 15 has a knob 17 of the stylet 5 attached thereto.
The luer taper of is fitted. Stylet 5
Is composed of a knob 17 and a tube buckling prevention wire 16 fixed to the knob 17 by adhesion or welding. The watertight cock 4 and the stylet 5 are detachable so that they can be used properly for the purpose of improving the washability and sterilization or according to the purpose of use.

Next, a method of using the contrast tube of this embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining a usage state of the contrast tube. The contrast tube 1 is inserted into a treatment tool insertion channel (not shown) of the endoscope 18 which is inserted into the body cavity, particularly the duodenum 19, and the insertion portion 2 of the contrast tube 1 is projected from the distal end opening of the endoscope 18.
Next, the insertion device 2 of the contrast tube 1 is inserted into the bile duct 21 or the pancreatic duct 22 via the duodenal papilla 20 by operating the bending device of the endoscope 18 or the treatment device raising device. The insertion of the insertion part 2 of the contrast tube 1 into the bile duct 21 or the pancreatic duct 22 can be confirmed under fluoroscopy because the tip 6 is radiopaque. Further, an unillustrated injection cylinder is attached to the luer lock mouthpiece 12a above the water supply cock 12, and the contrast agent in this injection cylinder is sent to the bile duct 21 and the pancreatic duct 22 via the hollow inside of the sheath 7 and the hollow inside of the tip 6. To liquidate. After that, the shape of the bile duct 21 and the pancreatic duct 22 and the presence or absence of stones are confirmed under fluoroscopy.
The contrast tube 1 is removed from the treatment instrument insertion channel of the endoscope 18.

If the bile duct 21 or pancreatic duct 22 has a narrowing (not shown) and it is difficult to further advance the contrast tube 1, the guide wire 23 is used. The method of use is to first remove the stylet 5 from the contrast tube 1 and insert the guide wire 23 from behind the watertight cock 4. Further, the guide wire 23 is inserted into the hollow inside of the contrast tube 1 and is advanced until the bile duct 21 or the pancreatic duct 22 is narrowed. After confirming that the guide wire 23 has passed the stenosis, the contrast tube 1 is pushed along the guide wire 23 and pushed beyond the stenosis.

The guide wire 23 is attached to the contrast tube 1
When the bile duct 21 or the pancreatic duct 22 is imaged with the elastic tube 14 still inserted, the elastic tube 14 is tightened by pressing the elastic tube 13 and the elastic tube 14 is pressed.
The gap between the guide wire 23 and the guide wire 23 is eliminated, and the operating portion 3 is made watertight, and then the contrast medium is delivered by the injection cylinder. Furthermore, after completion of the imaging while inserting the guide wire 23, only the contrast tube 1 is removed from the treatment instrument insertion channel, and the guide wire 23 is placed in the body cavity.
The treatment of becomes easy. As an example, a guide wire 23 in which an EST knife or the like is placed to perform a duodenotomy.
By inserting the EST knife or the like into the bile duct 21 or the pancreatic duct 22 from the duodenum 19, the EST knife or the like can be easily inserted into the body cavity.

As described above, according to this embodiment, it is possible to suppress the outer diameter of the flexible sheath 7 from increasing and to improve the insertability of the contrast tube into the body lumen. Moreover, since the inner diameter of the distal tip 6 is secured as it is, the insertability of the guide wire 23 and the like in the catheter can be improved. Further, since the wire 8 fits into the flat notch portion 6c of the tip chip 6, the wire 8 can be positioned more than on the cylinder of the tip chip 6, which was difficult to be conventionally positioned.
Will be easier to position.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4 (a) is a diagram showing the configuration of the distal end portion of the contrast tube in the second embodiment of the present invention, and FIG. 4 (b) is a BB sectional view thereof. This embodiment is different from the first embodiment only in the shape of the cutout portion 6c and the tip shape of the wire 8, and the other configurations are completely the same as those in the first embodiment. Is omitted. As shown in FIGS. 4 (a) and 4 (b), in this embodiment, a part of the inner periphery of the cylindrical distal end tip 6 is notched so as to form a substantially rectangular parallelepiped groove in the longitudinal direction of the sheath 7. ing.
A wire 8 is brazed and fixed to the notch 6c by a braze 9. Furthermore, in order to ensure the insertability of the guide wire 23 and the like, the wire 8 protruding into the inner space of the tip 6 is scraped off by a drill or the like.

According to the present embodiment as described above, since the wire 8 does not project at all on the outer surface of the distal end tip 6, there is no concern that the outer diameter of the sheath 7 becomes large. Further, since the concavo-convex portion 6b can be provided over the entire region where the sheath 7 is press-fitted into the distal tip 6, the fixing force between the distal tip 6 and the sheath 7 can be increased. Other functions and effects are the same as those in the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A is a diagram showing the configuration of the distal end portion of the contrast tube in the third embodiment of the present invention, and FIG. 5B is its CC sectional view. This embodiment is different from the first embodiment only in the shape of the cutout portion 6c, and since the other construction is exactly the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. As shown in FIGS. 5 (a) and 5 (b), in this embodiment, a notch 6c penetrating from the inner periphery to the outer periphery of the tip 6 is formed. The width of the notch 6c is almost the same as the outer diameter of the wire 8. The wire 8 is inserted to a position where it does not reach the inner space of the tip 6 and is fixed to the notch 6c by brazing.

According to this embodiment, since the outer diameter of the wire 8 can be made substantially the same as the wall thickness of the tip 6, the tensile strength of the wire 8 can be increased and the wire can be prevented from falling off. Sex is more enhanced. Other functions and effects are the same as those in the first embodiment. On the other hand, in the above-described contrast tube 1 and the like, as shown in FIG. 8, in order to strengthen the fixing force of the distal tip 6 to the sheath 7, a saw-toothed concave-convex portion 6b is provided on the surface thereof. . Since the tip 6 is extremely small, the uneven portion 6b on the surface of the tip 6 and the wire 8 are arranged adjacent to each other, but the slope of the uneven portion 6b is gentle on the side where the wire 8 is located. , When the wire 8 is brazed to the tip 6,
Easily flow into the uneven portion 6b.

A contrast tube capable of solving these problems will be described below with reference to FIG. FIG. 6 is a diagram showing the configuration of the distal end portion of the contrast tube in the fourth embodiment of the present invention, and since the basic configuration is the same as that of the first embodiment described above, the same parts are designated by the same reference numerals and described. Is omitted. The difference from the first embodiment is that, as a step difference between the rear end of the uneven portion 6b (closest to the operation portion) and the wire attachment portion, a step for preventing the bonding agent such as the braze 9 from flowing out to the uneven portion 6b, The point is that a block 6d higher than the concave portion of the uneven portion 6b is provided. The angle formed by the block 6d and the tip 6 is substantially vertical. Further, it is preferable that the height of the apex of the block 6d is set high enough to prevent the row 9 from getting over, but in the present embodiment, the height of the apex of the uneven portion 6b is almost the same as that of the apex 6b so that the outer diameter of the sheath 7 does not become thick. It is set.

According to this embodiment, when a member such as the wire 8 is brazed or soldered to the tip chip 6, the block 6d prevents the solder 9 and solder from flowing into the concavo-convex portion 6b. The edge of the is not rounded by the row 9 and the troughs of the concave-convex portion 6b are not filled with the row 9, so that the distal tip 6 can be securely fitted and fixed in the sheath 7. Moreover, the troublesome work of scraping off the row 9 that has flowed into the uneven portion 6b with a knife or the like is not necessary, and the work efficiency is improved. Also, block 6
Since the wire 8 can be abutted against d, the positioning of the wire 8 becomes easy.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing the configuration of the distal end portion of the contrast tube in the fifth embodiment of the present invention. Since the basic structure is the same as that of the first embodiment described above, the same parts are designated by the same reference numerals and the description thereof will be omitted. The difference from the second embodiment is that a block 6d that forms an edge in the direction of the operating portion 3 is provided at the rear end of the uneven portion 6b on the surface of the fitting and fixing portion of the distal tip 6 with the sheath 7. It is a point. The height of the apex of the block 6d and the height of the apex of the uneven portion 6b are substantially the same.

According to this embodiment, even when a member such as the wire 8 is brazed or soldered to the tip chip 6 as in the fourth embodiment, the solder 9 and the solder flow into the concavo-convex portion 6b to form the concavo-convex portion. It is possible to prevent the row 9 from being covered on the edge of 6b and the concave portion of the uneven portion 6b to be filled with the row 9. In addition, since the edge of the concave-convex portion 6b often cuts into the sheath 7, the fixing force between the tip 6 and the sheath 7 increases.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made without departing from the scope of the invention. For example, although the cutouts 6c are flat in the first to fourth embodiments described above, the present invention does not necessarily require the cutouts 6c to be flat. Any shape may be used as long as it has an effect of suppressing the notch and the outer diameter thickening of the sheath 7. For example, the cross-sectional shape may be cut out in a triangular shape or a U-shape to form a groove shape that fits the wire 8. By thus forming the notch 6c in the groove shape, the positioning of the wire 8 is facilitated, and the brazing agent or the adhesive is less likely to flow out from the notch 6c to the outside, so that the sheath 7 and the tip 6 are separated from each other. The amount of fixing power can be increased.

Further, also in the blocks 6d in the fifth and sixth embodiments, the effect of preventing the row 9 from flowing into the uneven portion 6b can be obtained when the wire 8 and the tip 6 are brazed. Any angle and shape may be used as long as it is a material. However, it is desirable that the angle formed between the inclined surface of the block 6d on the wire 8 side and the tip 6 be 90 degrees or less. Further, one block 6d may be provided at the rear end of the uneven portion 6b (closest to the operation portion), but two or more blocks may be provided. Furthermore, the present invention is not limited to the above-described contrast tube, but can be applied to all endoscopic treatment tools such as injection needles and balloon catheters having a tip attached to the tip.

[Supplementary Note] Various configurations shown in the following paragraphs can be obtained by the embodiments described above. 1. The notch is characterized by notching the outer periphery of the hollow tip. 2. The notch is characterized by notching the inner circumference of the hollow tip. 3. The notch is characterized in that the hollow tip is made to penetrate from the inner circumference to the outer circumference.

4. The notch is characterized by being flat. 5. The notch has a groove. 6. The height of the block is the same as the height of the convex portion of the uneven portion. 7. The angle formed between the tip of the block and the wire side slope of the block is 90 degrees or less.

[0038]

As described above, according to the present invention, since a wire for preventing falling is attached within the wall thickness of the distal tip, it is possible to suppress the outer diameter of the flexible sheath from increasing, and the treatment is performed. The insertability of the tool into the body lumen can be improved. Further, by providing a step between the uneven portion for preventing the slip-out prevention and the wire attachment portion, it is possible to prevent the adhesive or the molten brazing agent for joining the wire to the tip from flowing into the uneven portion due to the step. .

[Brief description of drawings]

1A is a partial cross-sectional view showing a configuration of a distal end portion of a contrast tube in a first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line AA in FIG. 1A.

FIG. 2 is a cross-sectional view showing a schematic configuration of an operation unit connected to the proximal side of a contrast tube.

FIG. 3 is a diagram for explaining a method of using a contrast tube.

4A is a diagram showing a configuration of a distal end portion of a contrast tube according to a second embodiment of the present invention, and FIG. 4B is the same as FIG. 4A.
BB sectional drawing in.

5A is a diagram showing a configuration of a distal end portion of a contrast tube in a third embodiment of the present invention, and FIG. 5B is a sectional view taken along line CC of FIG. 5A.

FIG. 6 is a diagram showing a configuration of a distal end portion of a contrast tube according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a distal end portion of a contrast tube according to a fifth embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a distal end portion of a contrast tube in a conventional example.

[Explanation of symbols]

 1 Contrast tube 2 Insertion part 3 Operation part 4 Watertight cock 5 Stylet 6 Tip tip 6a Constriction part 6b Concavo-convex part 6c Cutout part 6d Block 7 Sheath 8 Wire 9 Low 10 Marking 11 Pipe 12 Water feeding cock 12a Luer lock base 13 Elastic 14 Tube 15 Pressing mouthpiece 15a Luer lock mouthpiece 16 Tube buckling prevention wire 17 Stylet knob 18 Endoscope 19 Duodenum 20 Duodenal papilla 21 Bile duct 22 Pancreatic duct 23 Guide wire

Claims (2)

[Claims] 1. A flexible sheath, a distal end tip having a fitting portion to be fitted to the distal end of the sheath, an operating portion fixed to the proximal side of the sheath, and a flexible sheath inside the flexible sheath. In a catheter that is inserted and connects the distal tip and the operation portion with a drop-preventing flexible wire, the drop-preventing flexible wire is joined within the thickness of the fitting portion of the tip tip. A catheter characterized by the following. 2. A flexible sheath, a distal end tip having a fitting portion to be fitted to the distal end of the sheath, an operating portion fixed to the proximal side of the sheath, and a flexible sheath inside the flexible sheath. In a catheter comprising a fall-preventing flexible wire that is inserted and connects the distal end tip and the operating portion, a saw-toothed concavo-convex portion having an edge in the distal direction is formed in the fitting portion of the distal end tip, A catheter characterized in that a step is provided between the uneven portion and the wire attachment portion so that a bonding agent for joining the wire cannot pass through.