Position limiting assembly for a prostatic stent delivery system

Abstract

The utility model provides a limiting component for prostatic stent delivery system, including slender member, it can be along axial movement and be equipped with in the lumen of the pipe body of delivery system, axial movement of the slender member makes it switch between the limiting state and the unlocking state, when being in the limiting state, the distal end of the slender member extends the pipe body and locks the prostatic stent on the pipe body, when being in the unlocking state, the distal end of the slender member retracts to the pipe body, and the locking of the prostatic stent is cancelled.

Description

Technical Field

[0001] This utility model relates to the field of medical devices, specifically to a limiting component for a prostate stent delivery system. Background Technology

[0002] Benign prostatic hyperplasia (BPH), commonly known as enlarged prostate, is a common disease among middle-aged and elderly men. Approximately 50% of men over 60 years of age will experience varying degrees of BPH symptoms, and this figure approaches 90% among men in their 70s and 80s. Due to the enlarged prostate, the urethra is compressed, leading to symptoms such as difficulty urinating, frequent urination, incomplete urination, interrupted urination, and weak urination. As the condition worsens, it can also cause urethral stones, bladder prolapse, urinary tract infections, and even kidney damage.

[0003] Existing prostatic urethral stents with a retrieval structure include an inner sheath and an outer sheath. One end of the inner sheath has a snap-fit ​​structure with elastic barbs, with the section near the snap-fit ​​exposed to accommodate the stent. When the endoscope is inserted, it pushes open the barbs to hook the stent; when withdrawn, the barbs spring back to separate it. However, this method requires the sheath core and / or endoscope for proper positioning. When pushing open the sheath, the stent may be pushed out; when withdrawing, the snap-fit ​​may not return completely, leading to incomplete separation from the stent, interference, and displacement. Furthermore, when the endoscope is inserted after removing the sheath core, there is a risk of the stent falling out or shifting. Utility Model Content

[0004] This invention provides a limiting component for a prostate stent delivery system. This limiting component can lock and release the stent without relying on the forward and backward movement of the endoscope, completely avoiding the risk of stent interference or displacement caused by incomplete rebound. The limiting component includes an elongated member that is axially movable and inserted into the lumen of the delivery system's tubing. The axial movement of the elongated member allows it to switch between a limiting state and an unlocked state. When in the limiting state, the distal end of the elongated member extends out of the tubing and locks the prostate stent onto the tubing. When in the unlocked state, the distal end of the elongated member retracts into the tubing, releasing the locking of the prostate stent.

[0005] In some embodiments of this utility model, the elongated member includes:

[0006] In some embodiments of this utility model, the release tube defines an inner cavity suitable for the endoscope insertion portion to pass through;

[0007] A locking head with radial elastic deformation capability is disposed at the distal end of the release tube. When the limiting component is in the limiting state, the locking head extends out of the tube body and expands radially outward to lock with the distal end of the prostate stent. When the limiting component is in the unlocking state, the locking head retracts into the tube body and is constrained by the inner wall of the tube body to converge radially inward.

[0008] In some embodiments of this utility model, the proximal end of the release tube extends to the outer side of the proximal end of the tube body, and the extended section is provided with a sealing mechanism for the endoscope to pass through in a sealed manner.

[0009] In some embodiments of this utility model, the locking head includes at least one elastic arm, and the distal end of the elastic arm forms a limiting portion that cooperates with the distal end of the bracket for limiting.

[0010] In some embodiments of this utility model, the locking head includes two elastic arms with 2-4 spaced apart. The free end of the elastic arm is provided with a barb, and the corresponding inner tube has an axially extending clearance notch to form a guide groove that is adapted to the elastic arm.

[0011] According to some embodiments of the present invention, the internal thread of the locking part engages with the external thread of the proximal end of the sliding sleeve, and an elastic compression washer is provided between the locking part and the proximal end face of the sliding sleeve.

[0012] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the prostate stent delivery system provided in Example 1;

[0014] Figure 2 This is a cross-sectional view of the prostate stent delivery system provided in Example 1;

[0015] Figure 3 and Figure 4 for Figure 1 Enlarged views of parts I and II;

[0016] Figure 5 and Figure 6 A schematic diagram of the slender member provided in Example 1;

[0017] Figure 7 and Figure 8 This is a diagram showing the locking and unlocking states of the locking head;

[0018] Figure 9 This is a schematic diagram of the prostate stent delivery system with sheath core provided in Example 1;

[0019] Figure 10 This is a schematic diagram of the prostate stent delivery system provided in Example 2;

[0020] Figure 11 This is a cross-sectional view of the prostate stent delivery system provided in Example 2;

[0021] Figure 12 This is a cross-sectional view of the prostate stent delivery system provided in Example 2.

[0022] Figure label:

[0023] 1-Prostate stent, 2-Tube body, 100-First fluid channel, 200-Second fluid channel, 101-First fluid connector, 201-Second fluid connector, 3-Slender component, 4-Endoscope, 5-Sealing mechanism, 6-Outer tube, 7-Inner tube, 8-Release tube, 51-Adjusting knob, 52-Sealing washer, 31-Release tube, 32-Locking head, 321-Elastic arm, 322-Barb, 20-Guide groove, 9-Sheath core, 91-Protective cap, 10-Sliding tube, 11-Locking part, 12-Locking washer, 301-Third fluid connector, 21-Step. Detailed Implementation

[0024] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of this utility model, it should be understood that the terms "length", "upper", "lower", "near", "far", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0026] In the description of this utility model, "first feature" and "second feature" may include one or more of the features, "multiple" means two or more, "first feature above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them, and "first feature above", "above" and "over" the second feature may include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0027] Example 1

[0028] The prostate urethral stent system includes a temperature-responsive prostate stent 1 and a delivery system. The prostate stent 1 is designed as a tubular spring structure with radial support (such as a helical spring or mesh tube). The proximal and / or distal ends of the stent are designed with a flared, bell-shaped opening. This opening can radially contract at room temperature or low temperatures (e.g., below 30°C), so that its maximum outer diameter is approximately close to or equal to the outer diameter of the stent body, facilitating delivery through narrow urethra. When exposed to a target temperature (e.g., above 45°C), the opening can radially expand, returning to its preset anchoring shape, significantly larger than the outer diameter of the stent body (e.g., the expanded outer diameter can reach 1.5-3 times the outer diameter of the body), thereby firmly anchoring it to the target anatomical location within the urethra (e.g., the bladder neck or distal verumontanum). The prostate stent 1 can be made of a material with temperature-sensitive properties; for example, a nickel-titanium shape memory alloy with a nickel (Ni) content of approximately 55-56%, and a specific austenitic phase transformation end temperature (Af) set in the range of 30°C to 55°C. When the temperature of the support reaches or exceeds its Af point, the material undergoes a phase transition.

[0029] The procedure for inserting a prostate stent via the urethra using a delivery system is as follows: Local anesthetic is injected into the urethra and retained for 10 minutes to achieve anesthesia; the cystoscope is positioned close to the tip of the penis and marked on the cystoscope; the cystoscope is withdrawn to the proximal end of the external sphincter and distal end of the verumontanum, again marking the tip of the penis; the distance between the two marks is measured, and this measurement is repeated until two consecutive measurements with a difference of less than 10 mm are obtained. The average of the two measurements is the length of the prostate urethra; a 10 mm margin is added to the measured distance to compensate for shortening during stent expansion. If a perfectly matching size is not available, the longest size is used; the prostate stent system is opened, and the delivery system is rotated. Tighten the system's fastening nut and remove the protective liner forward; insert the rigid cystoscope until the lens protrudes 1-2 mm from the distal end of the delivery device; lift the delivery device assembly clip with the cystoscope, securing the prostate stent to the delivery device assembly; tighten the fastening nut at the tail end of the delivery device clockwise to secure the cystoscope to the delivery device assembly; connect one port of the delivery device to an infusion tubing for injecting room temperature irrigation fluid, and connect the other port to any infusion tubing for injecting hot sterile injection fluid; thoroughly lubricate the stent with gel, open the irrigation fluid, and complete the preparation work before stent implantation; insert the prostate stent connected to the cystoscope through the penile opening into the urethra and slowly advance the stent until it is 2-3 mm in front of the cystoscope. After pushing the stent to the designated position, keep it in a fixed position, stop injecting room temperature injection fluid, and inject 50 mL of 55-60℃ sterile injection fluid. The stent will expand due to heat as it moves away from the bladder segment. Loosen the fastening nut, keeping the delivery assembly stationary, and completely withdraw the cystoscope, then withdraw the delivery assembly. Reinsert the cystoscope into the urethra and advance it to the proximal end of the stent (closest to the urethral opening). Observe whether the stent has fully expanded and is in place. Do not pass through the stent here, as this may cause stent displacement. If the stent has fully expanded and is in place, the procedure is complete. If the stent has not fully expanded, a cystoscope with an operating channel can be used to align with the stent's flared end, and warm sterile injection solution can be re-injected to fully expand the stent and then the procedure is complete.

[0030] In related technologies, locking and releasing the stent is achieved by using the longitudinal displacement of the endoscope to push out the elastic clip. However, this method is prone to incomplete repositioning and incomplete separation from the stent.

[0031] Based on this, please refer to the following: Figure 1This application proposes a prostate stent delivery system, which includes a tube body 2, a first liquid channel 100, a second liquid channel 200, and a limiting component. The tube body 2 defines a lumen extending in an axial direction, and has a proximal end and a distal end, the distal portion of which is adapted to load a prostate stent 1. The first liquid channel 100 and the second liquid channel 200 are disposed on the tube body 2, respectively delivering a first-temperature liquid and a second-temperature liquid to the prostate stent 1. Specifically, the first liquid channel 100 is preferably used to deliver room-temperature saline (20-25°C), and its main function is to maintain lubrication and flushing during stent delivery. The second liquid channel 200 is used to deliver a high-temperature sterile injection solution (55-60°C), and its function is to trigger a phase change expansion of the temperature-sensitive material at the stent anchoring end. The limiting component includes an elongated member 3, which is axially movable and inserted into the lumen. The axial movement of the elongated member 3 allows it to switch between a limiting state and an unlocked state. When the elongated member 3 is in the limiting state, its distal end extends out of the tube body 2 and locks the prostate stent 1 onto the tube body 2. When the elongated member 3 is in the unlocked state, its distal end retracts into the tube body 2 to allow the prostate stent 1 to be released at the target position. This limiting component actively controls the limiting and locking of the prostate stent 1 through the axially movable elongated member 3. The locking and unlocking process is an active mechanical operation, independent of the passive rebound of the endoscope 4, completely avoiding the risk of stent interference or displacement caused by incomplete rebound. The delivery system provided by this utility model has its limiting component normally preset in the limiting state, supports a coreless design, is compatible with pre-installed endoscope 4, adopts an integrated design, significantly simplifies the preoperative preparation process, and basically eliminates the problem of stent dislodgement or displacement caused by accidental contact with the stent during the insertion of endoscope 4 before surgery, and avoids the risk of stent dislodgement caused by the step-by-step operation of endoscope 4 pushing out the inner core.

[0032] In some embodiments of this utility model, the elongated member 3 has a structural form including, but not limited to, tubular members and rod-shaped members, and the distal end of the elongated member 3 has a locking head to limit and unlock the prostate stent 1. In some embodiments, please refer to... Figure 5 and Figure 6 The tubular component is a hollow release tube 31, the inner cavity of which forms the endoscope 4 channel, and a locking head 32 is provided at its distal end. In some embodiments, the rod-shaped component and the independent endoscope 4 are inserted into the lumen of the tube body 2 side by side. In other embodiments, the rod-shaped component is inserted into the side wall channel of the tube body 2, and the endoscope 4 is inserted into the lumen of the tube body 2.

[0033] In this embodiment, the elongated member 3 includes a release tube 31 and a locking head 32 with radial elastic deformation capability. The release tube 31 defines an inner cavity suitable for the insertion portion of the endoscope 4 to pass through. The locking head 32 is disposed at the distal end of the release tube 31. When the limiting component is in the limiting state, the locking head 32 extends out of the tube body 2 and expands radially outward (see [reference]). Figure 7 The locking head 32 engages with the distal end of the prostate stent 1; when the limiting component is in the unlocked state, the locking head 32 retracts into the tube body 2 (see [reference]). Figure 8 The locking head 32 is radially constricted inward by the inner wall of the tube 2, completely separating from the support. In some examples, the locking head 32 is formed by axially cutting the distal end of the release tube 31 and then folding it outward, forming a petal-shaped or claw-shaped structure. The locking head 32 extends out of the tube 2 and relies on the elasticity of the material to expand radially, locking the distal end of the support; the locking head 32 retracts into the tube 2 and is forced to constrict by the pressure of the inner wall of the tube 2, completely separating from the support. In other examples, the locking head 32 is composed of multiple elastic arms welded or integrally formed from the distal end of the release tube 31, such as 2 to 4 circumferentially spaced elastic arms; the free end of the elastic arm is provided with a limiting part, such as a barb or a limiting protrusion. For details, please refer again. Figure 8 The locking head consists of two symmetrically distributed elastic arms 321. The free ends of the elastic arms are provided with barbs, and the corresponding distal side of the inner tube has an axially extending clearance notch to form a guide groove 20 adapted to the elastic arms. When the release tube 31 is pulled back to the unlocked state, the elastic arms 321 of the locking head 32 and their end barbs 322 slide proximally along the path of the guide groove 20. Initially, the barbs abut against the distal end of the prostate stent to lock it. When the prostate stent needs to be released, the release tube 31 is pulled back, and the elastic arms 321 move axially towards the proximal end of the inner tube until the barbs abut against the top wall of the guide groove. The proximal end wall (top wall) of the guide groove acts as a stop structure. When the elastic arm 321 retracts until its barbs 322 contact this end wall (e.g., Figure 8 As shown), the pull-back action is forcibly stopped. By limiting the final retraction position of the locking head, the stent release process is controllable, avoiding separation failures that may occur with traditional endoscopic push-open / rebound mechanisms.

[0034] In some preferred embodiments, please refer to Figure 5The release tube 31 extends proximally to the outer side of the tube body 2, and this extension is equipped with a sealing mechanism 5 for sealing the endoscope 4. Specifically, the sealing mechanism 5 includes an adjustment knob 51 and a sealing washer 52. When delivering the prostate stent 1, the endoscope 4 passes through the release tube 31, and the sealing washer 52 is deformed by tightening the adjustment knob 51, thus sealing the endoscope 4 channel. The sealing washer 52 can be made of an elastic material (such as medical silicone), and its inner diameter is slightly smaller than the outer diameter of the endoscope 4, which is achieved by adjusting the pressure of the adjustment knob 51. When delivering the prostate stent 1, the endoscope 4 passes through the release tube 31, and the adjustment knob 51 and locking washer 12 at the proximal end of the release tube 31 cooperate to seal the endoscope 4 channel. After confirming the anchoring position through the endoscope 4, the locking head 32 is retracted into the tube body 2 by pulling back the release tube 31, and the stent is finally released without the need for the endoscope 4 to assist in the release.

[0035] In this embodiment, please refer to Figure 2 , Figure 3 , Figure 4 The tube body 2 includes an inner tube 7 and an outer tube 6 coaxially sleeved together. The distal end of the outer tube 6 terminates near the distal end of the inner tube 7, exposing the distal section of the inner tube 7 to form a support section. The prostate stent 1 is fitted onto the outer surface of this support section. When the prostate stent 1 is fitted onto the support section, its outer diameter is consistent with the outer diameter of the outer tube 6, forming a smooth transition. The inner lumen of the inner tube 7 forms a first liquid channel 100 for delivering saline solution to flush the stent. The annular gap between the inner tube 7 and the outer tube 6 forms a second liquid channel 200 for delivering high-temperature liquid to expand the anchoring end of the stent. Specifically, the proximal end of the outer tube 6 is provided with a first liquid connector 101 communicating with the first liquid channel 100 and a second liquid connector 201 communicating with the second liquid channel 200. Optionally, the ports of the first liquid connector 101 and the second liquid connector 201 adopt the Luer connector standard. During operation, the endoscope pushes out the sheath core through the release tube, and the locking knob 51 and the sealing washer 52 work together to seal the endoscope channel. After confirming the anchoring position through the endoscope, the locking head 32 is retracted into the inner tube 7 by pulling the release tube, thereby releasing the stent without the need for endoscope intervention. This avoids the situation where the limit latch fails to return to its proper position, interfering with the stent and causing stent displacement.

[0036] Optionally, the maximum outer diameter φX of the locking head 32 in the expanded state satisfies: outer diameter of inner tube 7 + 0.5mm ≤ φX ≤ maximum outer diameter of prostate stent 1 in the compressed state. Please refer to [link / reference]. Figure 7 and Figure 8The locking head 32, in its expanded state, is larger than the outer diameter of the inner tube 7 to ensure sufficient mechanical interference with the distal end of the prostate stent. After expansion, the locking head 32 must not exceed the outer diameter of the prostate stent 1 in its compressed state to avoid excessive compression that could lead to stent plastic deformation and affect subsequent expansion. Furthermore, the protruding portion of the locking head 32 may rub against the urethral wall, increasing the risk of intraoperative trauma. This design ensures that the outer diameter of the delivery system is minimized, facilitating passage through narrow urethras. The stent is relatively fixed by extending the locking head 32 outwards. During release, the locking head 32 can retract into the inner tube 7, preventing interference with the stent due to incomplete retraction and potential stent displacement.

[0037] In this embodiment of the invention, based on the design of the limiting component structure, the delivery system adopts a sheath-less structure. The limiting component is in a normally controlled limiting state at the factory, directly and mechanically locking the distal end of the prostate stent 1. The insertion part of the endoscope 4 directly penetrates the inner cavity of the release tube 31 and is fixed by the proximal sealing mechanism 5. During delivery, the limiting component maintains the limiting state without the need for sheath obstruction. After reaching the target position, the release tube 31 is pulled back axially: the locking head 32 is radially constricted by the inner wall of the tube body 2; the stent automatically disengages, completing the release. Thus, the sheath removal step is omitted; manufacturing costs are reduced, and the risk of stent displacement caused by sheath removal is avoided.

[0038] Optionally, please refer to Figure 9 The delivery system retains compatibility with the configuration of the sheath core 9, which is slidably inserted into the lumen of the release tube 31. The distal end of the sheath core 9 is provided with a protective cap 91. When the sheath core 9 is in the initial position, the protective cap 91 abuts against the distal end of the locking head 32. In clinical use, the delivery system is opened, the endoscope is inserted to push out the sheath core, and then the prostate stent is released.

[0039] Example 2

[0040] This embodiment provides a prostate urethral stent system, which is basically the same as the prostate stent system provided in Embodiment 1. The only difference is that this embodiment only includes a tube body 2, that is, the design of inner and outer tubes in Embodiment 1 is abandoned. Thus, the tube body defines a liquid channel for conveying a first temperature liquid and a second temperature liquid, and a third liquid connector 301 is provided accordingly. At this time, the tube body 2 has a support section for supporting the prostate stent 1. The support section is provided with a step 21, and the proximal end of the stent abuts against the step 21 of the support section.

[0041] Example 3

[0042] Please see Figure 10 and Figure 11In this embodiment, based on embodiment 1 or 2, an indicator component is provided to indicate the placement position of the prostate stent 1. This indicator component prevents the stent from covering the verumontanum. After the verumontanum is observed by the endoscope, the stent is pushed forward by pressing the sliding tube to ensure that the stent does not cover the verumontanum.

[0043] The indicating component includes a slider and a locking mechanism. The slider is slidably sleeved on the outside of the tube body, and the slider is selectively fixedly connected to the tube body assembly via the locking part. In some embodiments, the slider includes a sliding tube 10, and the locking part includes a locking knob 11. The sliding tube is axially slidably disposed on the outer tube 6, and the locking knob is sleeved on the tube body assembly and threadedly engaged with the sliding sleeve. Specifically, an elastic compression washer 12 is provided between the locking knob 11 and the proximal end of the sliding tube 10. The locking knob 11 pre-locks the sliding tube 10 and the outer tube 6, fixing them as one unit. The endoscope 4 has been inserted into the inner tube 7, and the support is mounted on the distal end of the inner tube 7; L 滑动管 =L 外管 -L 前列腺支架 ±10mm. For example, when the length of prostate stent 1 is 40mm, the length of sliding tube 10 is designed to be the length of outer tube 6 minus 30-50mm.

[0044] It is understood that the indicator component provided in this embodiment can be used not only in the conveying system of Embodiment 1, but also in other conveying systems, such as the conveying systems provided in the prior art.

[0045] The system is inserted into the urethra. At this time, the locking knob 11 is locked, and the sliding tube 10 and the outer tube 6 move synchronously. After observing through the endoscope 4 that the distal end of the stent has reached the target position, the locking knob 11 is released, and the sliding tube 10 automatically retracts to the reference point on the body surface (such as the urethral opening). The outer tube 6 is pushed forward, and the sliding tube 10 remains stationary due to contact with the body surface until significant resistance is generated. At this point, the position of the sliding tube 10 is the proximal anchoring point of the stent, and the end position of the endoscope 4 is the distal end coverage point of the stent. The stent coverage range is verified. The measured length = sliding tube 10 position - end position of endoscope 4 = 40mm ± 2mm; if the measured value is within the range of 38-42mm, the positioning is considered successful. After the stent placement position and range are verified to be correct, the stent is anchored and released. Through the sliding tube 10 and the locking knob 11, the operation process of first observing, then anchoring, and then releasing the stent after it is inserted into the human body can be realized, effectively avoiding problems such as unsatisfactory stent release position or stent covering the verumontanum.

[0046] In some embodiments, the indicating component further includes axial scale marks on the surface of the outer tube 6 for assisting in length measurement and positioning confirmation.

[0047] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0048] In the description of this specification, the references to terms such as "embodiment," "specific embodiment," and "example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A limiting component for a prostate stent delivery system, characterized in that, It includes an elongated member that is axially movable and inserted into the lumen of the tube of the delivery system; the axial movement of the elongated member switches between a limited state and an unlocked state; when in the limited state, the distal end of the elongated member extends out of the tube and locks the prostate stent onto the tube; when in the unlocked state, the distal end of the elongated member retracts into the tube, releasing the locking of the prostate stent.

2. The limiting component according to claim 1, characterized in that, The elongated member includes: A release tube, wherein the release tube defines an internal cavity suitable for the insertion of an endoscope; A locking head with radial elastic deformation capability is disposed at the distal end of the release tube. When the limiting component is in the limiting state, the locking head extends out of the tube body and expands radially outward to lock with the distal end of the prostate stent. When the limiting component is in the unlocking state, the locking head retracts into the tube body and is constrained by the inner wall of the tube body to converge radially inward.

3. The limiting component according to claim 2, characterized in that, The proximal end of the release tube extends to the proximal outer side of the tube body, and the extended section is provided with a sealing mechanism for the endoscope to pass through in a sealed manner.

4. The limiting component according to claim 2, characterized in that, The locking head includes at least one elastic arm, the distal end of which forms a limiting portion that cooperates with the distal end of the bracket for limiting.

5. The limiting component according to claim 4, characterized in that, The locking head includes two elastic arms with 2-4 spaced intervals. The free end of the elastic arm is provided with a barb, and the corresponding inner tube has an axially extending clearance notch to form a guide groove that is adapted to the elastic arm.

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