referring now in greater detail to the drawings , fig1 illustrates an oblong instrument 1 which in the present case might be a fiber or glass fiber for transmitting light emitted by a laser . the oblong instrument 1 is designed and arranged to be introduced into a working channel 2 . the working channel 2 in particular is built by a flexible endoscope , e . g . a ureterorenoscope . such working channel 2 is arranged parallel to an optical main channel of the endoscope . in order to provide the possibility to introduce instrument 1 into the working channel 2 , the distal end region 3 of instrument 1 is covered , jacketed or housed in the flexible sleeve 4 or flexible tube , wherein the distal end region of the flexible sleeve 4 protrudes from the distal end region 3 of instrument 1 . the proximal end region 6 of the flexible sleeve 4 is fixed at instrument 1 or pressed against instrument 1 which is indicated by arrows in fig1 . in case of the flexible sleeve 4 having a sufficient sheer stiffness or longitudinal stiffness , the fixation of the flexible sleeve at its proximal end region 6 guarantees that the distance the distal end region 5 protrudes from the distal end region 3 of instrument 1 does not vary . fig2 shows the flexible sleeve 4 when introducing the flexible sleeve 4 with an instrument 1 located therein into a curved region of the working channel 2 . in such curved region , there is the danger of “ shaving ”, cutting or abrading the limiting wall 8 of the working channel 2 by edges of the distal end region 3 of instrument 1 which might cause damages of working channel 2 . the flexible sleeve 4 provides a lateral cover for the distal end region 3 of instrument 1 . additionally the distal end region 3 is guided by the protruding distal end region 5 of flexible sleeve through the curved region of the working channel . the limiting wall 8 of working channel 2 deflects the flexible protruding distal end region 5 of flexible sleeve 4 when advancing instrument 1 by pushing the flexible sleeve 4 . the flexibility of the distal end region 5 of flexible sleeve 4 which is larger than the flexibility of the fiber or instrument 1 avoids damages of the wall 8 . furthermore , damages are avoided due to the fact that the outer diameter of the flexible sleeve 4 better approximates the inner diameter of working channel 2 than the outer diameter of instrument 1 . additionally , the material of the flexible sleeve 4 might be chosen such that the friction coefficient between the flexible sleeve 4 and the limiting wall 8 is decreased . on the other hand damages of the wall 8 might be avoided by providing a front edge 9 of the flexible sleeve 4 with a curved contour which is not possible for most instruments or fibers or might only be manufactured at increased costs . fig3 shows an instrument 1 which is completely introduced into the working channel 2 wherein the proximal end region 3 protrudes from the proximal end region 10 of the working channel 2 . the proximal end region 3 contacts a renal calculus 11 . in case of instrument 1 being a fiber for light emitted by a laser , the renal calculus 11 might be fragmented by a pulse of the laser which is transferred and delivered by the fiber . the protective cover 4 is pulled back relative to the instrument 1 . such pulling back might be done by the physician by manually pulling the proximal end region 6 . however , it is also possible to use an automated device for such causing such movement . the protective sleeve 4 is pulled back relative to the instrument 1 as far as necessary for freeing the distal end 3 such that the distal end 3 is located outside the flexible sleeve 4 . the distance the flexible sleeve 4 is pulled back might depend on the design and function of instrument 1 . asides from the configuration shown in fig3 , it might be possible that the two distal end regions 3 and 5 are located in a common plane . it is also possible that the distal end region 3 of instrument 1 is located slightly inside the flexible sleeve 4 adjacent to the distal tip of the flexible sleeve 4 . the step of pulling back the flexible sleeve 4 is performed after having completely inserted instrument 1 into working channel 2 . in such state instrument 1 extends from the proximal end region to the distal end region of the flexible sleeve 4 . the extension of the flexible sleeve 4 in axial direction is longer than that of the working channel 2 . such relation of the lengths guarantees that the proximal end region 6 of flexible sleeve 4 protrudes from the proximal end region of the working channel 2 after completion of the insertion of instrument 1 . fig4 shows a similar arrangement than that of fig3 . however , according to fig4 , flexible sleeve 4 is completely removed and pulled back from the working channel so that only instrument 1 is located inside the working channel . for such embodiment the length of instrument 1 doubles or is larger than the double of the length of the flexible sleeve 4 . the flexible sleeve 4 might have a length of approximately 70 cm . one typical fiber building an instrument 1 might have a length of approximately 3 m . according to one embodiment of the invention , the working channel 2 is a working channel of a flexible ureterorenoscope of the company karl storz sold under the trademark flex - x . the working channel 2 of the endoscope preferably comprises an inner diameter of approximately 1 . 1 mm . in such case the instrument 1 might be embodied in a glass fiber for transmitting energy emitted by a laser . such glass fiber is sold by the applicant under the trademark flexifib and comprises an outer diameter of 0 . 43 mm . the flexible sleeve might be made of ptfe and might have an inner diameter of approximately 0 . 7 mm and an outer diameter of approximately 0 . 9 mm . accordingly , the flexible sleeve 4 might comprises a wall thickness of 0 . 1 mm . the proximal end region of the flexible sleeve is linked with a touhy borst adapter which is sized such that it might be reversibly crimped against the outer diameter of the glass fiber without damaging the glass fiber . the glass fiber is introduced into the flexible sleeve until the glass fiber protrudes approximately 3 to 5 mm from the distal end region 3 . in such arrangement the touhy borst adapter is crimped with the glass fiber . with such fixation the flexible sleeve with the glass fiber embedded therein might be introduced into the working channel 2 of the ureterorenoscope without damaging the limiting wall of working channel 2 by the glass fiber also in cases where the ureterorenoscope is extremely curved . when the distal end region 3 of the glass fiber has passed through the distal end region 10 of the working channel 2 , the touhy borst adapter is released and the flexible sleeve 4 is removed and pulled out of the working channel 2 . the position of the glass fiber relative to the endoscope is fixed when removing the flexible sleeve 4 . according to another embodiment of the invention , the flexible sleeve might have a length of approximately 1 m . the outer diameter of the flexible sleeve might be 0 . 9 mm which is appropriate for 3 . 6 fr working channels . the clearance might be 0 . 6 mm for commonly used laser fibers . fig5 shows a curved region of a working channel 2 with a flexible sleeve 4 with an embedded instrument 1 located therein . according to the embodiment shown in fig5 , the distal end 5 is slanted or cut with an angle which differs from a direction perpendicular to the longitudinal axis of the flexible sleeve 4 . the distal end region 5 might be cut in a straight or curved plane . the end region 5 might have a front face 12 with an elliptical outer and inner geometry . the sloped design of the distal end region 3 has two effects shown in fig5 and fig6 : according to fig5 , the sloped end region 3 might result in a front face 12 which anticipates the curvature of the working channel 2 such that the front face contacts the working channel at a small angle and maybe with an increased contact surface . according to fig6 , for a different orientation of the flexible sleeve it might be helpful that due to the sloped distal end region 5 of the flexible sleeve 4 the cross - section of the distal end region decreases continuously to 0 in the direction of the distal tip 13 of the flexible sleeve 4 . this means that the distal tip of the end region might be easily deflected such that the distal end region 5 easily assimilates to the curvature of the working channel 2 . the elasticity of the flexible sleeve 4 might additionally be reduced by providing at least the distal end region 5 with bores , slots and the like . the distal end region 3 of the instrument 1 is preferably located with a small distance from the slanted end region 5 where the full cross section is available in order to provide fill coverage of any edges of the end region 3 . fig1 , 5 and 6 show the endoscope in a first operational state whereas fig4 shows the endoscope in a second operational state and fig3 shows the endoscope in a third operational state . many variations and modifications may be made to the preferred embodiments of the invention without departing substantially from the spirit and principles of the invention . all such modifications and variations are intended to be included herein within the scope of the present invention , as defined by the following claims .
the present invention relates to an endoscope , in particular an ureterorenoscope . the endoscope comprises a lumen for insertion of a light and energy transmitting fiber . according to the invention during insertion of the fiber into a working channel of the endoscope the sharp edges of the fiber are protected by a flexible sleeve in order to avoid damages of a wall limiting the working channel . prior to using the fiber for transmitting energy emitted by a laser the flexible sleeve is completely removed from the working channel in order to free a lumen that might be used for additional instruments or delivery of a fluid . furthermore the stiffness of the endoscope is reduced by removing the flexible sleeve .