Hydraulic control system for child sheath-free flexible ureteroscope

Abstract

The invention relates to the technical field of medical instruments, and provides a hydraulic control system for a child sheath-free flexible ureteroscope, the system comprises a flexible ureteroscope body and an in-vitro hydraulic control unit, the in-vitro hydraulic control unit comprises a water injection pump, a water return pump, a connecting pipe, a first one-way valve, a second one-way valve and a switching valve, the common end is communicated with a working cavity of the flexible ureteroscope body, the first branch end is connected with a water injection pump through a first one-way valve, and the second branch end is connected with a water return pump through a second one-way valve; the switching valve is used for selectively communicating the common end with the first branch end or the second branch end, and automatic alternation of water injection and pumpback is achieved. A passage is selected through the switching valve, and automatic alternation of water injection and pumpback is achieved; the first one-way valve and the second one-way valve prevent backflow and ensure that liquid sources are clean; through transient flushing of the system, clear view is ensured; the pressure of the pelvis is accurately controlled through in-vitro pressure monitoring, the infection risk is reduced, and the operation safety and efficiency are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a hydraulic control system for a pediatric sheathless flexible ureteroscope. Background Technology

[0002] Children's ureters are much thinner than adults', making it often impossible to insert a ureteral sheath. In flexible ureteroscopic lithotripsy without a sheath, clinicians face a dilemma: to ensure a clear surgical field, a fluid infusion and return cycle needs to be established. However, when fluid is injected into the renal pelvis, the lack of a sheath for return can cause a rapid increase in intrapelvic pressure, increasing the risk of postoperative infection and kidney damage.

[0003] Currently, the common clinical practice is to use a manual "pulse-injection-absorption" cycle. This involves injecting water through the single channel of the flexible endoscope with a syringe, then aspirating the turbid fluid, discarding it, and repeating this process. This method has at least the following drawbacks:

[0004] 1. Manual operation is cumbersome. A single lithotripsy surgery requires hundreds of cycles of water injection and aspiration, requiring an assistant to operate the entire procedure, which severely slows down the surgical process, prolongs anesthesia time, and increases anesthesia-related risks.

[0005] 2. During manual operation, the extracted fluid may occasionally be regurgitated, increasing the probability of retrograde infection.

[0006] 3. During the injection process, due to the lack of intrarenal pelvic pressure monitoring, it is difficult to accurately control the injection volume and injection speed each time, and the increased intrarenal pelvic pressure increases the risk of infection.

[0007] While there are existing automatic water injection devices for adult ureteroscopes, most of these devices rely on the reflux channel provided by the ureteral sheath to achieve fluid circulation, which is not suitable for pediatric sheathless surgery scenarios. Therefore, it is necessary to design a hydraulic control system for pediatric sheathless flexible ureteroscopes to solve at least one of the problems existing in the above-mentioned prior art. Summary of the Invention

[0008] The present invention aims to provide a hydraulic control system for a pediatric sheathless flexible ureteroscope, in order to solve at least one of the problems existing in the prior art.

[0009] This invention provides a hydraulic control system for a pediatric flexible ureteroscope without a sheath, comprising: The body of a flexible ureteroscope; The external hydraulic control unit includes an injection pump, a return pump, a connecting pipe, a first check valve, a second check valve, and a switching valve; The water injection pump inlet is connected to the cleaning fluid container, and the return water pump outlet is connected to the waste liquid collection container; the connecting pipe has a common end and a first branch end and a second branch end, and the common end is connected to the working cavity of the ureteroscope body; the first one-way valve is located between the water injection pump and the first branch end, allowing only liquid to flow from the water injection pump to the connecting pipe; the second one-way valve is located between the return water pump and the second branch end, allowing only liquid to flow from the connecting pipe to the return water pump; the switching valve is used to selectively connect the common end to the first branch end or the second branch end.

[0010] The hydraulic control system for a pediatric sheathless ureteroscope provided by the present invention further includes a pressure monitoring unit, which is disposed on the pipeline between the common end and the working cavity, for monitoring the liquid pressure in the working cavity.

[0011] The hydraulic control system for a pediatric sheathless ureteroscope provided by the present invention further includes a central control unit, which is electrically connected to the injection pump, the return pump, the switching valve, and the pressure monitoring unit.

[0012] According to the present invention, a hydraulic control system for a pediatric sheathless ureteroscope is provided, wherein the central control unit is configured to execute the following control logic: Before the surgery begins, the switching valve is controlled to connect the common end to the second branch end, and the return water pump is started to empty the fluid in the renal pelvis until the pressure monitoring unit reads zero. The switching valve is controlled to connect the common end to the first branch end, the water injection pump is started to inject water into the renal pelvis, and the pressure change is monitored by the pressure monitoring unit. When the pressure value reaches the preset safety threshold, the total water injection volume at this time is recorded as the safe perfusion volume V for a single cycle. During the surgical lithotripsy process, with the safe perfusion volume as the upper limit V, the switching valve is controlled to alternately connect the first branch end and the second branch end, and the water injection pump and the water return pump are started accordingly to realize automatic water injection-return circulation. Furthermore, during the water injection process, if the pressure value detected by the pressure monitoring unit reaches or exceeds the preset safety threshold, the water injection pump will be stopped immediately and an alarm signal will be issued.

[0013] According to the present invention, a hydraulic control system for a pediatric sheathless ureteroscope is provided, wherein the central control unit is further configured to: dynamically adjust the flow rate of the water injection pump based on the real-time reading of the pressure monitoring unit during the water injection process; and during the aspiration process, if the pressure monitoring unit displays that the negative pressure continuously exceeds a preset safety threshold, it is determined that the pipeline is blocked and an alarm is issued.

[0014] According to the present invention, a hydraulic control system for a pediatric sheathless ureteroscope is provided, wherein the central control unit is further configured to: after each aspiration, control the switching valve to connect the first branch end and start the water injection pump to flush the working cavity.

[0015] According to the present invention, a hydraulic control system for a pediatric sheathless ureteroscope is provided, wherein the inlet of the waste fluid collection container is provided with a filter screen for filtering stone powder.

[0016] According to the present invention, a hydraulic control system for a pediatric sheathless ureteroscope is provided, wherein both the injection pump and the return pump are peristaltic pumps.

[0017] It should be noted that although this invention supports fully automated water injection-aspiration circulation, considering the complexity of the renal calyx anatomy in children (such as the renal pelvis being connected to multiple renal calyces, similar to "a living room connecting multiple bedrooms"), in actual operation, when the flexible endoscope probe is located in a certain renal calyx, continuous negative pressure aspiration may cause the mucosa within that calyx to close, thereby blocking fluid flow and increasing the risk of mucosal damage. Therefore, this invention also designs a semi-automatic or manual intervention mode, allowing the surgeon to control the start and stop of aspiration in real time via a foot switch or hand button. Similarly, the water injection process can also be manually triggered by the surgeon, especially in infantile stone surgery, where the single injection volume is only about 20ml. Manual control, starting during lithotripsy and stopping when adjusting the angle, can significantly improve the effectiveness of water injection and surgical efficiency.

[0018] Compared with the prior art, the beneficial effects of this application are as follows: This invention achieves automated water injection and aspiration by coordinating the injection pump, return pump, and switching valve, replacing cumbersome manual operations, reducing anesthesia exposure time, lowering anesthesia-related risks, and freeing up an assistant to participate in other critical operations. A first one-way valve located between the injection pump and the connecting pipe prevents turbid liquid from flowing back into the injection pump and cleaning fluid container during aspiration, ensuring the cleaning fluid source remains clean. A second one-way valve located between the return pump and the connecting pipe prevents liquid from being ejected from the return pump side during injection, while also preventing the backflow of already extracted contaminated liquid. The switching valve's path selection ensures that injection and aspiration do not interfere with each other, guaranteeing the cleanliness of the injected liquid source from the outset and effectively reducing the probability of retrograde infection.

[0019] In addition, the present invention provides a manual intervention mode to meet the needs of delicate operation under complex renal calyx structures, avoid mucosal closure or damage caused by continuous negative pressure, and improve water injection efficiency, thereby further ensuring surgical safety and operational flexibility.

[0020] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a hydraulic control system for a pediatric sheathless flexible ureteroscope provided in an embodiment of the present invention; Figure 2 This is a partial structural schematic diagram of the external hydraulic control unit provided in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Ureteroscope body; 2. External hydraulic control unit; 21. Injection pump; 22. Return pump; 23. Connecting pipe; 24. First check valve; 25. Second check valve; 26. Switching valve; 27. Cleaning fluid container; 28. Waste fluid collection container; 29. ​​Filter screen; 3. Pressure monitoring unit. Detailed Implementation

[0024] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0025] Example This invention provides a hydraulic control system for a pediatric sheathless flexible ureteroscope. Please refer to [link to relevant documentation]. Figures 1-2The system includes: a flexible ureteroscope body 1 and an external hydraulic control unit 2. The external hydraulic control unit 2 includes an injection pump 21, a return pump 22, a connecting pipe 23, a first one-way valve 24, a second one-way valve 25, and a switching valve 26. The inlet of the injection pump 21 is fixedly connected to the top of the cleaning fluid container 27, and the outlet of the return pump 22 is fixedly connected to the top of the waste fluid collection container 28. The connecting pipe 23 has a common end and a first branch end and a second branch end. The common end is connected to the working cavity of the flexible ureteroscope body 1 through a pipeline. The first one-way valve 24 is located on the pipeline between the injection pump 21 and the first branch end, allowing only liquid to flow from the injection pump 21 to the connecting pipe 23. The second one-way valve 25 is located on the pipeline between the return pump 22 and the second branch end, allowing only liquid to flow from the connecting pipe 23 to the return pump 22. The switching valve 26 is used to selectively connect the common end to the first branch end or the second branch end.

[0026] In this embodiment, both the water injection pump 21 and the return pump 22 are peristaltic pumps. The inlet of the water injection pump 21 is connected to a cleaning solution container 27 containing physiological saline via a pipeline, and the outlet of the return pump 22 is connected to a waste liquid collection container 28 via a pipeline. A filter screen 29 for filtering gravel powder is installed at the inlet of the waste liquid collection container 28. The filter screen 29 has an L-shaped structure and is detachably connected to the side wall of the waste liquid collection container 28 by bolts. Both the cleaning solution container 27 and the waste liquid collection container 28 are detachably fitted with covers. When the cover on the top of the waste liquid collection container 28 is opened, the gravel powder intercepted on the filter screen 29 can be cleaned. The connecting pipe 23 is set as a Y-shaped structure, and the switching valve 26 is set as a three-way solenoid valve, installed at the fork of the Y-shaped connecting pipe 23.

[0027] In this invention, all hydraulic control components—injection pump 21, return pump 22, connecting pipe 23, first check valve 24, second check valve 25, and switching valve 26—are located externally. The ureteroscope body 1 is a conventional single-lumen flexible endoscope in the prior art. Through the coordinated operation of the injection pump 21, return pump 22, and switching valve 26, automated injection and aspiration are achieved, replacing cumbersome manual operation, reducing anesthesia exposure time, lowering anesthesia-related risks, and freeing up an assistant to participate in other key operations. The injection pump 21, return pump 22, and switching valve 26 are all located externally. The first check valve 24 between the connecting pipe 23 and the pump 24 prevents turbid liquid from flowing back into the water pump 21 and the cleaning fluid container 27 during backflow, ensuring that the cleaning fluid source is always clean. The second check valve 25 between the return pump 22 and the connecting pipe 23 prevents liquid from being ejected from the return pump 22 side during water injection, while also preventing the backflow of the already extracted contaminated liquid. The path selection of the switching valve 26 ensures that water injection and backflow do not interfere with each other, ensuring that the source of the injected liquid is clean from the source, effectively reducing the probability of retrograde infection.

[0028] Furthermore, it also includes a pressure monitoring unit 3, which is installed on the pipeline between the common end and the working chamber to monitor the liquid pressure in the working chamber; specifically, the pressure monitoring unit 3 is set as a high-precision pressure sensor.

[0029] By placing the pressure monitoring unit 3 between the common end of the connecting tube 23 and the working cavity of the flexible endoscope, the fluid pressure within the working cavity can be monitored in real time. An individualized "safe perfusion volume" for the renal pelvis is obtained through preoperative assessment, and the flow rate of the water pump 21 is dynamically adjusted based on pressure feedback during the procedure to consistently control the pressure within the renal pelvis within a safe threshold. This external pressure measurement method avoids many drawbacks of integrating sensors within the flexible endoscope, while achieving precise pressure control and effectively preventing postoperative infection and kidney damage.

[0030] Furthermore, it also includes a central control unit, which is electrically connected to the water injection pump 21, the return water pump 22, the switching valve 26, and the pressure monitoring unit 3. The central control unit can be configured as an STM32 series microcontroller with built-in control program; its control logic is as follows: Step S1: System initialization: Power on and perform a self-test to confirm that all components are working properly.

[0031] Step S2: Preoperative emptying and safe perfusion volume assessment: S21: The central control unit controls the switching valve 26 to connect the common terminal to the second branch terminal; S22: Start the return water pump 22 and draw water at a flow rate of 3 mL / min to empty the original fluid in the renal pelvis until the pressure monitoring unit 3 reads 0 and holds for 3 seconds to confirm. S23: Control switching valve 26 to connect the common end with the first branch end; S24: Start the water injection pump 21 at a low flow rate of 0.5 mL / min, while simultaneously acquiring the readings of the pressure monitoring unit 3 at a frequency of 10 Hz; when the pressure value rises to the preset safety threshold, immediately shut off the water injection pump 21, and record the total injection volume from the start of water injection to the pressure reaching the target, i.e., the safe perfusion volume V; if V < 5 mL, the system issues a warning indicating abnormal renal pelvis capacity; the preset safety threshold is 30-50 cm. 40cm is available .

[0032] Step S3: Automatic Circulation of Crushed Stone: S31: Control switching valve 26 to connect the common end with the first branch end; S32: Start the water injection pump 21 to inject water at a flow rate of 2 mL / min, while simultaneously acquiring the readings of the pressure monitoring unit 3 at a frequency of 10 Hz; during the water injection process, the central control unit continuously monitors the renal pelvis pressure. If the pressure value reaches or exceeds the preset safety threshold (e.g., 40 cm), the central control unit will detect the pressure. If the water pump 21 is stopped immediately and an audible and visual alarm is issued, the switching valve 26 can be switched to the second branch end, and the return water pump 22 can be started for emergency back suction to quickly reduce the pressure in the renal pelvis. S33: If the pressure does not exceed the limit during the water injection process, when the water injection volume reaches... At that time, stop water pump 21; S34: After a delay of 0.3 seconds, control switching valve 26 to connect the common terminal to the second branch terminal; S35: Start the return water pump 22, and pump back at a flow rate of 3 mL / min for a duration of [duration missing]. Take a few seconds to ensure that the injected liquid is completely evacuated; S36: Stop the return water pump 22 to complete one cycle; after a 0.5-second interval, begin the next cycle; this process continues until the crushing is complete.

[0033] Step S3a: Manual / Semi-automatic operation mode (optional) Considering the complexity of the renal calyx structure and the need for real-time intraoperative assessment during clinical procedures, this system can also be switched to a manual intervention mode. In this mode, the initiation of water injection and aspiration is no longer automatically cycled by the central control unit, but is actively controlled by the surgeon (e.g., via a foot switch or handheld button). For example: (1) The surgeon presses the water injection button during the lithotripsy process, and the system injects water at a preset flow rate; (2) Stop adding water when it is necessary to adjust the position of the lens or replace the renal calyx; (3) After entering the new cup, press the back suction button to aspirate the liquid. If mucosal closure or abnormal negative pressure is observed, the surgeon can stop the back suction immediately to avoid mucosal damage.

[0034] This mode retains the precise control capabilities of automated systems while providing surgeons with greater operational flexibility and safety, making it particularly suitable for pediatric patients with complex anatomical structures and limited operating space.

[0035] It should be noted that the system has a manual control interface on the panel of the external hydraulic control unit 2 for connecting a foot switch or a hand button; both the foot switch and the hand button are normally open contact switches with a waterproof design and meet medical electrical safety standards.

[0036] The foot switch features a dual-pedal design (one for filling water and one for retraction). Each pedal contains an independent normally open micro switch, with shielded cables leading out from both ends and connecting to the I / O expansion board of the central control unit.

[0037] The handheld button features a dual-button design, with internal tactile switches that connect to the central control unit via a multi-core cable.

[0038] All switch signal lines use opto-isolated input modules to isolate external interference and ensure the stability and safety of the control system.

[0039] The system supports manual / semi-automatic mode, allowing the surgeon to directly control the water injection and aspiration processes via a foot switch or handheld button. The central control unit executes the following logic based on the button status: (1) The system is equipped with a mode switch, which can select "fully automatic mode" or "manual intervention mode". When manual intervention mode is selected, the automatic cycle is paused, and the central control unit only responds to manual input signals.

[0040] (2) When the surgeon presses the "inject water" button (foot pedal or handheld), the central control unit detects the signal, first confirms that it is not in the current state of aspiration (interlock protection), then controls the switching valve 26 to connect the common end with the first branch end, and at the same time starts the water injection pump 21 to inject water at the preset flow rate; When the surgeon releases the button, the central control unit stops the water pump 21 and resets the switching valve 26 to the middle position.

[0041] (3) When the surgeon presses the “retract” button, the central control unit detects the signal and confirms that it is not in the water injection state. Then it controls the switching valve 26 to connect the common end with the second branch end and starts the return water pump 22 to retract at the preset flow rate. Releasing the button stops the retraction and resets the switching valve 26.

[0042] (4) If the surgeon accidentally steps on two pedals or presses two buttons at the same time, the central control unit will stop all actions first and issue a warning sound to ensure that water injection and aspiration will not cause abnormal pipeline pressure at the same time. In manual intervention mode, pressure monitoring unit 3 continues to work. If the renal pelvis pressure exceeds the safety threshold, the system will automatically stop the infusion and switch to aspiration, while issuing an audible and visual alarm to ensure patient safety.

[0043] In addition, the central control unit displays the current working mode (automatic / manual), water injection / retraction status, renal pelvis pressure value, etc. in real time through LED indicators or LCD screens on the panel, making it easy for the surgeon to understand the system status.

[0044] Step S4: Intraoperative monitoring and abnormality management: (1) During the water injection process, if the reading of pressure monitoring unit 3 exceeds 45cm Immediately stop water injection and initiate emergency pumping. (2) During the retraction process, if the pressure monitoring unit 3 displays a negative pressure that lasts for more than 10 seconds (e.g., below -20cm), The system determines that the pipeline is blocked and issues an audible and visual alarm.

[0045] Step S5: Intermittent flushing To reduce powder residue in the working cavity, after each aspiration and before the start of the next cycle, the switching valve 26 can be briefly activated to turn on the water pump 21, injecting water at a flow rate of 0.5 mL / min for 0.5-1 seconds to push residual powder into the renal pelvis. Then, the next aspiration should be performed immediately to remove the pushed-in residual powder. This brief flushing after each aspiration removes residual stone fragments from the working cavity, ensuring the fluid entering the renal pelvis during the next injection is clean. This prevents repeated flushing of the field of view by stone fragments, significantly improving lithotripsy accuracy and surgical continuity.

[0046] Furthermore, since the flow of fluid in the pipeline during water injection will cause a pressure drop, the reading of pressure monitoring unit 3 will be slightly higher than the actual pressure of the renal pelvis. Therefore, in this embodiment, the central control unit also has a built-in pressure drop model based on flow rate and pipeline characteristics to calculate and display the compensated renal pelvis pressure value in real time, making pressure control more accurate.

[0047] This invention uses a switching valve 26 to select the flow path, enabling automatic alternation of water injection and aspiration. A pressure sensor monitors the working cavity pressure in real time. A central controller controls the water injection pump 21, the return pump 22, and the switching valve 26 based on pressure feedback. Preoperative assessment of the safe perfusion volume for the renal pelvis is conducted, and intraoperative automatic water injection-aspiration is performed while monitoring for abnormalities. The first one-way valve 24 and the second one-way valve 25 prevent backflow, ensuring a clean fluid source. Brief system flushing ensures a clear field of vision. External pressure monitoring precisely controls the renal pelvis pressure, reducing the risk of infection and significantly improving surgical safety and efficiency.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydraulic control system for a pediatric sheathless flexible ureteroscope, characterized in that, include: Ureteroscopic body (1); The external hydraulic control unit (2) includes a water injection pump (21), a water return pump (22), a connecting pipe (23), a first check valve (24), a second check valve (25), and a switching valve (26). The inlet of the water injection pump (21) is connected to the cleaning fluid container (27), and the outlet of the return water pump (22) is connected to the waste liquid collection container (28). The connecting pipe (23) has a common end and a first branch end and a second branch end. The common end is connected to the working cavity of the ureteroscope body (1). The first one-way valve (24) is located between the water injection pump (21) and the first branch end, allowing only liquid to flow from the water injection pump (21) to the connecting pipe (23). The second one-way valve (25) is located between the return water pump (22) and the second branch end, allowing only liquid to flow from the connecting pipe (23) to the return water pump (22). The switching valve (26) is used to selectively connect the common end to the first branch end or the second branch end.

2. The hydraulic control system for a pediatric sheathless ureteroscope according to claim 1, characterized in that, It also includes a pressure monitoring unit (3), which is installed on the pipeline between the common end and the working cavity, and is used to monitor the liquid pressure in the working cavity.

3. The hydraulic control system for a pediatric sheathless flexible ureteroscope according to claim 2, characterized in that, It also includes a central control unit, which is electrically connected to the water injection pump (21), the return water pump (22), the switching valve (26), and the pressure monitoring unit (3).

4. The hydraulic control system for a pediatric sheathless flexible ureteroscope according to claim 3, characterized in that, The central control unit is configured to execute the following control logic: Before the surgery begins, the switching valve (26) is controlled to connect the common end to the second branch end, and the return water pump (22) is started to empty the fluid in the renal pelvis until the pressure monitoring unit (3) reads zero. Control the switching valve (26) to connect the common end with the first branch end, start the water injection pump (21) to inject water into the renal pelvis, and at the same time monitor the pressure change through the pressure monitoring unit (3). When the pressure value reaches the preset safety threshold, record the total water injection volume at this time as the safe perfusion volume V for a single cycle. During the surgical lithotripsy process, with the safe perfusion volume as the upper limit of V, the switching valve (26) is controlled to alternately connect the first branch end and the second branch end, and the water injection pump (21) and the water return pump (22) are started accordingly to realize automatic water injection-return circulation; Furthermore, during the water injection process, if the pressure value detected by the pressure monitoring unit (3) reaches or exceeds the preset safety threshold, the water injection pump (21) will be stopped immediately and an alarm signal will be issued.

5. A hydraulic control system for a pediatric sheathless ureteroscope according to claim 4, characterized in that, The central control unit is also configured to: dynamically adjust the flow rate of the water injection pump (21) according to the real-time reading of the pressure monitoring unit (3) during the water injection process; and if the pressure monitoring unit (3) shows that the negative pressure continues to exceed the preset safety threshold during the pumping process, it is determined that the pipeline is blocked and an alarm is issued.

6. A hydraulic control system for a pediatric sheathless flexible ureteroscope according to claim 4, characterized in that, The central control unit is also configured to: after each back-pull, control the switching valve (26) to connect the first branch end and start the water injection pump (21) to flush the working cavity.

7. A hydraulic control system for a pediatric sheathless flexible ureteroscope according to claim 1, characterized in that, The waste liquid collection container (28) is equipped with a filter screen (29) for filtering gravel powder at its inlet.

8. The hydraulic control system for a pediatric sheathless flexible ureteroscope according to claim 1, characterized in that, Both the water injection pump (21) and the water return pump (22) are peristaltic pumps.

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