Resectoscope with distal electrode guidance

Abstract

The present invention relates to an electroresectoscopic scope with distal electrode guidance. The electroresectoscopic scope is used for endoscopic surgery and has a tubular shaft and a handle, wherein the shaft includes an electrode instrument arranged to move longitudinally and includes an electrically insulating insulating insert at its distal end, wherein the electrode instrument has an elongated shaft with one or two brackets and has an electrode capable of receiving high-frequency current in its distal end, and is characterized in that the insulating insert has one or more guides for holding a bracket, wherein the bracket can move longitudinally in the guide.

Description

Technical Field

[0001] The present invention relates to a resectoscope for use in endoscopic surgery. Background Art

[0002] This type of resectoscope is used in urology, especially in surgical procedures within the bladder and urethra. They are generally used to remove and gasify tissue, such as tissue within the lower urethra. For this purpose, the resectoscope includes a longitudinally movable electrosurgical electrode instrument, which can be removed from the distal end of the resectoscope shaft tube after the resectoscope is inserted with its working distal end. In addition, the resectoscope generally includes an optical system for observing the surgical site and monitoring the outer surgery, which includes an objective lens at the distal end and is connected to an eyepiece or an electronic monitoring unit for direct observation at the proximal end. Finally, the resectoscope includes a lighting element, mostly in the form of an optical fiber bundle, in order to illuminate the surgical site, which tightens the resectoscope shaft and is connected to a light source at its proximal end.

[0003] The electrode instrument passing through the resectoscope shaft can include an electrosurgical electrode in the form of a ring (annulus) or a vaporizing button (plasma button) at its distal working end. Such an instrument is, for example, the OES PRO resectoscope (Olympus), which is a resectoscope described in DE102019102841A1 and US4,917,082A. The electrode instrument can be designed as a bipolar instrument or a monopolar instrument, wherein a bipolar instrument can have significant safety advantages over a monopolar instrument.

[0004] The electrode instrument can be moved longitudinally in the instrument shaft to achieve tissue resection by means of the distal electrode. In order to ensure that the electrode instrument is guided straight through the instrument shaft, the electrode instrument generally has a guide piece on its long rod portion, and the guide piece supports the electrode instrument on the surface of the optical component or on the inner wall of the resectoscope shaft. For this purpose, the guide piece is usually designed to be complementary to the optical component or the inner wall is partially circular, for example, in the form of a partially circular guide plate.

[0005] Since common electrode instruments have a relatively long stroke of, for example, 23 millimeters, the guide is generally also spaced away from the distal end of the electrode instrument. In this way, it is ensured that the guide also remains in the resectoscope shaft when the electrode instrument is moved away to the maximum extent distally. However, the large distance between the guide and the distal electrode causes the electrode instrument to bend in this area and thus the electrode can be moved or even bent relative to the resectoscope shaft. In addition, the positioning of the electrode instrument that has been bent distally cannot be corrected.

[0006] Because the distal end of the resectoscope rod is often used as a tissue cutting blade in surgical operations, it is important to accurately guide the electrode position relative to the edge of the distal end of the resectoscope rod. Only good cutting results can be obtained. Small inaccuracies in the straightness of the electrode instrument may already have an adverse effect on the cutting performance of the electrode instrument. If the loop electrode is positioned too deep, direct contact between the electrode and the rod tip may cause electrode damage. Therefore, the loop can, for example, remain hooked on the rod tip or the insulating insert when withdrawn and bend or even break. It is also conceivable that material damage occurs on the rod. If the loop electrode is positioned too high, the resectoscope rod may be omitted as a cutting blade and at least make tissue cutting difficult. Summary of the invention

[0007] It is therefore an object of the present invention to provide a resectoscope whose electrode instrument is significantly stabilized at its distal end.

[0008] The object is achieved by a resectoscope and by an electrode system.

[0009] The present invention, in particular, in a first aspect, relates to an electrosurgical resectoscope for endoscopic surgery, comprising a tubular rod and a handle, wherein the rod includes an electrode instrument which can be longitudinally movably arranged and includes an electrically insulating insulating insert at its distal end, wherein the electrode instrument has an elongated rod portion with one or two support arms and has an electrode which can withstand the action of high-frequency current in its distal end, and is characterized in that the insulating insert has one or more guide members for respectively holding a support arm, wherein the support arm can be longitudinally moved in each guide member.

[0010] According to the present invention, a stabilizing guide is placed in an insulating insert at the distal end of the resectoscope rod, so that the distance between the front end of the electrode and the guide is reduced to a minimum, thereby achieving a more reliable positioning of the electrode. When the electrode instrument moves longitudinally, the guide no longer moves together. The electrode system is thus much more stable overall and is protected against bending. In addition, a more precise cutting can also be achieved using a slightly curved electrode instrument, because the electrode is guided to the correct position relative to the rod end blade by the guide during cutting. Therefore, the cutting result is significantly improved overall.

[0011] The resectoscope of the present invention has a tubular rod according to a common design mode. The endoscope rod comprises an elongated sleeve tube. In addition to the rod portion, the resectoscope also comprises a handle which is usually composed of two handle portions for holding and operation.

[0012] The shaft of the resectoscope has an electrode instrument which is arranged to be longitudinally displaceable. The electrode instrument is used as a through instrument in such a resectoscope and can be designed for single use or multiple use.

[0013] The electrode instrument has an elongated rod (rod member) and is designed as a straight-through instrument for a resectoscope, i.e., an instrument that can be inserted into a body opening through a resectoscope rod tube. The electrode instrument has an electrode at its distal end that can withstand high-frequency current. The electrode can be a cutting ring, a vaporization button (plasma button) or other electrodes commonly found on the market. The electrode is preferably a cutting ring electrode. Corresponding electrodes and electrode instruments are known to technical experts.

[0014] The electrode instrument may be a bipolar electrode instrument, which includes an electrode as part of an electrode assembly. In this case, the electrode instrument, for example, includes a second electrode in the distal end of the electrode instrument, which is designed as a neutral electrode. Alternatively, the second electrode (neutral electrode) may also be arranged on other elements of the distal end of the resectoscope. Obviously, the electrode instrument may also be designed as a monopolar instrument.

[0015] The electrode instrument can be moved longitudinally in the resectoscope rod, that is, it can be moved distally and proximally in the axial direction. In order to be connected to the resectoscope, the electrode instrument has an elongated rod, which can be fixed at its proximal end on a slide included in the resectoscope to produce a motion-associated connection. The slide generally slides on a tube and is held in a static position by a spring preloaded by a spring unit. Therefore, the electrode can be moved distally toward the tissue to be cut or away from the tissue to be cut without having to move the entire resectoscope. In addition, the longitudinal movability of the electrode instrument allows the tissue to be clamped between the electrode and the insulating insert and removed from the surgical site. Therefore, the distal end of the resectoscope rod or the insulating insert and the electrode move closer and apart by means of the longitudinal movement possibility of the electrode instrument.

[0016] The electrode instrument has one or two elongated support arms, which form the rod of the electrode instrument. The present invention preferably has an electrode instrument with two support arms. If the electrode instrument has only one support arm, the electrode is arranged at its distal end. If the electrode instrument has two support arms, they are connected to each other at their distal ends by a connecting piece. The connecting piece can, for example, form the electrode, or the electrode can be arranged on the connecting piece. In other words, the support arm carries the electrode or the connecting piece carrying the electrode. This or these support arms are preferably elongated. If the electrode instrument has two support arms, they extend substantially parallel to each other. At this time, the two support arms can, for example, extend along the inner wall of the inner tube or the sheath tube of the resectoscope and be spaced apart from each other by about 120°-200° along the inner circumference of the inner wall, preferably by about 180°. Therefore, it is preferred that the two support arms are roughly opposite, wherein the longitudinal axis of the resectoscope rod represents the center point between the two support arms.

[0017] In addition to the electrode instrument, the resectoscope rod has an insulating insert at its distal end. The insulating insert is designed to be non-conductive, i.e. electrically insulating. In this way, the insulation of the active electrode relative to the conductive resectoscope rod is ensured. For this purpose, the insulating insert is preferably completely, but at least to the extent that the insulating properties of the insert are ensured, made of a non-conductive, i.e. electrically insulating material. Such materials are known to technical experts and include, for example, ceramic materials and plastics. According to the present invention, insulating inserts made of plastic are particularly preferred because of their relatively low production costs and good insulating properties. Since the insulating insert can come into contact with the plasma that occurs during electrosurgery with the aid of electrodes, heat-resistant plastics are particularly preferred. Heat-resistant plastics can withstand the high temperatures that occur in the far front end region of the resectoscope without damage. Suitable heat-resistant plastics can, for example, be selected from the group consisting of fluorinated polymers and cycloolefin copolymers. The insulating insert made of plastic can be manufactured by injection molding.

[0018] The insulating insert is suitable for being detachably connected to the distal end of the resectoscope shaft. This means that the insulating insert and the end are at least partially complementary in shape and size. As a result, the insulating insert can be connected to the end. The connection must be fixed or locked in such a way that the insulating insert is prevented from coming out during the operation of the outer shell. Thus, the insulating insert with a cylindrical section can be, for example, placed on an inner tube or a sheathing tube, the inner tube being inserted therein or it being inserted between the inner tube and the sheathing tube.

[0019] The insulating insert has a hollow section with an elongated cavity for passing through instruments. The section is arranged in the proximal end of the insulating insert. It ensures that the straight-through instruments passing through the resectoscope rod can pass through the channel-shaped interior of the insulating insert. The insulating insert can have a substantially cylindrical shape or at least a substantially cylindrical proximal portion. Accordingly, the cavity in the hollow section can have a hollow cylindrical shape.

[0020] The insulating insert of the invention has one or more guides for holding a support arm, i.e., 1, 2 or more guides. The invention preferably has an insulating insert with two guides. In other words, each guide is designed to hold a support arm. If the electrode device has two support arms, the insulating insert also includes two corresponding guides. If the electrode device has only one support arm, the insulating insert only includes one corresponding guide.

[0021] A support arm assigned to the guide member is mounted longitudinally movably in the guide member, and the support arm and thus the electrode instrument are held therein in such a manner that movement in the longitudinal direction of the resectoscope shaft is possible. At the same time, the guide member prevents the support arm from moving in other directions, that is, preventing movement in a direction other than the longitudinal direction of the resectoscope shaft, for example, in a transverse (radial) direction to the longitudinal direction.

[0022] In order to stabilize the electrode device, the guide(s) are arranged as closely as possible at the distal end of the insulating insert. The distance between the distal end of the rod and the guide(s) may be, for example, 1.5 cm or less, 1 cm or less, 0.5 cm or less, or 0.25 cm or less. The distance is preferably 0.5 cm or less.

[0023] The guide element(s) are arranged on the inner wall of the insulating insert. The guide elements are arranged and designed in such a way that they do not interfere with or only insignificantly interfere with the visual axis of the optical component. The guide element is generally designed approximately parallel to the longitudinal axis (LS) of the resectoscope rod, i.e. the longitudinal axis (LF) of the guide element(s) is / are approximately parallel to the longitudinal axis (LS) of the rod. At the same time, the guide element(s) extends from the inner wall of the insulating insert into the inner cavity of the insulating insert, preferably at an angle in the range of 140°-40°, preferably in the range of 110°-70°, more preferably at an angle of approximately 90° relative to the inner wall of the insulating insert. In this case, the guide element preferably does not extend into the instrument region distal to the distal end of the optical component or to the distal end of one of the support arms.

[0024] The guide element can be made of the same insulating material as the insulating insert, ie, for example, of a ceramic material. Alternatively, however, a guide element made of the aforementioned heat-resistant plastic is also conceivable. Preferably, the guide element is designed to be integral with the remainder of the insulating insert.

[0025] This or these guides then surround the respective support arm as described elsewhere in this document in such a way that the longitudinal movability of the support arm is ensured while preventing the support arm from moving in other directions, for example transversely to the longitudinal direction of the resectoscope rod. This can be done in that the guide surrounds the respective support arm over a range of 90° and more, preferably over a range of 180° and more, for example over a range of 240° and more, of its circumference. However, it may be advantageous for the simple installation of electrodes in a rod with a fixedly mounted insulating insert to keep the degree of enclosure small. A portion of the inner wall of the insulating insert that also adjoins and surrounds the respective support arm is considered to be part of the guide. Therefore, if the inner wall of the insulating insert adjoins the outer circumference of the support arm over a range of 20° and the extrusion protruding from the inner wall adjoins another 120° of the support arm, then the guide consisting of a portion of the inner wall and the extrusion surrounds the support arm over a range of 140°.

[0026] In one embodiment, it is contemplated that the guide does not completely surround the support arm corresponding to it. In this way, the support arm can be removed from the guide from the side as needed and also inserted into the guide from the side for installation. To this end, the guide can have flexibility that is sufficient to remove the support arm from the guide by slightly bending the guide. In this embodiment, the guide surrounds the support arm in a range of 90°-240° of its circumference, preferably in a range of 180°-240°. This embodiment is particularly suitable for installing an electrode instrument in a resectoscope, which has an insulating insert fixedly connected to the resectoscope rod. The electrode instrument can be designed for single use, and the remainder of the resectoscope, including the insulating insert, can be designed for multiple uses and recycling (cleaning).

[0027] In an alternative embodiment, the guide is surrounded by the support arm in such a way that the support arm cannot be removed from the guide without damaging the guide. This may be meaningful, for example, when the insulating insert is to be part of an electrode system designed for single use. In this embodiment, the insulating insert is also designed for single use. In this and other embodiments, the guide surrounds the respective support arm completely over 180° and more of its circumference, preferably over 240° and more, for example 360°.

[0028] Correspondingly, in a similar aspect, the present invention also relates to an electrode system preferably designed for single use to be used in an electroresectoscope for endoscopic surgery, comprising the insulating insert described herein and the electrode instrument described herein. Specifically, this aspect relates to an electrode system, characterized in that it comprises an electrode instrument and an electrically insulating insulating insert, wherein the electrode instrument comprises an elongated shaft with one or two arms and comprises an electrode capable of withstanding high-frequency current in its distal end, and wherein the insulating insert has one or more guides for holding a respective arm of the electrode instrument, wherein the respective arm is longitudinally movably arranged in the guide.

[0029] This electrode system can be used in the resectoscope of the present invention, but is sold separately from the resectoscope.Therefore, the electrode system can be designed for single use, for example.

[0030] The guide or guides of the electrode system surround the respective support arm over 180° or more, preferably 240° or more, and most preferably 360° of its circumference. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Embodiments of the present invention are schematically shown in the accompanying drawings, in which:

[0032] Figure 1A schematic side cross-sectional view of a resectoscope from the prior art is shown, which includes an electrode instrument with a guide mounted on the electrode instrument;

[0033] Figure 2 A schematic side cross-sectional view of a resectoscope according to the present invention is shown, which has an insulating insert with a guide for an electrode instrument support arm;

[0034] Figure 3 A schematic side cross-sectional view of the distal end of a resectoscope from the prior art is shown, which includes an electrode instrument with a guide mounted on the electrode instrument and supported on an optical assembly of the system;

[0035] Figure 4 A schematic side cross-sectional view of the distal end of the resectoscope of the present invention is shown, which has an insulating insert with a guide (shown in dashed lines) for an electrode instrument support arm;

[0036] Figure 5 A schematic front view of a shaft of a resectoscope according to the invention is shown, which has an insulating insert with a guide for an electrode instrument support arm;

[0037] Figure 6 A schematic front view of an alternative resectoscope shaft according to the invention is shown, which has an insulating insert with a guide for an electrode instrument support arm and in which the support arm extends between an inner tube and a sheathing tube and in which the guide does not completely surround the support arm;

[0038] Figure 7 A schematic front view of a shaft of an alternative resectoscope according to the invention having an insulating insert with a guide for an electrode instrument support arm and wherein the support arm extends between the inner tube and the enveloping tube and the guide does not completely surround the support arm; and

[0039] Figure 8 A schematic side cross-sectional view of the distal end portion of an electrode system according to the invention is shown, comprising an insulating insert with a guide (shown in dashed lines) for a bracket of an electrode instrument and a corresponding electrode instrument. DETAILED DESCRIPTION

[0040] Other advantages, features and characteristics of the present invention will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described.

[0041] Figure 1 A schematic side sectional view of a resectoscope 10 from the prior art is shown, in which an insulating insert 18 is arranged on an inner tube 40 , and a guide 26 is arranged on its electrode instrument 16 , which is supported on an optical assembly (not shown) inside the inner tube 40 . Figure 3 A schematic side cross-sectional view of the distal end of a resectoscope 10 from the prior art is shown.

[0042] The resectoscope 10 has a shaft 12, which includes a sheath tube 38 (outer tube) shown in dashed lines. An inner tube 40 extends in the sheath tube 38, and an electrode instrument 16 and Figure 3 The optical assembly 42 shown and the illumination means (not shown), for example in the form of an optical fiber bundle, extend in the inner tube 40. In addition, other elements (not shown here) may extend in the resectoscope, such as, for example, a separate irrigation tube, etc. The sheath tube 38 comprises, in a manner not shown here, a plurality of openings in its distal end, through which dirty irrigation fluid can flow into the gap between the sheath tube 38 and the inner tube 40 and flow away via the resectoscope shaft 12.

[0043] As in Figure 1 in and Figure 3 As can be seen in the enlarged detail view of FIG. 1 , the electrode instrument 16 in this conventional instrument should be protected against displacement deviating from the longitudinal direction of the rod 12 (e.g. transversely to the longitudinal direction) by means of a guide 26 with a partially circular cross section. The electrode instrument 16 is mounted in the inner tube 40 so as to be longitudinally movable. The guide 26 is designed to be complementary in shape to the outer wall of the optical component 42 and has a partially cylindrical shape. The guide 26 is fixed in the rod 20 of the electrode instrument 16 to two brackets (fork tubes) 22 ( Figure 5 The support arm 22 extends closely within the resectoscope shaft 12 and diverges only within the distal end of the resectoscope shaft 12 in order to accommodate an electrode 24 in the form of a loop electrode between its ends. The guide 26 of the electrode instrument 16 does not help to resist displacement of the electrode instrument 16 in the area distal to the guide 26.

[0044] The electrode instrument 16 can be forcibly guided to move axially toward the distal and proximal sides by the operation of the handle 14. At this time, it can move beyond the distal ends of the inner tube 40 and the sheath tube 38. Therefore, the surgeon is allowed to operate tissue further away from the front tip of the resectoscope. For this reason, the inner tube 40 and / or the electrode instrument 16 can also be mounted rotatably around its longitudinal axis. The electrode instrument 16 has an electrode 24 at its distal end, which is designed as a cutting ring and can remove tissue by electrosurgical ablation. In this case, a high-frequency voltage is applied to the electrode 24 to cut the tissue.

[0045] The resectoscope 10 shown has a passive transport mechanism, in which the slide 36 is moved in the distal direction toward the distal first handle portion 32 by the relative movement of the handle portions 30 and 32 arranged on the proximal side of the resectoscope rod 12, overcoming the spring force applied by the spring bridge 34. When the slide 36 moves toward the handle portion 32 in the distal direction, the electrode instrument 16 is forcibly guided to move toward the distal side in a manner not shown. When the force on the handle portions 30 and 32 is removed, the spring force generated by the spring bridge 34 forces the slide 36 to return to its rest position, where the electrode instrument 16 is pulled toward the proximal direction. When the slide 36 moves back, the electrosurgery operation with the electrode instrument 16 can be completed passively without the need for the surgeon's hand force.

[0046] The insulating insert 18 of the resectoscope 10 is inseparably bonded to it at its distal end. The insulating insert 18 does not contain a guide member. It is made of an electrically insulating ceramic material.

[0047] Figure 2 and Figure 4 FIG. 2 shows a schematic cross-sectional side view of the resectoscope 10 of the present invention. Figure 1 and Figure 3 The difference of the resectoscope shown is that the guide 26 for stabilizing the longitudinal movement of the electrode instrument 16 is not arranged on the shaft 20 of the electrode instrument 16, but on the inner wall 28 of the insulating insert 18. By arranging the guide 26 in the insulating insert 18, the maximum distance between the guide 26 and the electrode 24 is reduced to a minimum. The risk of bending of the distal end of the electrode instrument 16 is thereby significantly reduced, even when the electrode instrument 16 is moved to the maximum extent in a distal direction. The guide 26 is spaced apart from the distal end of the insulating insert 18 by approximately 0.5 cm. The longitudinal axis (LF) of the guide is now approximately parallel to the longitudinal axis (LS) of the shaft. Figure 4 It can be seen that the guide member 26 is designed to be elongated in the longitudinal direction of the rod 12 .

[0048] In showing Figure 2 and Figure 4 Part of the same resectoscope 10 Figure 5 In the schematic diagram of the front view of the rod 12, it can be seen that the electrode device 16 has two brackets 22, between which the electrode 24 in the form of a loop electrode is held at the distal end. The brackets 22 are passed through by conductive metal wires in their interior and also include an insulating layer covering the metal wires, which electrically isolates the brackets 22 from the outside. In addition, the inner tube 40 has an optical component 42 extending between the brackets 22.

[0049] It can also be seen that the insulating insert 18 arranged at the distal end of the resectoscope rod 12 has two guides 26. When viewed from the sagittal plane of the insulating insert 18, the guides 26 are opposite to each other. Each of the two support arms 22 of the electrode instrument 16 extends through a guide 26 of the insulating insert 18. The guides 26 are complementary in shape at least partially to the support arms 22 for the sake of saving space. The guides 26 are each partially circular, and their ends are connected to the inner wall 28 of the insulating insert 18. In the embodiment shown, the guides 26 and the insulating insert 18 are formed in one piece from an electrically insulating ceramic material. The guides 26 completely surround the respective support arms 22, i.e., over a 360° range of their circumference.

[0050] Figure 6 A schematic front view of a shaft 12 of an alternative resectoscope 10 according to the invention is shown, which has an insulating insert 18 with a guide 26 for the support arm 22 of the electrode instrument 16. Figure 5 The difference of the resectoscope shown is that the support arm 22 of the electrode instrument 16 is not arranged inside the inner tube 40, but between the inner tube 40 and the sheath tube 38. In addition, the guide member 26 is different from the Figure 5 The guide 26 is shown as not completely surrounding the support arm 22. Each guide 26 has a notch, which can be used for the lateral insertion of the support arm 22. For this reason, the guide 26 is soft enough to allow the notch to expand during loading and unloading without bending or breaking. The notch in the guide 26 is formed in the direction of the optical component or in the direction of the second support arm 22 in the embodiment shown. The notches of the two guides 26 are therefore opposite to each other. The notch extends through the entire length of the guide 26 in the longitudinal direction of the instrument in a manner not shown here.

[0051] Figure 7 Shown as Figure 6 An alternative design of the support arm 22 is not designed to completely surround the guide member 26. The guide member 26 also has a notch here. The notch is formed in the transverse plane direction of the resectoscope rod 12. The notch extends longitudinally through the entire length of the guide member 26 in a manner not shown here.

[0052] Figure 8A schematic side cross-sectional view of the distal end of an electrode system 44 of the present invention is shown, which includes an insulating insert 18 with a guide 26 (shown in dashed lines) for a support arm 22 of an electrode instrument 16 and a corresponding electrode instrument 16. The electrode system 44 is designed for single use and can be disposed of after use during a medical surgical operation. Alternatively, it is also conceivable to design an electrode system 44 for multiple uses. The insulating insert 18 in the electrode system 44 simplifies the installation of the electrode system on the resectoscope rod 12, because the insulating insert 18, unlike the sensitive electrode instrument 16, can be grasped during installation without the risk of bending. The insulating insert 18 can include a locking mechanism or other fixing mechanism not shown here for fixing, such as the fixing mechanism described in DE102019102841.8. The guide 26 is designed in this case to completely surround the respective support arm 22.

[0053] Although the present invention has been described in detail in conjunction with an embodiment, it is obvious to a skilled person that the present invention is not limited to the embodiment, but can be modified in such a way that some features can be omitted or other forms of combination of the envisaged individual features can be implemented without departing from the scope of protection of the attached claims. All combinations of the envisaged individual features are included herein.

Claims

1. A resectoscope (10) for endoscopic surgery, the resectoscope (10) having a tubular shaft (12) and a handle (14), wherein: The rod (12) includes an electrode device (16) arranged in a longitudinally movable manner and an electrically insulating insulating insert (18) at the distal end of the rod, wherein the electrode device (16) has two elongated support arms and an electrode (24) capable of receiving high-frequency current in the distal end of the electrode device, the support arms forming the rod portion (20) of the electrode device (16), characterized in that the insulating insert (18) has two guide members (26), each of which is used to hold a support arm (22), wherein the support arms (22) can be arranged in the guide members (26) in a longitudinally movable manner, and the guide members (26) are arranged on the inner wall (28) of the insulating insert (18).

2. The resectoscope (10) according to claim 1, characterized in that: The distance between the distal end of the rod (12) and the guides (26) is less than 1 cm.

3. The resectoscope (10) according to claim 1, characterized in that: The longitudinal axes (LF) of the guide elements (26) each extend parallel to the longitudinal axis (LS) of the rod (12).

4. The resectoscope (10) according to claim 1, characterized in that: These guide members (26) surround the corresponding support arms (22) over more than 90° of their circumference.

5. The resectoscope (10) according to claim 1, characterized in that: These guide members (26) surround the corresponding support arms (22) over more than 240° of their circumference.

6. The resectoscope (10) according to claim 1, characterized in that: The electrode (24) is a ring electrode.

7. The resectoscope (10) according to claim 6, characterized in that: The guide elements (26) surround the respective support arm (22) over a 360° range of their circumference.

8. An electrode system (44) for use in an electroresectoscope (10) for endoscopic surgery, characterized in that: The electrode system comprises an electrode instrument (16) and an electrically insulating insulating insert (18), wherein the electrode instrument (16) has two elongated supporting arms and an electrode (24) capable of being acted upon by high-frequency current in the distal end of the electrode instrument, wherein the supporting arms form a rod (20) of the electrode instrument (16), wherein the rod (20) has two supporting arms (22), and wherein the insulating insert (18) has two guide members (26) for respectively holding one supporting arm (22) of the electrode instrument (16), wherein the supporting arms (22) can be longitudinally movably arranged in the guide members (26), and wherein the guide members (26) are arranged on the inner wall (28) of the insulating insert (18).

9. The electrode system (44) according to claim 8, characterized in that These guide elements (26) surround the corresponding support arms (22) over more than 240° of their circumference.

10. The electrode system (44) according to claim 9, characterized in that The guide elements (26) surround the respective support arm (22) over a 360° range of their circumference.

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