FIELD

The invention relates to a resectoscope and an electrode assembly therefor.

BACKGROUND

Resectoscopes are used in minimally invasive surgical procedures, especially in urology, but also for example in gynecology. At their distal end, they have one or more exposed electrodes for working on tissue. The electrodes can be monopolar or bipolar electrodes. However, it is also possible that the electrode is configured as a free end of a laser fiber.

Resectoscopes generally have an elongate shaft tube for inserting into the body of the patient. A likewise elongate optic is arranged in this shaft tube, and an objective lens is provided at the distal end of the optic. At the other end of the optic, an eyepiece can be provided through which the operator is able to view the operating area in front of the objective lens.

A longitudinally displaceable electrode assembly, with an electrode at the distal end, is likewise arranged in the shaft tube. The electrode assembly can be moved between a retracted state, in which the electrode is arranged inside the shaft tube and directly in front of the objective lens, and a deployed state, in which the electrode protrudes freely from the shaft tube.

In the deployed state, the electrode is located in the viewing field of the optic. To have a good view of the electrode, the operating region is rinsed with a rinsing liquid, in such a way that a constant pressure prevails in the operating area. At the same time, a suitable arrangement of the delivery and aspiration of rinsing liquid is intended to ensure that the region directly in front of the optic remains as far as possible free of dirt obstructing the view, e.g. caused by blood which has leaked out or floating tissue fragments. A crucial requirement for this is the time that is needed until the viewing field of the optic is once again free after becoming dirty.

In order to achieve a flow around the objective lens suitable for rinsing the viewing field free, the rinsing liquid is at least generally delivered directly via the resectoscope. However, the time needed to rinse the viewing field in front of the optic free after soiling is often unsatisfactorily long.

SUMMARY

The object of the invention is to create a resectoscope and an electrode assembly in which the disadvantages of the prior art no longer arise or only arise to a reduced extent.

This object is achieved by a resectoscope according to the main claim and by an electrode assembly for use in such resectoscope according to another independent claim directed to such electrode assembly. Advantageous developments are the subject matter of the dependent claims.

Accordingly, the invention relates to a resectoscope comprising an elongate shaft tube, an elongate optic arranged therein with an objective lens at the distal end and an electrode assembly, wherein the electrode assembly comprises an electrode arranged at the distal end of the arms of a fork assembly, which are arranged on opposite sides of the objective lens and are brought together in a transition region to an electrode shaft, wherein the electrode assembly can be deployed in the longitudinal direction by a stroke length from a first position, in which the electrode is arranged inside the shaft tube in front of the objective lens, to a second position, in which the arms of the fork assembly protrude from the shaft tube, wherein the length of the arms of the fork assembly is greater than 1.2 times the stroke length.

The invention also relates to an electrode assembly for use in a resectoscope (preferably according to the invention), in which the electrode assembly can be deployed in the longitudinal direction by a stroke length, comprising an electrode arranged at the distal end of the arms of a fork assembly, which are brought together in a transition region to an electrode shaft, wherein the length of the arms of the fork assembly is greater than 1.2 times the stroke length.

The invention is based on the recognition that, at least in electrode assemblies which are known from the prior art and which as in the one according to the invention comprise a fork assembly, a transition region and an electrode shaft, but in which the length of the arms of the fork assembly corresponds substantially to the stroke length, the transition regions regularly cause swirling movements in the flowing rinsing liquid in the region directly in front of the objective lens, which is detrimental to the rinsing free of the viewing field. This is because, with a corresponding length of the arms of the fork assembly, the transition region in the deployed state is located directly adjacent to the objective lens and can then cause the undesired swirling movements in the flowing rinsing liquid in the region directly in front of the objective lens.

Since provision is made, according to the invention, that the length of the arms of the fork assembly is considerably greater, namely at least 20% greater, than the stroke length, this has the effect that the transition region of the electrode assembly, even in the deployed state, is arranged sufficiently far from the objective lens of the optic that the transition region causes no swirling movements, or fewer swirling movements compared to the prior art, rinsing free that delay the in the rinsing liquid of the viewing field.

It is preferable if the length of the arms of the fork assembly is greater than 1.3 times the stroke length, preferably greater than 1.4 times the stroke length, more preferably greater than 1.5 times the stroke length. With a suitable length of the arms of the fork assembly, the interference effect of the transition region on the flow in the region of the objective lens can be further reduced. In order to ensure a sufficient stability of the fork assembly, it is preferable if the length of the arms of the fork assembly does not exceed 1.8 times the stroke length.

The transition region of the two arms of the fork assembly to the electrode shaft can be designed in each case with a reflexed airfoil profile. A reflexed airfoil profile is a flowingly curved transition reminiscent of an S shape and leads tangentially from one arm of the fork assembly tangentially to the electrode shaft substantially without an abrupt change of angle. For better guiding of the electrode assembly in the region of the distal end of the shaft tube, a guide element can be provided on the electrode shaft, adjacent to the transition region, which electrode shaft interacts with the optic in such a way that the electrode shaft is guided along the optic. The guide element can be tubular, for example, such that, particularly in the case of a circular cross section of the optic, it engages completely or at least partially around the latter. In the case of partial engagement, the guide element extends over at least 60% of the circumference of the optic.

The advantages of the invention can be realized in different designs of resectoscopes and with different types of rinsing liquid delivery. In particular, however, the advantages of the invention come to bear if the region between the shaft tube and the optic is configured for rinsing liquid delivery. The rinsing liquid in this case flows along the optic, through the region in which the electrode assembly is also located, and emerges at the distal end of the resectoscope. By virtue of the configuration of the electrode assembly according to the invention, flow effects in the stream of rinsing liquid, which may in particular arise on account of the transition region of the electrode assemblies, are situated sufficiently far from the objective lens of the optic, even in the deployed state, to ensure that these flow effects do not cause any swirling movements, or cause only slight swirling, in the region directly in front of the objective lens.

The shaft tube is preferably double-walled, wherein the region between the walls of the shaft tube is configured for rinsing medium discharge. With a suitable configuration, the rinsing liquid can be delivered and also discharged through the resectoscope, such that no separate rinsing liquid delivery devices or rinsing liquid discharge devices need to be provided in an intervention.

The electrode of the electrode assembly is preferably a bipolar electrode. It is more preferably configured as a loop electrode or a flat vaporization electrode.

The stroke length of the resectoscope is preferably 24 mm. The length of the arms of the fork assembly then preferably measures 30 mm to 28 mm, more preferably 32 mm to 34 mm.

For the explanation of the electrode assembly according to the invention, reference is made to the above observations.

