Ureteral stent

Abstract

This ureteral stent (1A) comprises a tubular body (2) extending between one end part (21) and the other end part (22). The tubular body (2) includes: a first curved part (31) configured to be disposed in the kidney; a second curved part (32) configured to be disposed in the bladder; and an extension part (30) extending between the first curved part (31) and the second curved part (32). At least a portion of a target curved part, which is at least one among the first curved part (31) and the second curved part (32), contains a first material, which is an X-ray opaque material, in a first proportion. The color of the at least a portion of the target curved part is a first color. The extension part (30) contains a second material, which is an X-ray opaque material, in a second proportion. The color of the extension part (30) is a second color. The X-ray transmittance of the target curved part is different from the X-ray transmittance of the extension part (30).

Description

ureteral stent

[0001] The present invention relates to a ureteral stent.

[0002] Ureteral stents are known for use in preventing blockage of the ureter, which connects the kidney and bladder. The ureteral stent described in Patent Document 1 has an intermediate section and hooks provided at both ends of the intermediate section. The intermediate section is placed in the ureter. The hook at one end of the intermediate section is placed in the kidney (renal pelvis), and the hook at the other end of the intermediate section is placed in the bladder. The placement of the ureteral stent in the body is performed using an endoscope to confirm that the hook at the other end of the intermediate section is placed in the appropriate position within the bladder.

[0003] Japanese Patent Application Publication No. 2-52646

[0004] There is a demand for a ureteral stent to be placed inside the body while its position can be confirmed under X-ray fluoroscopy. However, it is difficult to confirm the position of conventional ureteral stents under X-ray fluoroscopy. As a result, it is sometimes impossible to place the ureteral stent in the appropriate position inside the body under X-ray fluoroscopy.

[0005] An object of the present invention is to provide a ureteral stent that can be placed at an appropriate position in the body under X-ray fluoroscopy.

[0006] The ureteral stent of the present invention is a ureteral stent consisting of a tubular body extending between one end and the other end, wherein the tubular body includes a first curved portion configured to be placed in the kidney, a second curved portion configured to be placed in the bladder, and an extension portion extending between the first curved portion and the second curved portion, wherein at least a portion of a target curved portion, which is at least one of the first curved portion and the second curved portion, contains a first proportion of a first material that is an X-ray opaque material, and at least a portion of the target curved portion is a first color, the extension portion contains a second proportion of a second material that is an X-ray opaque material, and the extension portion is a second color, and the X-ray transmittance of the target curved portion is different from that of the extension portion.

[0007] A user who uses a ureteral stent to treat a patient can confirm the positions of the extension portion and the target curve portion of the ureteral stent within the body under X-ray fluoroscopy. Furthermore, because the X-ray transmittance of the target curve portion is different from that of the extension portion, the user can easily confirm the boundary position between the target curve portion and the extension portion under X-ray fluoroscopy. Therefore, the user can place the ureteral stent within the body under X-ray fluoroscopy with the target curve portion appropriately positioned in the kidney or bladder.

[0008] In the present invention, the first material and the second material may be different from each other. In this case, the difference in X-ray transmittance between the target bending portion and the extension portion of the ureteral stent can be achieved by making the first material different from the second material.

[0009] In the present invention, the first color and the second color may have different hues. Since the target curved portion and the extension portion have different hues, a user can easily confirm the boundary between the target curved portion and the extension portion when placing the ureteral stent using an endoscope. Therefore, when using an endoscope, a user can place the ureteral stent in the body with the target curved portion appropriately positioned in the kidney or bladder.

[0010] In the present invention, the second color may have a higher brightness than the first color. Since the brightness of the extension portion is higher than the brightness of the target curved portion, a user can easily confirm the extension portion even when hematuria is present in the urinary tract when placing the ureteral stent inside the body using an endoscope. Therefore, when using an endoscope, a user can place the ureteral stent inside the body with the extension portion properly positioned in the ureter.

[0011] In the present invention, the first ratio and the second ratio may be different from each other. In this case, the difference in X-ray transmittance between the target curved portion and the extension portion of the ureteral stent can be achieved by varying the ratio of the first material to the second material.

[0012] In the present invention, the first ratio may be greater than the second ratio, in which case the ureteral stent can improve the visibility of the target curved portion under X-ray fluoroscopy.

[0013] In the present invention, the first ratio may be greater than the second ratio by 20% by weight or more. In this case, the ureteral stent can improve the visibility of the target curved portion under X-ray fluoroscopy.

[0014] In the present invention, the first material may be tungsten. By using chemically stable tungsten as the first material, the safety of the ureteral stent can be improved.

[0015] In the present invention, the first ratio may be 50% by weight or more, in which case the visibility of the target curved portion under X-ray fluoroscopy can be improved.

[0016] In the present invention, the second material may be barium sulfate. By using chemically stable barium sulfate as the second material, the safety of the ureteral stent can be improved.

[0017] In the present invention, the second ratio may be 10% by weight or more and 30% by weight or less, in which case the visibility of the target curved portion under X-ray fluoroscopy can be improved.

[0018] In the present invention, the target bending portion may have a first portion that is curved in a circular shape and a second portion that is positioned inside an imaginary circle extending along the first portion and includes the end of the tubular body. By preventing the first portion and the second portion from overlapping, the possibility of metal artifacts occurring during CT scans using X-rays can be reduced. Furthermore, by preventing the end of the tubular body from protruding outward beyond the first portion, the end can be prevented from getting caught inside the body.

[0019] In the present invention, the target bending portion may be curved in a spiral shape, a third portion of the target bending portion adjacent to the extension portion and a fourth portion of the target bending portion including the end of the tubular body may overlap in the direction of extension of the spiral center, the first material may be contained in the portion of the target bending portion excluding the third portion, and the second material may be contained in the third portion. By preventing the portions of the target bending portion including the first material from overlapping with each other, the possibility of metal artifacts occurring during CT imaging using X-rays can be reduced.

[0020] In the present invention, the target bending portion may be curved in a spiral shape, a third portion of the target bending portion adjacent to the extension portion and a fourth portion of the target bending portion including the end portion of the tubular body may overlap in the direction of extension of the spiral center, and the X-ray transmittance of the third portion may be lower than the X-ray transmittance of the extension portion and the fourth portion. By preventing portions with low X-ray transmittance from overlapping with each other, it is possible to reduce the possibility of metal artifacts occurring during CT imaging using X-rays.

[0021] In the present invention, the X-ray transmittance of the adjacent portion of the target bending portion adjacent to the extension portion may be smaller than the X-ray transmittance of the extension portion, in which case the user can easily confirm the boundary position between the target bending portion and the extension portion under X-ray fluoroscopy.

[0022] FIG. 1 is a diagram showing a ureteral stent 1A. FIG. 2 is an enlarged view of a first curved portion 31. FIG. 3 is an enlarged view of a second curved portion 32. FIG. 4 is a diagram showing a state in which a ureteral stent 1A is placed in a body. FIG. 5 is a diagram showing a ureteral stent 1B. FIG. 6 is a table showing the compositions of samples 1 to 10. FIG. 7 is a table showing evaluation results under X-ray fluoroscopy. FIG. 8 is a table showing imaging results under X-ray fluoroscopy. FIG. 9 is a diagram showing a ureteral stent 1C. FIG. 10 is a diagram showing imaging results by CT examination using X-rays. FIG. 11 is a diagram showing a ureteral stent 1D. FIG. 11 is a diagram showing modified examples of ureteral stents 1A and 1C.

[0023] An embodiment of a ureteral stent 1 according to the present invention will be described with reference to the drawings. The drawings are used to explain the technical features that can be adopted by the present invention. The configuration of the device described is not intended to be limiting, but is merely an illustrative example.

[0024] The ureteral stent 1 is used, for example, after treatment for urolithiasis or urinary tract tumors, or for postoperative drainage of benign prostatic hyperplasia or urinary tract infections. The ureteral stent 1 is placed between the kidney and the bladder and is left in the body. The ureteral stent 1 plays a role in ensuring the passage of urine, facilitating the discharge of stone fragments from the body, reducing pain during stone discharge, and dilating the ureter before a procedure.

[0025] Conventionally, an endoscope is used as a method for placing a ureteral stent 1 in the body. Specifically, the method is as follows: First, an endoscope is inserted from the exit of the urethra, and the position of the ureteral opening (ureteral orifice) in the ureter, where it connects to the bladder, is confirmed. In this state, a guidewire is inserted into the ureter from the ureteral orifice. Next, the ureteral stent 1 is inserted along the guidewire, and the ureteral stent 1 is placed in the body between the kidney and the bladder. Note that a contrast medium may be used in combination to confirm whether one end of the ureteral stent 1 is placed in the kidney and the other end is placed in the bladder.

[0026] If the ureteral stent 1 is placed in a position that is biased toward the kidney, it must be removed under anesthesia. Furthermore, if the ureteral stent 1 is placed in a position that is biased toward the bladder, it may cause frequent urination or pain during urination. In contrast, the ureteral stent 1 can be placed in the body while its position is confirmed under X-ray fluoroscopy, instead of the conventional method using an endoscope. This allows a user who uses the ureteral stent 1 to treat a patient to place the ureteral stent 1 in the appropriate position within the body.

[0027] <Ureteral Stent 1A> With reference to Figures 1 to 3, a ureteral stent 1A, which is one embodiment of the ureteral stent 1, will be described. The ureteral stent 1A has a tubular body 2 with both ends curved. One end of the tubular body 2 is referred to as the "one end 21," and the other end is referred to as the "other end 22." The tubular body 2 has a cylindrical shape and extends between the one end 21 and the other end 22. The cross-sectional shape of the tubular body 2 is circular. The diameter of the tubular body 2 is, for example, 2 mm. The tubular body 2 has an inner lumen 23. The lumen 23 extends between the one end 21 and the other end 22. The cross-sectional shape of the lumen 23 is circular. The diameter of the lumen 23 is, for example, 1.3 mm. The direction extending along the center of the tubular body 2 is referred to as the "extension direction."

[0028] The material of the tubular body 2 is urethane. The tubular body 2 is provided with a plurality of side holes 28. Each side hole 28 penetrates into the inner cavity 23. The plurality of side holes 28 are arranged at equal intervals in the extension direction.

[0029] The tube body 2 includes an extension portion 30, a first curved portion 31, and a second curved portion 32. The first curved portion 31 is located near one end 21, and the second curved portion 32 is located near the other end 22. The extension portion 30 is interposed between the first curved portion 31 and the second curved portion 32. The extension portion 30 extends between the end of the first curved portion 31 opposite the one end 21 and the end of the second curved portion 32 opposite the other end 22. An imaginary straight line extending along the extension portion 30 is referred to as an "imaginary line C." The boundary between the extension portion 30 and the first curved portion 31 is referred to as an "boundary 11A." The boundary between the extension portion 30 and the second curved portion 32 is referred to as an "boundary 12A." The length in the extension direction between the boundaries 11A and 12A is denoted as L1. The length L1 is, for example, 300 mm.

[0030] The extension portion 30 is placed in the ureter with the ureteral stent 1A indwelling in the body. The extension portion 30 is provided with a plurality of markers 29. Each of the plurality of markers 29 includes one or more lines that circle the surface of the tubular body 2. The plurality of markers 29 are placed at positions where the distance from the boundary 11A is an integer multiple of a predetermined unit distance. The number of lines included in each of the plurality of markers 29 increases as the distance from the boundary 11A increases.

[0031] The first curved portion 31 is positioned in the kidney when the ureteral stent 1A is placed in the body. As shown in FIG. 2 , the first curved portion 31 includes a connecting portion 31A, a first portion 31B, and a second portion 31C. The connecting portion 31A extends linearly along an imaginary line C from the boundary 11A toward the opposite side from the extension portion 30. The first portion 31B is connected to the end of the connecting portion 31A opposite the boundary 11A. The second portion 31C is connected to the end of the first portion 31B opposite the connecting portion 31A. The first portion 31B and the second portion 31C are each curved in a circular shape. The first portion 31B extends in a circular shape along an imaginary circle 41 tangent to the imaginary line C passing through the connecting portion 31A. The position of the first curved portion 31 farthest from the extension portion 30 in the direction along the imaginary line C is referred to as the maximum position P11. A position of the first curved portion 31 opposite to the maximum position P11 across the center of the imaginary circle 41 is referred to as the maximum position P12. The second portion 31C extends circularly along an imaginary circle 42 that is tangent to the imaginary circle 41 at the maximum position P12 and is located inside the imaginary circle 41. The diameter of the imaginary circle 42 is smaller than the diameter of the imaginary circle 41. Since the imaginary circle 42 is located inside the imaginary circle 41, the second portion 31C is also located inside the imaginary circle 41. The one end 21 of the tube 2 is located inside the first portion 31B.

[0032] The extension portion 30, the connecting portion 31A, the first portion 31B, and the second portion 31C are arranged on a common imaginary plane. The direction perpendicular to this imaginary plane is defined as the orthogonal direction. In the orthogonal direction, the first portion 31B and the second portion 31C do not overlap.

[0033] The boundary between the connecting portion 31A and the first portion 31B is referred to as "boundary 11B." The boundary between the first portion 31B and the second portion 31C is referred to as "boundary 11C." The end of the second portion 31C opposite the boundary 11C is one end 21 of the tube body 2. The length of the first curved portion 31 is denoted as L11. The length L11 is, for example, 70 mm. The length between the boundary 11A and the maximum position P11 in the direction along the imaginary line C is denoted as L12. The length L12 is, for example, 17 mm. The radius of curvature of the first portion 31B corresponds to the radius of the imaginary circle 41 and is, for example, 8 mm. The radius of curvature of the second portion 31C corresponds to the radius of the imaginary circle 42 and is, for example, 5 mm.

[0034] The second curved portion 32 is disposed in the bladder while the ureteral stent 1A is placed in the body. As shown in FIG. 3 , the second curved portion 32 includes a connecting portion 32A, a first portion 32B, and a second portion 32C. The connecting portion 32A extends linearly along a virtual line C from the boundary 12A toward the opposite side from the extension portion 30. The first portion 32B connects to the end of the connecting portion 32A opposite the boundary 12A. The second portion 32C connects to the end of the first portion 32B opposite the connecting portion 32A. The first portion 32B and the second portion 32C are each curved in a circular shape. The first portion 32B extends in a circular shape along a virtual circle 43 tangent to the virtual line C passing through the connecting portion 32A. The position of the second curved portion 32 farthest from the extension portion 30 in the direction along the virtual line C is referred to as the maximum position P21. A position of the second curved portion 32 that faces the maximum position P21 across the center of the imaginary circle 43 is referred to as the maximum position P22. The second portion 32C extends circularly along an imaginary circle 44 that is tangent to the imaginary circle 43 at the maximum position P22 and is located inside the imaginary circle 43. The diameter of the imaginary circle 44 is smaller than the diameter of the imaginary circle 43. Since the imaginary circle 44 is located inside the imaginary circle 43, the second portion 32C is also located inside the imaginary circle 43. The other end 22 of the tube 2 is located inside the first portion 32B.

[0035] The extension portion 30, the connecting portion 32A, the first portion 32B, and the second portion 32C are arranged on a common imaginary plane. This imaginary plane coincides with the imaginary plane on which the extension portion 30, the connecting portion 31A, the first portion 31B, and the second portion 31C are arranged. The first portion 32B and the second portion 32C do not overlap in the orthogonal direction perpendicular to the imaginary plane.

[0036] The boundary between the connecting portion 32A and the first portion 32B is referred to as the "boundary 12B." The boundary between the first portion 32B and the second portion 32C is referred to as the "boundary 12C." The end of the second portion 32C opposite the boundary 12C is the other end 22 of the tube body 2. The length of the second curved portion 32 is denoted as L21. The length L21 is, for example, 50 mm. The length between the boundary 12A and the maximum position P21 in the direction along the imaginary line C is denoted as L22. The length L22 is, for example, 13 mm. The radius of curvature of the first portion 32B corresponds to the radius of the imaginary circle 43 and is, for example, 6 mm. The radius of curvature of the second portion 32C corresponds to the radius of the imaginary circle 44 and is, for example, 3 mm.

[0037] The radius of the imaginary circle 43 is smaller than the diameter of the imaginary circle 41 (see FIG. 2 ). The radius of the imaginary circle 44 is smaller than the diameter of the imaginary circle 42 (see FIG. 2 ). As shown in FIG. 1 , the first curved portion 31 and the second curved portion 32 are disposed on different sides of the imaginary line C.

[0038] <First Material, First Proportion, Second Material, Second Proportion> The extension portion 30, the first curved portion 31, and the second curved portion 32 each contain a radiopaque material. Radiopaqueness refers to the property of a component in a substance blocking a certain amount of X-ray transmission. When the extension portion 30, the first curved portion 31, and the second curved portion 32 contain a radiopaque material, a difference in density occurs between the extension portion 30, the first curved portion 31, and the second curved portion 32 when irradiated with X-rays and viewed through the material, making the extension portion 30, the first curved portion 31, and the second curved portion 32 visible. The radiopaque material contained in the first curved portion 31 and the second curved portion 32 is the same.

[0039] Hereinafter, the radiopaque material contained in the first bending portion 31 and the second bending portion 32 will be referred to as the "first material." The weight ratio of the first material to the urethane material of the tubular body 2 will be referred to as the "first proportion." The radiopaque material contained in the extension portion 30 will be referred to as the "second material." The weight ratio of the second material to the urethane material of the tubular body 2 will be referred to as the "second proportion." The first material, first proportion, second material, and second proportion can be changed as appropriate as long as the condition that the X-ray transmittance of the extension portion 30 is different from the X-ray transmittance of the first bending portion 31 and the second bending portion 32 is satisfied.

[0040] An example of a specific example of the first material, first ratio, second material, and second ratio is as follows: The first curved portion 31 and the second curved portion 32 contain tungsten (first material), an X-ray opaque material, at a ratio (first ratio) of 50% by weight. The extended portion 30 contains barium sulfate (second material), an X-ray opaque material, at a ratio (second ratio) of 10% by weight or more and 30% by weight or less. In this way, the first material and the second material are different, and the first ratio and the second ratio are also different. Furthermore, the first ratio is greater than the second ratio. More specifically, the first ratio is greater than the second ratio by 20% by weight or more. In this way, the X-ray transmittance of the first curved portion 31 and the second curved portion 32 is lower than the X-ray transmittance of the extended portion 30.

[0041] <First Color, Second Color> The first curved portion 31 and the second curved portion 32 have the same color. Hereinafter, the colors of the first curved portion 31 and the second curved portion 32 are referred to as the "first color," and the color of the extension portion 30 is referred to as the "second color." The first color and the second color can be changed as appropriate as long as the conditions that the hues of the first color and the second color have a higher brightness than the first color are satisfied.

[0042] An example of a specific example of the first color and the second color is as follows: For example, the first color is black and the second color is green. The hue of the first color is approximately 0°, and the hue of the second color is approximately 174°. The lightness of the first color is approximately 0%, and the lightness of the second color is approximately 79%. The saturation of the first color is approximately 0%, and the saturation of the second color is approximately 84%.

[0043] The first color of the first curved portion 31 and the second curved portion 32 and the second color of the extension portion 30 may be imparted by applying a pigment or the like to the surface of the tubular body 2. Alternatively, the first color of the first curved portion 31 and the second curved portion 32 and the second color of the extension portion 30 may be imparted by adding an X-ray opaque material (first material or second material) thereto.

[0044] <Usage of Ureteral Stent 1A> A user who uses the ureteral stent 1A to treat a patient inserts the ureteral stent 1A into the body from the exit of the urethra. The user adjusts the position of the ureteral stent 1A within the body while checking the positions of the first bending portion 31, the second bending portion 32, and the extension portion 30 under X-ray fluoroscopy. As shown in Figure 4, the user confirms that the first bending portion 31 is positioned near the exit of the kidney 91, more specifically, in the renal pelvis 92, and that the second bending portion 32 is positioned in the bladder 93, and then ends the operation.

[0045] <Functions and Effects of Ureteral Stent 1A> In ureteral stent 1A, the X-ray transmittance of the extension portion 30 is different from the X-ray transmittance of the first curved portion 31 and the second curved portion 32. Therefore, under X-ray fluoroscopy, the user can easily confirm the boundary 11A between the first curved portion 31 and the extension portion 30 and the boundary 12A between the second curved portion 32 and the extension portion 30 by the difference in density. Therefore, under X-ray fluoroscopy, the user can place ureteral stent 1 in the body with the first curved portion 31 properly positioned in the kidney 91 and the second curved portion 32 properly positioned in the bladder 93.

[0046] In the ureteral stent 1A, the first material that is the material of the first curved portion 31 and the second curved portion 32 is different from the second material that is the material of the extension portion 30. In this case, the difference in X-ray transmittance between the first curved portion 31, the second curved portion 32, and the extension portion 30 can be easily achieved by making the first material different from the second material.

[0047] In the ureteral stent 1A, a first ratio, which is the weight ratio of the material (first material) of the first curved portion 31 and the second curved portion 32, differs from a second ratio, which is the weight ratio of the material (second material) of the extension portion 30. In this case, the difference in X-ray transmittance between the first curved portion 31, the second curved portion 32, and the extension portion 30 can be easily achieved by varying the respective ratios of the first material and the second material. Furthermore, by making the first ratio 20% by weight or more greater than the second ratio, the difference in density between the first and second curved portions 31 and 32 under X-ray fluoroscopy can be increased, thereby improving the visibility of the boundary 11A between the first curved portion 31 and the extension portion 30 and the boundary 12A between the second curved portion 32 and the extension portion 30. Therefore, the user can easily confirm whether the first curved portion 31 is positioned in the kidney 91 and whether the second curved portion 32 is positioned in the bladder 93.

[0048] Tungsten is used as the material (first material) of the first bending portion 31 and the second bending portion 32. Tungsten has a high specific gravity and is highly effective at shielding X-rays. Tungsten is also known to have a high melting point and chemical stability. Therefore, by using tungsten as the first material, the safety of the ureteral stent 1A can be improved.

[0049] Barium sulfate is used as the material (second material) of the extension portion 30. Barium sulfate has a high absorption rate for X-rays. Barium sulfate is also known to be insoluble in water and harmless to the human body. Therefore, by using barium sulfate as the second material, the safety of the ureteral stent 1A can be improved.

[0050] Furthermore, by using tungsten as the first material and barium sulfate as the second material, the ureteral stent 1A can be easily visualized even when the intensity of the X-rays used for fluoroscopy is reduced, thereby reducing the amount of radiation exposure to patients and users.

[0051] One end 21 of the tubular body 2 is disposed inside the first portion 31B, and the other end 22 of the tubular body 2 is disposed inside the first portion 32B. Therefore, the ureteral stent 1A can prevent the one end 21 and the other end 22 from getting caught inside the body by preventing the one end 21 and the other end 22 from protruding outward from the first portions 31B and 32B.

[0052] A user may place a ureteral stent 1A in the body using an endoscope. In the ureteral stent 1A, the first color, which is the color of the first curved portion 31 and the second curved portion 32, and the second color, which is the color of the extension portion 30, have different hues. Therefore, when placing the ureteral stent 1A in the body using an endoscope, the user can easily confirm the boundary 11A between the first curved portion 31 and the extension portion 30 and the boundary 12A between the second curved portion 32 and the extension portion 30 based on the difference in the hues of the respective colors. Therefore, when using an endoscope, the user can place the ureteral stent 1 in the body with the first curved portion 31 appropriately positioned in the kidney 91 and the second curved portion 32 appropriately positioned in the bladder 93.

[0053] When a user places a ureteral stent 1A in the body using an endoscope, for example, if hematuria is present in the urinary tract, the visibility of the extension portion 30 placed in the ureter 94 may be reduced. In response to this, in the ureteral stent 1A, the second color of the extension portion 30 is brighter than the first color of the first curved portion 31 and the second curved portion 32. This allows the user to easily see the extension portion 30 even if hematuria is present in the urinary tract. Therefore, when using an endoscope, the user can place the ureteral stent 1A in the body with the extension portion 30 appropriately positioned in the ureter 94.

[0054] <Ureteral Stent 1B> Referring to Figure 5, a ureteral stent 1B, which is one embodiment of the ureteral stent 1, will be described. The tubular body 2 of the ureteral stent 1B has an extension portion 30, a first curved portion 81, and a second curved portion 82. The shape of the extension portion 30 is the same as that of the extension portion 30 of the ureteral stent 1A. The shapes of the first curved portion 81 and the second curved portion 82 are different from those of the first curved portion 31 and the second curved portion 32 of the ureteral stent 1A (see Figure 1). A boundary 11A is the boundary between the extension portion 30 and the first curved portion 81. A boundary 12A is the boundary between the extension portion 30 and the second curved portion 82.

[0055] The first curved portion 81 is placed in the kidney with the ureteral stent 1B indwelled in the body. The first curved portion 81 includes a connecting portion 81A and a spiral portion 81B. The connecting portion 81A extends linearly along the imaginary line C from the boundary 11A toward the opposite side to the extension portion 30. The spiral portion 81B connects to the end of the connecting portion 81A opposite the boundary 11A. The spiral portion 81B is curved spirally. The center of rotation of the spiral portion 81B is referred to as the "spiral center 86C." The spiral center 86C extends linearly. When viewed from one side in the extension direction of the spiral center 86C, the spiral portion 81B extends along an imaginary circle 86 centered on the spiral center 86C. Portions of the spiral portions 81B overlap in the extension direction of the spiral center 86C. The end of the spiral portion 81B opposite to the connecting portion 81A is one end portion 21. The spiral portion 81B has a protrusion 81C protruding toward the inside of the imaginary circle 86 near the one end portion 21.

[0056] The second curved portion 82 is disposed in the bladder while the ureteral stent 1B is indwelling in the body. The second curved portion 82 includes a connecting portion 82A and a spiral portion 82B. The connecting portion 82A extends linearly along the imaginary line C from the boundary 12A toward the opposite side from the extension portion 30. The spiral portion 82B connects to the end of the connecting portion 82A opposite the boundary 12A. The spiral portion 82B is curved spirally. The center of rotation of the spiral portion 82B is referred to as the "spiral center 87C." The spiral center 87C extends linearly. When viewed from one side in the extension direction of the spiral center 87C, the spiral portion 82B extends along an imaginary circle 87 centered on the spiral center 87C. Portions of the spiral portions 82B overlap in the extension direction of the spiral center 87C. The end of the spiral portion 82B opposite to the connecting portion 82A is the other end 22. The spiral portion 82B has a protrusion 82C protruding inward of the imaginary circle 87 near the other end 22.

[0057] The diameter of the imaginary circle 87 is smaller than the diameter of the imaginary circle 86. The first curved portion 81 and the second curved portion 82 are disposed on different sides of the imaginary line C.

[0058] The first curved portion 81 and the second curved portion 82 contain a first proportion of a first material that is radiopaque. The first curved portion 81 and the second curved portion 82 are a first color. The extension portion 30 contains a second proportion of a second material that is radiopaque. The extension portion 30 is a second color. An example of the first material is tungsten. An example of the first proportion is 50% by weight. An example of the first color is black. An example of the second material is barium sulfate. An example of the second proportion is 10% by weight or more and 30% by weight or less. An example of the second color is green.

[0059] <Functions and Effects of Ureteral Stent 1B> This ureteral stent 1B has the same effects as ureteral stent 1A. Furthermore, in ureteral stent 1B, one end 21 of tubular body 2 is positioned inside helical portion 81B, and the other end 22 of tubular body 2 is positioned inside helical portion 82B. Therefore, ureteral stent 1B prevents one end 21 and the other end 22 from protruding outside imaginary circles 86 and 87, thereby preventing one end 21 and the other end 22 from getting caught inside the body.

[0060] <Evaluation 1> The visibility of the ureteral stent 1B under X-ray fluoroscopy was evaluated. Samples 1 to 10 shown in Figure 6 were prepared. For comparison with Samples 1 to 10, a Goodman pusher catheter TG1126022 (Comparison 1), a Bard Inlay Optima 788622 (Comparison 2), and a Bard pusher catheter (attached to the Inlay Optima, Comparison 3) were also prepared. These samples were fixed to a phantom (material: acrylic resin, thickness: 20 cm), and the visibility under X-ray fluoroscopy was evaluated. The evaluation was performed both with and without a guidewire passing through the lumen 23 of the tubular body 2. The following three evaluation criteria were established, and each was evaluated on a three-level scale (Good, Average, Bad).

[0061] (1) Whether the first curved portion 81 and the second curved portion 82 can be clearly recognized. (2) Whether the extension portion 30 can be visually recognized. (3) Whether the difference in shape between the first curved portion 81 and the second curved portion 82 and the extension portion 30 can be distinguished when a guidewire is inserted into the lumen 23 of the tubular body 2. The evaluation results are shown in FIG. 7. FIG. 8 shows the results of photographing the sample without the guidewire inserted using an X-ray nondestructive inspection device (μRay 6800, manufactured by Matsusada Precision). Note that, since variations occurred in the dimensions of the first curved portion 81 and the second curved portion 82 during the manufacturing of Samples 1 to 10, the shapes shown by the photographic results in FIG. 8 also differ for each of Samples 1 to 10.

[0062] 7 and 8 , it was found that by using tungsten or barium sulfate as the material (first material) of the first bending portion 81 and the second bending portion 82 and by using barium sulfate as the material (second material) of the extension portion 30, the first bending portion 81, the second bending portion 82, and the extension portion 30 can be seen under X-ray fluoroscopy. Furthermore, it was found that by making the weight ratio (first ratio) of the radiopaque material contained in the first bending portion 81 and the second bending portion 82 20 wt % or more greater than the weight ratio (second ratio) of the radiopaque material contained in the extension portion 30, the boundaries 11A, 12A between the first bending portion 81 and the second bending portion 82 and the extension portion 30 can be seen well under X-ray fluoroscopy.

[0063] Furthermore, when tungsten is used as the first material contained in the first bending portion 81 and the second bending portion 82, it was found that the first bending portion 81 and the second bending portion 82 can be more clearly visible under X-ray fluoroscopy by setting the first proportion to 50 wt % or more. Furthermore, when barium sulfate is used as the first material contained in the first bending portion 81 and the second bending portion 82, it was found that the first bending portion 81 and the second bending portion 82 can be more clearly visible under X-ray fluoroscopy by setting the first proportion to 55 wt % or more. Furthermore, when barium sulfate is used as the second material contained in the extension portion 30, it was found that the extension portion 30 can be more clearly visible under X-ray fluoroscopy by setting the second proportion to at least 20 wt %. Furthermore, it was confirmed that results similar to those shown in Figures 7 and 8 can be obtained even when the second proportion is 10 wt % or more and 30 wt % or less. Therefore, when barium sulfate is used as the second material contained in the extension portion 30, it was found that the extension portion 30 can be clearly seen under X-ray fluoroscopy by setting the second ratio to be 10% by weight or more and 30% by weight or less.

[0064] <Ureteral Stent 1C> Referring to Figure 9, a ureteral stent 1C, which is one embodiment of the ureteral stent 1, will be described. The tubular body 2 of the ureteral stent 1C has an extension portion 30, a first curved portion 51, and a second curved portion 52. The shape of the extension portion 30 is the same as that of the extension portion 30 of the ureteral stents 1A (see Figure 1) and 1B (see Figure 5). The shapes of the first curved portion 51 and the second curved portion 52 differ from those of the first curved portion 31 and the second curved portion 32 of the ureteral stent 1A (see Figure 1) and match those of the first curved portion 81 and the second curved portion 82 of the ureteral stent 1B (see Figure 5). A boundary 11A is the boundary between the extension portion 30 and the first curved portion 51. A boundary 12A is the boundary between the extension portion 30 and the second curved portion 52.

[0065] The first curved portion 51 is placed in the kidney with the ureteral stent 1C indwelling in the body. The first curved portion 51 includes a connecting portion 51A and a spiral portion 51B. The connecting portion 51A extends linearly along the imaginary line C from the boundary 11A toward the opposite side to the extension portion 30. The spiral portion 51B is curved spirally. The center of rotation of the spiral portion 51B is referred to as the "spiral center 61C." The spiral center 61C extends linearly. When viewed from one side in the direction in which the spiral center 61C extends, the spiral portion 51B extends along an imaginary circle 61 centered on the spiral center 61C.

[0066] The spiral portion 51B includes a third portion 511 and a fourth portion 512. The third portion 511 is connected to an end of the connecting portion 51A opposite the boundary 11A. The fourth portion 512 is connected to an end of the third portion 511 opposite the connecting portion 51A. The third portion 511 and the fourth portion 512 have an overlapping portion 501 where they overlap in the direction in which the spiral center 61C extends.

[0067] The position of the first curved portion 51 that is farthest from the extension portion 30 in the direction along the imaginary line C is referred to as the maximum position P51. The position of the first curved portion 51 that faces the maximum position P51 across the helical center 61C is referred to as the maximum position P52. The boundary between the connecting portion 51A and the third portion 511 is referred to as the "boundary 15B." The boundary between the third portion 511 and the fourth portion 512 is referred to as the "boundary 15C." The boundary 15C is located closer to the maximum position P51 than the intermediate position between the maximum positions P51 and P52. The end of the fourth portion 512 opposite the boundary 15C is one end 21.

[0068] The second curved portion 52 is placed in the bladder with the ureteral stent 1C indwelling in the body. The second curved portion 52 includes a connecting portion 52A and a spiral portion 52B. The connecting portion 52A extends linearly along the imaginary line C from the boundary 12A toward the opposite side to the extension portion 30. The spiral portion 52B is curved in a spiral shape. The center of rotation of the spiral portion 52B is referred to as the "spiral center 62C." The spiral center 62C extends linearly. When viewed from one side in the direction in which the spiral center 62C extends, the spiral portion 52B extends along an imaginary circle 62 centered on the spiral center 62C.

[0069] The spiral portion 52B includes a third portion 521 and a fourth portion 522. The third portion 521 is connected to an end of the connecting portion 52A opposite the boundary 12A. The fourth portion 522 is connected to an end of the third portion 521 opposite the connecting portion 52A. The third portion 521 and the fourth portion 522 have an overlapping portion 502 that overlaps in the extension direction of the spiral center 62C.

[0070] The position of the second curved portion 52 that is farthest from the extension portion 30 in the direction along the imaginary line C is referred to as the maximum position P61. The position of the second curved portion 52 that faces the maximum position P61 across the helical center 62C is referred to as the maximum position P62. The boundary between the connecting portion 52A and the third portion 521 is referred to as the "boundary 16B." The boundary between the third portion 521 and the fourth portion 522 is referred to as the "boundary 16C." The boundary 16C is located closer to the maximum position P61 than the intermediate position between the maximum positions P61 and P62. The end of the fourth portion 522 opposite the boundary 16C is the other end 22.

[0071] The diameter of the imaginary circle 62 is smaller than the diameter of the imaginary circle 61. The first curved portion 51 and the second curved portion 52 are disposed on different sides of the imaginary line C.

[0072] The radiopaque material contained in the connecting portion 51A and the third portion 511 of the first bending portion 51, and the radiopaque material contained in the connecting portion 52A and the third portion 521 of the second bending portion 52, are both the same second material as the extension portion 30, for example, barium sulfate. On the other hand, the radiopaque material contained in the fourth portion 512 of the first bending portion 51, and the radiopaque material contained in the fourth portion 522 of the second bending portion 52 are both the first material, for example, tungsten. Therefore, the radiopaque material contained in the overlapping portions 501, 502 of the first bending portion 51 and the second bending portion 52, which overlap in the extension direction of the helical centers 61C, 62C, is different.

[0073] Furthermore, the colors of the respective portions differ depending on the radiopaque materials contained therein. Specifically, the colors are as follows: the connecting portion 51A and the third portion 511 of the first bending portion 51 are a second color (e.g., green), and the fourth portion 512 of the first bending portion 51 is a first color (e.g., black) that is different from the second color. Similarly, the connecting portion 52A and the third portion 521 of the second bending portion 52 are a second color (e.g., green), and the fourth portion 522 of the second bending portion 52 is a first color (e.g., black) that is different from the second color.

[0074] <Actions and Effects of Ureteral Stent 1C> The ureteral stent 1C inside the body may be imaged by a CT scan using X-rays. Furthermore, if the subject of the CT scan includes a portion with extremely low X-ray transmittance, metal artifacts may occur. Metal artifacts appear as scattered rays or noise around the portion of the captured image with extremely low X-ray transmittance. Therefore, to accurately analyze the captured image, it is preferable to suppress the occurrence of metal artifacts.

[0075] In contrast, when the first material is contained in the entire first curved portion 81 and the entire second curved portion 82, as in the case of ureteral stent 1B (see FIG. 5 ), the X-ray transmittance may be extremely low at the overlapping portions. This is because the X-ray transmittance of the portions containing the first material is set to be lower than that of the portions containing the second material. In other words, in ureteral stent 1B, portions containing the first material, which have low X-ray transmittance, overlap each other, making it more likely that metal artifacts will occur at the overlapping portions.

[0076] If the sole purpose is to suppress metal artifacts, it is possible to shorten the lengths of the first and second bending portions 81 and 82 or to shape them so that no overlapping portions are formed. However, in these cases, it becomes difficult to maintain the shapes of the first and second bending portions 81 and 82, which could result in, for example, the ureteral stent 1C being dislodged from the body. In contrast, with the ureteral stent 1C, the lengths of the first and second bending portions 81 and 82 are maintained and overlapping portions 501 and 502 are formed, thereby suppressing dislodgment from the body and suppressing metal artifacts.

[0077] In the ureteral stent 1C, the radiopaque material contained in the connecting portion 51A and the third portion 511 of the first bending portion 51, and the radiopaque material contained in the connecting portion 52A and the third portion 521 of the second bending portion 52 are both the second material. Therefore, the portions containing the first material do not overlap in the overlapping portions 501, 502. Therefore, when the ureteral stent 1C is imaged by a CT scan using X-ray selection, the occurrence of metal artifacts in the image can be suppressed.

[0078] <Evaluation 2> Evaluation was performed based on the results of CT scans using X-rays. As shown in ureteral stent 1C, samples 11 to 20 were prepared in which the materials of the extension section 30, connecting sections 51A and 52A, and third sections 511 and 521 were the second material, and the materials of the fourth sections 512 and 522 were the first material. These samples were used together with samples 1 to 10 (ureteral stent 1B) in <Evaluation 1>. The types and proportions of the first and second materials in samples 11 to 20 were the same as those in samples 1 to 10 (see Figure 6). Each of samples 1 to 20 was fixed to a phantom (Toughwater Phantom WD-4050, manufactured by Kyoto Scientific Co., Ltd.) and photographed by irradiating X-rays using a CT scanner. Evaluation was performed by comparing the photographed results. The evaluation results are shown in Figure 10. Note that, since variations occurred in the dimensions of the first curved portion 81 and the second curved portion 82 during the manufacturing of samples 1 to 20, the shapes shown by the evaluation results in FIG. 10 also differ for each of samples 1 to 20.

[0079] 10 shows that scattered rays associated with metal artifacts were suppressed in the imaging results (samples 11 to 20) when the second material was contained in the connecting portions 51A, 52A and the third portions 511, 521 compared to the imaging results (samples 1 to 10) when the first material was contained in all portions of the first bending portion 81 and the second bending portion 82. Therefore, it was found that by using a configuration in which the second material is contained in the connecting portion 51A and the third portion 511 of the first bending portion 51 and the connecting portion 52A and the third portion 521 of the second bending portion 52, and the first material is contained in the fourth portion 512 of the first bending portion 51 and the fourth portion 522 of the second bending portion 52, CT examination of the ureteral stent 1C can be performed with high accuracy.

[0080] <Ureteral Stent 1D> Referring to Figure 11, a ureteral stent 1D, which is one embodiment of the ureteral stent 1, will be described. The tubular body 2 of the ureteral stent 1D has an extension portion 30, a first curved portion 71, and a second curved portion 72. The shape of the first curved portion 71 is the same as the first curved portion 81 of the ureteral stent 1B (see Figure 5) and the first curved portion 51 of the ureteral stent 1C (see Figure 9). The shape of the second curved portion 72 is the same as the second curved portion 82 of the ureteral stent 1B (see Figure 5) and the second curved portion 52 of the ureteral stent 1C (see Figure 9). The extension portion 30 is the same as the extension portion 30 of the ureteral stents 1A (see Figure 1), 1B (see Figure 5), and 1C (see Figure 9).

[0081] The first curved portion 71 includes a connecting portion 71A and a helical portion 71B. The helical portion 71B includes a third portion 711 and a fourth portion 712. The connecting portion 71A, the helical portion 71B, the third portion 711, and the fourth portion 712 correspond to the connecting portion 51A, the helical portion 51B, the third portion 511, and the fourth portion 512 of the first curved portion 51 of the ureteral stent 1C (see FIG. 9 ), respectively. The second curved portion 72 includes a connecting portion 72A and a helical portion 72B. The helical portion 72B includes a third portion 721 and a fourth portion 722. The connecting portion 72A, the helical portion 72B, the third portion 721, and the fourth portion 722 correspond to the connecting portion 52A, the helical portion 52B, the third portion 521, and the fourth portion 522 of the second curved portion 52 of the ureteral stent 1C (see FIG. 9 ), respectively.

[0082] The radiopaque material and its weight ratio contained in the connecting portions 71A, 72A and the third portions 711, 721 are adjusted so that the X-ray transmittance of the connecting portions 71A, 72A and the third portions 711, 721 is smaller than the X-ray transmittance of the extending portion 30 and the fourth portions 712, 722. For example, the connecting portions 71A, 72A, the third portions 711, 721, and the fourth portions 712, 722 contain a first material (e.g., tungsten) as a radiopaque material, and the extending portion 30 contains a second material (e.g., barium sulfate) as a radiopaque material. Furthermore, the weight ratio of the first material contained in the connecting portions 71A, 72A and the third portions 711, 721 is set to a value greater than the weight ratio of the first material contained in the fourth portions 712, 722. As a result, the X-ray transmittance of the connecting portions 71A, 72A and the third portions 711, 721 is adjusted to be smaller than that of the extending portion 30 and the fourth portions 712, 722.

[0083] The hues of the color of the extension portion 30, the colors of the connecting portions 71A, 72A and the third portions 711, 721, and the colors of the fourth portions 712, 722 are all different from each other. The brightness of each color increases in the order of the brightness of the color of the connecting portions 71A, 72A and the third portions 711, 721, the brightness of the color of the fourth portions 712, 722, and the brightness of the color of the extension portion 30.

[0084] <Actions and Effects of Ureteral Stent 1D> Extremely low X-ray transmittance can be prevented at the connecting portion 71A of the first curved portion 71 and at the overlapping portion 701 where the third portion 711 and the fourth portion 712 overlap. Also, extremely low X-ray transmittance can be prevented at the connecting portion 72A of the second curved portion 72 and at the overlapping portion 702 where the third portion 721 and the fourth portion 722 overlap. In this way, by preventing portions with low X-ray transmittance from overlapping each other, ureteral stent 1D can reduce the occurrence of metal artifacts in images captured by CT scans.

[0085] The present invention is not limited to the above-described embodiment, and various modifications are possible. Unless otherwise specified, modifications will be described below using ureteral stent 1A as an example, but the modifications can also be applied to ureteral stents 1B, 1C, and 1D as appropriate.

[0086] The shapes of the first bending portion 31 and the second bending portion 32 are not limited to circular, and may be other shapes suitable for placement in the kidney 91 (renal pelvis 92) or the bladder 93. The specific examples of the first material, which is an X-ray opaque material contained in the first bending portion 31 and the second bending portion 32, and the first ratio, which is the ratio by weight of the first material, which is an X-ray opaque material contained in the extension portion 30, and the second ratio, which is the ratio by weight of the second material, which is an X-ray opaque material contained in the extension portion 30, are merely examples, and other materials and ratios may be used.

[0087] The first material contained in the first curved portion 31 and the second curved portion 32 and the second material contained in the extension portion 30 may be the same X-ray opaque material. A first ratio, which is the weight ratio of the first material contained in the first curved portion 31 and the second curved portion 32, may be smaller than a second ratio, which is the weight ratio of the second material contained in the extension portion 30. The first ratio and the second ratio may be the same. The hue and brightness of the first color, which is the color of the first curved portion 31 and the second curved portion 32, may be the same as the hue and brightness of the second color, which is the color of the extension portion 30. The brightness of the first color may be higher than the brightness of the second color. The X-ray transmittance of the first curved portion 31 and the second curved portion 32 may be higher than the X-ray transmittance of the extension portion 30.

[0088] The ureteral stent 1A may contain the first material at a first rate only in one of the first curved portion 31 and the second curved portion 32, and may not contain the first material in the other of the first curved portion 31 and the second curved portion 32. For example, the ureteral stent 1A may contain the first material at a first rate only in the first curved portion 31, whose position is difficult to confirm with an endoscope, and may not contain the first material in the second curved portion 32.

[0089] The radiopaque material contained in the first bending portion 31 may be different from the radiopaque material contained in the second bending portion 32. The X-ray transmittance of the first bending portion 31 may be different from the X-ray transmittance of the second bending portion 32, as long as the condition that the X-ray transmittance of each of the first bending portion 31 and the second bending portion 32 is different from the X-ray transmittance of the extension portion 30 is satisfied. For example, the X-ray transmittance of the extension portion 30 may be greater than the X-ray transmittance of the first bending portion 31, and the X-ray transmittance of the second bending portion 32 may be greater than the X-ray transmittance of the extension portion 30.

[0090] The first portion 31B of the first curved portion 31 is not limited to extending along the virtual circle 41, which is a perfect circle, and may extend, for example, along an elliptical virtual circle. The second portion 31C of the first curved portion 31 is not limited to extending along the virtual circle 42, which is a perfect circle, and may extend, for example, along an elliptical virtual circle. The same applies to the second portion 31C of the first curved portion 31 and the first portion 32B and second portion 32C of the second curved portion 32.

[0091] The second portion 31C of the first curved portion 31 may extend straight inward from the boundary 11C with the first portion 31B. The same applies to the second portion 32C of the second curved portion 32.

[0092] The second portion 31C of the first bending portion 31 and the second portion 32C of the second bending portion 32 may contain, instead of the first material, a second material that is the same as the radiopaque material contained in the extension portion 30. The first material may be contained only in the connecting portion 31A of the first bending portion 31 and the connecting portion 32A of the second bending portion 32. In this case, the first portion 31B and the second portion 31C of the first bending portion 31 and the first portion 32B and the second portion 32C of the second bending portion 32 may contain the same second material as the extension portion 30.

[0093] In the ureteral stent 1D, the connecting portions 71A, 72A and the third portions 711, 721 may contain a first material (e.g., tungsten), and the fourth portions 712, 722 and the extension portion 30 may contain a second material (e.g., barium sulfate). That is, the fourth portion 712 of the first curved portion 71 and the fourth portion 722 of the second curved portion 72 may contain the same second material as the radiopaque material contained in the extension portion 30.

[0094] The X-ray transmittance of the portions of the first curved portion 31 and the second curved portion 32 of the ureteral stent 1A adjacent to the extension portion 30 (hereinafter referred to as adjacent portions 311 to 313; see FIGS. 12(A) to 12(C)) may be lower than the X-ray transmittance of the extension portion 30. Similarly, the X-ray transmittance of the portions of the first curved portion 51 and the second curved portion 52 of the ureteral stent 1C adjacent to the extension portion 30 (hereinafter referred to as adjacent portions 513 to 515; see FIGS. 12(D) to 12(F)) may be lower than the X-ray transmittance of the extension portion 30.

[0095] For example, as shown in FIGS. 12A to 12C, a portion of the connecting portion 31A of the first curved portion 31, including the boundary 11A with the extending portion 30, corresponds to the adjacent portions 311 to 313. Here, the X-ray transmittance of the extending portion 30 is denoted as x(0). The X-ray transmittance of the adjacent portions 311 to 313 is denoted as x(1). The X-ray transmittance of the connecting portion 31A excluding the adjacent portions 311 to 313 is denoted as x(2). The X-ray transmittance of the first portion 31B of the first curved portion 31 is denoted as x(3). The X-ray transmittance of the second portion 31C of the first curved portion 31 is denoted as x(4). In FIGS. 12A to 12C, the X-ray transmittance x(1) of the adjacent portions 311 to 313 is smaller than the X-ray transmittance x(0) of the extending portion 30.

[0096] In Fig. 12(A), the values ​​of X-ray transmittances x(1), x(2), x(3), and x(4) satisfy the relationship: x(1)<x(2)=x(3)=x(4). In Fig. 12(B), the values ​​of X-ray transmittances x(1), x(2), x(3), and x(4) satisfy the relationships: x(1)<x(2)=x(3)>x(4) and x(1)>x(4). In Fig. 12(C), the values ​​of X-ray transmittances x(1), x(2), x(3), and x(4) satisfy the relationships: x(1)>x(2)=x(3)<x(4) and x(1)<x(4).

[0097] For example, as shown in Figures 12(D) to 12(F), a portion of the connecting portion 51A of the first curved portion 51 of the ureteral stent 1C, including the boundary 11A with the extension portion 30, corresponds to the adjacent portions 513 to 515. Here, the X-ray transmittance of the adjacent portions 513 to 515 is denoted as x(5). The X-ray transmittance of the connecting portion 51A excluding the adjacent portions 513 to 515 is denoted as x(6). The X-ray transmittance of the third portion 511 of the first curved portion 51 is denoted as x(7). The X-ray transmittance of the fourth portion 512 of the first curved portion 51 is denoted as x(8). In Figures 12(D) to 12(F), the X-ray transmittance x(5) of the adjacent portions 513 to 515 is smaller than the X-ray transmittance x(0) of the extension portion 30.

[0098] In Fig. 12(D), the values ​​of X-ray transmittances x(5), x(6), x(7), and x(8) satisfy the relationship: x(5)<x(6)=x(7)=x(8). In Fig. 12(E), the values ​​of X-ray transmittances x(5), x(6), x(7), and x(8) satisfy the relationships: x(5)<x(6)=x(7)>x(8), x(5)>x(8). In Fig. 12(F), the values ​​of X-ray transmittances x(5), x(6), x(7), and x(8) satisfy the relationships: x(5)>x(6)=x(7)<x(8), x(5)<x(8).

[0099] As described above, by making the X-ray transmittance of the adjacent portions 311 to 313 of the first curved portion 31 and the adjacent portions 513 to 515 of the first curved portion 51 smaller than the X-ray transmittance of the extension portion 30, the visibility of the boundary 11A under X-ray fluoroscopy can be improved.

[0100] 12, the magnitude relationship between the X-ray transmittances x(1) to x(4) and the magnitude relationship between the X-ray transmittances (5) to x(8) may be changed as appropriate as long as the condition that the X-ray transmittances x(1) and x(5) are smaller than the X-ray transmittance of the stretched portion 30 is satisfied. The X-ray transmittances x(1) to x(4) and the X-ray transmittances (5) to x(8) may be larger or smaller than the X-ray transmittance x(0) of the stretched portion 30.

Claims

1. A ureteral stent comprising a tubular body extending between one end and the other end, the tubular body including a first curved portion configured to be disposed in the kidney, a second curved portion configured to be disposed in the bladder, and an extension portion extending between the first curved portion and the second curved portion, wherein at least a part of a target curved portion, which is at least one of the first curved portion and the second curved portion, contains a first material that is an X-ray impermeable material at a first ratio, and at least a part of the target curved portion has a first color, the extension portion contains a second material that is an X-ray impermeable material at a second ratio, and the color of the extension portion is a second color, and the X-ray transmittance of the target curved portion is different from the X-ray transmittance of the extension portion.

2. The ureteral stent according to claim 1, wherein the first material is different from the second material.

3. The ureteral stent according to claim 1, wherein the hue of the first color is different from the hue of the second color.

4. The ureteral stent according to claim 1, wherein the second color has a higher lightness than the first color.

5. The ureteral stent according to claim 1, wherein the first ratio is different from the second ratio.

6. The ureteral stent according to claim 5, wherein the first ratio is greater than the second ratio.

7. The ureteral stent according to claim 6, wherein the first ratio is greater than the second ratio by 20% by weight or more.

8. The ureteral stent according to claim 1, wherein the first material is tungsten.

9. The ureteral stent according to claim 8, wherein the first ratio is 50% by weight or more.

10. The ureteral stent according to claim 1, wherein the second material is barium sulfate.

11. The ureteral stent according to claim 10, wherein the second ratio is 10% by weight or more and 30% by weight or less.

12. The ureteral stent according to claim 1, wherein the target curved portion has a first portion that curves circularly and a second portion that is disposed inside a virtual circle extending along the first portion and includes an end portion of the tubular body.

13. The target curved portion is curved in a spiral shape, and a third portion of the target curved portion that is close to the extending portion and a fourth portion of the target curved portion that includes the end portion of the tubular body overlap in the extending direction of the spiral center. The ureteral stent according to claim 1, wherein the first material is included in a portion of the target curved portion excluding the third portion, and the second material is included in the third portion.

14. The target curved portion is curved in a spiral shape, and a third portion of the target curved portion that is close to the extending portion and a fourth portion of the target curved portion that includes the end portion of the tubular body overlap in the extending direction of the spiral center. The ureteral stent according to claim 1, wherein the X-ray transmittance of the third portion is smaller than the X-ray transmittances of the extending portion and the fourth portion.

15. The ureteral stent according to claim 1, wherein the X-ray transmittance of an adjacent portion adjacent to the extending portion of the target curved portion is smaller than the X-ray transmittance of the extending portion.

Images