DE102017005063A1 - Medical instrument for extracting urinary stones from a ureter - Google Patents

Abstract

The invention relates to an instrument for fixation and extraction of urinary stones from the ureter. This consists of a lubricious surface cross-section variable expansion balloon integrated in a stone fixation instrument which can be enlarged to the required size until the ureteral mucosa is lifted off the urinary stone and thereby providing injury-free and traumatizing-free removal of the urinary stone is possible.

Description

The present invention relates to a medical instrument for the extraction of urinary stones from a ureter, comprising a manipulation handle, a channel element and a catch head, the latter having a per se known Steinfangelement and according to the invention comprising a Aufweitungsballon, which is arranged behind or on the stone catch element annular.

The spirit:

• - Dilation, namely an expansion of the ureter, and avoiding postponement of the ureteral mucosa in the extraction of a ureteral stone.
• - Avoidance of a so-called "girl catcher principle", namely by train in the interior of a hollow organ generated contraction, as in a ureter, in the extraction of urethra stone.
• - Forming a lubricious envelope of the foreign body / urinary stone to be removed to avoid the delay of the mucous membrane.

Prior art: First, according to the publication DE 39 13 935 A1 a catheter for the extraction of ureteral stones is known, which, starting from the tip of the catheter, via a drawstring wraps a net over the urinary stone, in order subsequently to extract it as a whole.

Second, an instrument is known which grasps the urinary stone by means of a forceps-shaped instrument attached to the tip of the catheter to remove it as a whole.

In a third known instrument and method for the extraction of large ureteral stones their disintegration is performed and the multiple disintegrates extracted. The disintegrates are then fixed and removed individually by repeated passage of the ureter through the instrument.

Disadvantage of the first and second mentioned prior art is that it is not possible to perform a complete removal via in Toto extraction due to a postponement of the mucous membrane of the ureter in larger stones. The system-inherent "girl catcher principle" further reduces the hollow organ cross-section so that increased traction leads only to further constriction of the passable hollow organ lumen of the ureter. It must therefore be done to avoid disintegration of the large stone. The disintegrates can be carried back to the renal pelvis via flushing flow. Here, a refurbishment succeeds only via flexible URS. The disintegration leads to a clear traumatization of the mucous membrane of the ureter. The disintegrates usually have to be recovered individually in a time-consuming and thus expensive procedure.

Disadvantages of the third-mentioned prior art is:

In the extraction of disintegrates and smaller stones at least a traumatization of the mucosa is provoked by friction by their rough surfaces after their fixation by forceps or Stiffangkörbchen. In addition, this process is very time-consuming and therefore expensive.

The object of the invention is to propose an instrument for the extraction of ureteral stones from the urethra, with which the disadvantages mentioned are avoided, expressis verbis: to eliminate the disadvantages mentioned by its application.

It is the object of the invention to avoid the generated by friction in combination with train resp. Deferment of the mucous membrane and thus to avoid a significant narrowing of the cross section of the hollow organ to be passed.

Further, it is Aufgbe the invention to reduce the time and thus the costs of the procedure while avoiding Traumatiseirung the ureteral mucosa

This object is achieved by an instrument for fixation and extraction of urinary stones from the ureter according to claim 1.

The solution consists of a cross-sectional variable expansion balloon with a lubricious surface integrated into the stone fixation instrument, which can be enlarged in view of the required size until the ureteral mucosa is lifted from the urinary stone and thereby eliminating injury-free and traumatizing-free removal of the urinary stone Harnsteins is possible.

Advantageous embodiments of the invention are specified in the subclaims 2 to 8.

Advantages of the invention.

By shielding the most strongly in contact with the stone surface mucous membrane a significantly higher lubricity is achieved with less tension. By prolonged bougienage of the mucous membrane can also be achieved a larger Passagequeschnitt.

The expected effects also consist of much shorter operating times and significantly lower iatrogenic ?? Traumatization through the procedure. Shorter hospitalization times and fewer follow-up procedures are the goal to be achieved.

Advantageous embodiments of the present invention will be explained in more detail with reference to drawing figures without thereby limiting the scope of the invention.

Show it:

• 1A eine Gesamt- Darstellung des erfindungsgemäßen Instruments, bestehend aus einem Kanalelement, einer Handhabe und einem Fangkopf.
• 1B einen vergrößerten Teilausschnitt IB, zeigend den Fangkopf nach 1A.
• 2A eine Ausschnitts- Darstellung des Kanalelements mit Fangkopf FKI, zeigend das Einbringen des Fangkopfes in den Harnleiter und den zu extrahierenden Harnstein etwa im Maßstab 1.1.
• 2B eine vergrößerte Detaildarstellung aus 2A, etwa im Maßstab 3:1.
• 3 A das Einfangen des Harnsteins durch das Fangkörbchen.
• 3 B das Ballonelement nach 3A vor seiner Aufweitung.
• 4 das Aufweiten des Harnleiters durch das Ballonelement und die Extraktion des Harnsteins

Beispiel II: 5A bis 6 eine zweite Ausführung der Erfindung mit einem Fangkopf FKII, beinhaltend ein ein-seitig eingestülptes längliches Ballonelement, welches auf dem Ende des Kanalelements befestigt ist, dabei im Einzelnn:

• 5A das längliche Ballonelement in seiner Abrollphase vor dem Einbau.
• 5B das einseitig eingestülpte und einbaubereite Ballonelement.
• 5C die längliche Bougierung des Harnleitersden Fangkopf FKII in der Einfang und Extraktion-Situation des Harnsteins, wobei das Ballonelement eine Pufferfunktion zum Harnstein einnimmt.
• 6 eine Situation der Extraktion bei welcher das Ballonelement den Harnstein partiell übergreift.

Beispiel III: 7A bis 13 zeigen eine dritte Ausführung der Erfindung mit einem Fangkopf FK III, beinhaltend ein beidseitig eingestülptes Ballon-element, welches auf dem Ende des Kanalelements befestigt ist. Dabei zeigen im Einzelnen:

• 7A das beidseitig eingestülpte Ballonelement vor dem Einbau.
• 7B den fertig bestückten Fangkopf FKIII , eingeführt in den Harnleiter.
• 8 eine vergrößerte Darstellung des Fangkopfes FKIII nach 7B, wobei das das Fangkörbchen noch zusammengefaltet in einer Führungshülse verschieblich in noch eingezogener Situation gelagert ist.
• 9 das Einfangen des Harnsteins in der ersten Phase, wobei das Fangkörchenaus der Führungshülse ausgefahren ist.
• 10 das Herausfahren der Führungshülse und damit die engere Einfangung des Harnsteins durch das Fangkörbchen in Phase zwei.
• 11 das Heranführen des Fangkopfes FKIII an den eingefangenen Harnstein.
• 12 eine schematische und vergrößerte Darstellung im Bereich XII der 11. im noch zusammengelegten Zustand des Ballonelements.
• 13 die durch das Ballonelement aufgeweitete Situation welche zur Abhebung des Harnsteins von der Harnleiterschleimwand führt und damit dessen berührungsfreie Extraktion ermöglicht.

Beispiel IV: 14A bis 22 eine vierte Ausführung der Erfindung mit einem Fangkopf FK IV, beinhaltend ein beidseitig eingestülptes Ballonelement, welches auf der Führungshülse des Fangkörbchens befestigt ist.
Dabei zeigen im Einzelnen:

• 14A den in den Harnleiter eingeführten Fangkopf FK IV,wobei das Fangkörbchen noch eingezogen und zusammengefaltet ist und das Ballonelement ebenfalls noch zusammengefaltet ist.
• 14 das zusmmengefaltete Ballonelement im Schnitt.
• 15 eine vergrößerte Detaildarstellung aus dem Bereich VX der 14A.
• 16 das Einfangen des Harnsteins durch das Körbchen, wobei sowohl die Mandrinenhülse als auch der auf ihr befindliche Ballonschaft, auf welchem sich das nochnoch das zusammengefaltete Ballonelemen befindet, ausgefahren sind.
• 17 eine vergrößerte Darstellung des Details XVII der 16.
• 18 die Heranbewegung des Ballonelements an den Harnstein bei gleichzeitigem Zusammenziehen des Fangkörbchens um den Harnstein.
• 19 die durch das Ballonelement aufgeweitetet Situation zur erlangten Abhebung der Harnleiterschleimhaut vom Harnstein.
• 20 eine vergrößerte Darstellung des Detailbereichs XX der 19.
• 21 die Extraktion des Harnsteins, bei gleichzeitiger Führungs-Pufferung des Harnsteins durch das Ballonelement.
• 22 die Fortführung der Extraktion des Harnseins, wobei das Ballonelement den Harnstein weiter umfasst und die Abhebung der Schleimhaut, auch von der der aufgeschobenen Schleimhaut, weiter fortgeschritten ist und ein Abgleiten auf dem konischen Rücken des Ballonelements schleimhautschonend stattfindet.

Example I: 1A to 4 a first embodiment of the invention with a catch head FKI comprising a balloon element not inverted on both sides, which is fastened on the end of the channel element. In detail:

• 1A an overall view of the instrument according to the invention, consisting of a channel element, a handle and a catch head.
• 1B an enlarged partial section IB , pointing the catch head after 1A ,
• 2A a detail of the channel element with catch head FKI , showing the introduction of the catch head in the ureter and the urinary stone to be extracted approximately in scale 1.1.
• 2 B an enlarged detail 2A , about in the scale 3: 1.
• 3 A trapping the urinary stone through the collecting basket.
• 3 B the balloon element after 3A before its expansion.
• 4 the dilation of the ureter by the balloon element and the extraction of the urinary stone

Example II: 5A to 6 a second embodiment of the invention with a catch head FKII comprising an elongated balloon element which is inverted on one side and which is fastened on the end of the channel element, wherein in the detail:

• 5A the elongated balloon element in its unrolling phase prior to installation.
• 5B the one-sided inverted and einbaubereite balloon element.
• 5C the elongated bougienage of the ureter is the catch head FKII in the capture and extraction situation of the urinary stone, wherein the balloon element occupies a buffering function to the urinary stone.
• 6 a situation of extraction in which the balloon element partially overlaps the urinary stone.

Example III: 7A to 13 show a third embodiment of the invention with a catch head FK III including a bilaterally inverted balloon element mounted on the end of the channel member. In detail:

• 7A the double-sided inverted balloon element before installation.
• 7B the ready equipped catch head FKIII, introduced into the ureter.
• 8th an enlarged view of the catch head FKIII after 7B , Wherein the collecting basket is still stored folded in a guide sleeve slidably stored in still retracted situation.
• 9 the capture of the urinary stone in the first phase, wherein the Fangkörchenausfahren from the guide sleeve.
• 10 the retraction of the guide sleeve and thus the narrower capture of the urinary stone by the collecting basket in phase two.
• 11 the introduction of the catch head FKIII to the captured urinary stone.
• 12 a schematic and enlarged view in the area XII of 11 , in the still folded state of the balloon element.
• 13 the dilated by the balloon element situation which leads to the lifting of the urinary stone from the ureter mucus wall and thus enables its non-contact extraction.

Example IV: 14A to 22 A fourth embodiment of the invention with a catch head FK IV comprising a balloon element inverted on both sides, which is fastened on the guide sleeve of the collecting basket.
In detail:

• 14A introduced into the ureter catch head FK IV, wherein the collecting basket is still retracted and folded and the balloon element is also still folded.
• 14 the folded balloon element in section.
• 15 an enlarged detail of the area VX of 14A ,
• 16 the trapping of the urinary stone through the basket, wherein both the Mandrinenhülse and the ballon shaft located on her, on which the nochnoch the folded balloon elements is, are extended.
• 17 an enlarged view of detail XVII of the 16 ,
• 18 the movement of the balloon element towards the urinary stone with simultaneous contraction of the collecting basket around the urinary stone.
• 19 the situation widened by the balloon element leads to the withdrawal of the ureteral mucosa from the urinary stone.
• 20 an enlarged view of the detail area XX of 19 ,
• 21 the extraction of urinary stone, while simultaneously guiding buffering of the urinary stone by the balloon element.
• 22 the continuation of the extraction of urine, wherein the balloon element further comprises the urinary stone and the lifting of the mucous membrane, also of the deferred mucosa, has progressed further and slipping on the conical back of the balloon element takes place mucosal gentle.

The following is a detailed description of four execution examples:

The 1A to 4 show the first embodiment of the instrument according to the invention 1 consisting of a flexurally elastic channel element 1a , a handle 6 and a catch head FKI in which a cylindrical expansion balloon 7 with its two un-inverted ends 7a , 7b is arranged. Here is the channel element 1a double-walled in the form of an outer tube 1b and an inner tube 1d formed, with a gap between these two hoses 1c for the hydraulic pressure medium 9 for insertion and expansion of the balloon 7 is trained. This balloon 7 is in its front area Z1 in the end cap 18 of the channel element 1a and its rear area Z2 on the outer tube 1b fixed, as by an opening 1f the hydraulic pressure medium 9 in the balloon 7 can occur and thus, according to 4 , the balloon 7 causes dilatation and consequently the ureter 3 also dilated (dilation) to the mucous membrane 8th respectively. whose through the stone 5 advanced mucosa 8a from the stone 5 lifted ( 15 ). Here is the entire area of the ureter 3 introduced channel element 1a as well as the expansion balloon 7 on their outsides with a radiopaque lubricant 14 provided to a trauma-free extraction of the stone 5 from the ureter 3 sure.

In this context, the area facing the patient or the area of the instrument facing away from the user for the entire application applies as positional definition for "front", while for "behind" the area applies to the instrument, which faces the user, resp. facing away from the patient.

In the channel element 1a is the actuator 4 consisting of four mandrines 16 and their ummabtelung 17 , which by the rear of the instrument arranged handle 6 is controlled, such that it is a catch element 2 B controls which is located in the front area of the instrument. This actuator 4 consists of four mandrines 16 , which are twisted at its front end and thus a mesh hose 2a form and with their front ends in an end cap 2 united to each other. This will be when extending the twisted area 2a the mandrine 16 This automatically to a collecting basket 2 B unfolds the stone 5 is able to capture ( 3A and 4 ).

The function of this version of the medical instrument 1 or his catch head FKI is as follows: To become the channel element 1a and the expansion balloon 7 outside with radiopaque lubricant 14 Mistake ( 1 A and 1B ). Subsequently, the catch head FKI in the ureter 3 until just before the stone 5 introduced (Fig, 2A and 2 B Now the twisted net tube end will be 2a about the handle 6 extended and on the stone 5 past. This unfolds the net tube end 2a and expand to the catcher basket 2 B where it is the stone 5 captivating ( 3A ). Here is the balloon 7 not yet expanded ( 3B ).

Would you already now about the actuator 4 the stone 5 Extract, then the so-called girl catcher principle would be effective, since the front of the stone 5 deferred mucous membrane 8a its extraction is blocked and consequently the one behind the stone 5 lying area of the ureter 3 is stretched in length. At the same time, a contraction would occur 30 of the ureter 3 what, to its demolition 31 would lead, as in 3A shown in dashed lines.

The invention solves this problem by a widening balloon 7 , In the process, the balloon first becomes 7 over the opening 1f at the channel element 1a by introducing hydraulic pressure medium 9 expands, taking a dilation of the ureter 3 to a degree takes place until the mucous membrane 8th of the ureter 3 , or the deferred mucosa 8a a clear withdrawal 15 from the stone 5 Experienced ( 4 ). The stone 5 can now be easily extracted. At the same time the mucous membrane slides 8th of the ureter 3 on the with lubricant 14 provided outside of the balloon 7 injury free ( 4 ). The stone can do that 5 as close as possible to the end cap 18 be used to a short buffer zone 11 between stone 5 and end cap 18 and thus to achieve an optimally safe control procedure of the extraction.

The 5A to 6 show a second embodiment, wherein the structure of the medical instrument in the field of stone catcher, such as actuator 4 and catching baskets 2 B that the 1 but a catch head FKII with a radially and axially acting expansion balloon 10 having.

It is at the front end of the elastic channel element 1a through an end cap 18 completed, on which the front inverted hemispherical part 10b of the balloon 10 with his area X on the end cap 18 is attached liquid-tight. The rear cylindrical part 10c of the balloon 10 on the other hand, similar to the first example, on the outer tube 1b of the sewer segment 1a un-inverted and attached liquid-tight. This will allow the balloon 10 expand both radially and axially.

In 5A is the first manufacturing stage of the balloon 10 shown, which initially in the right part 10c cylindrical and forming a collar-shaped passage opening 10d in the left part 10c is formed hemispherical. Subsequently, the hemispherical area 10b . X liquid-tight on the end cap 18 attached and subsequently the cylindrical part 10c over the outer tube 1b of the channel element 1a unrolled ( Y ) and with its rear end thus formed Z liquid-tight on the channel element 1a attached ( 5C ). The expansion balloon thus formed 10 to 5B can thus both axially, forming a buffer 10a in the buffer zone 11 with the stone 5 , as well as to form a Abgleitkonus 12 for the ureter 3 , expand. The stone can do that 5 in the buffer zone 11 to the buffer 10a of the balloon 10 be pulled, whereby the control of the extraction is optimized. The sliding cone 12 is in its outer area with a radiopaque lubricant 14 provided, so that an injury-free sliding of the ureter 3 during the extraction of the stone 5 given is.

The 6 shows a situation where the balloon 10 axially further expanded and thus the stone 5 , forming a stone 5 encompassing pot-like extension 10 leader surrounds.

The 7A to 13 show a third embodiment of the invention with a catch head FK III including a balloon element inverted on both sides 13 which is on the end of a rigid channel element 1e is attached. The 7A shows the balloon element 13 which is made from a blank with the total length L1 is made. It will be the ends of the lengths L2 and L3 inverted, such that the base balloon part 13a , the first invagination 13b and the second invagination 13c arise. The latter will work with your areas X and Z on the front end of the rigid channel element 1e attached liquid-tight ( 7B ).

The ready equipped Fankkopf FKII is in enlarged scale in 8th reproduced. There is the catching basket 2 B as shown before and still shown folded. Here is clearly the coiled groove 22 for the supply of hydraulic medium 9 for the expansion of the balloon 13 (Fig, 13) shown. First, however, is the entire process for extracting the stone 5 in which the corresponding reference numerals denote the same parts as before and these are not all repeated in detail 9 is the extension of the basket 2 B and the trapping of the stone 15 shown. In 10 is the sheath 17 for the simplified illustrated bundle of mandrels 16 spent in advanced position to the stone 5 thus narrower and then close to the rigid channel element 1e to be used as in 11 represented and enlarged in 12 shown.

Well done after 13 the introduction of the hydraulic pressure medium 9 which over the opening 1f in the balloon 13 enters and this, here asymmetrically, expands to the mucous membrane 8th of the ureter 3 a withdrawal on all sides 15 from the stone 5 has experienced and causing the extraction of the stone 5 can be done. Again, similar to in 5c and 6 described, the mucous membrane-gentle sliding of the mucous membrane 8th on the with radiopaque lubricant 14 provided outer surface of the balloon 13 ,

The 14A to Fig. 22 show a fourth embodiment of the invention with a catching head FK IV , as before in the example FK III , the folded basket 2 B in the sheath 17 the mandrine 2 B is arranged and, in contrast to before, the double-inverted balloon element 19 on this sheath 17 is angeornet, so that both together, collecting baskets 2 B and expansion balloon 19 , in the balloon and in the basket channel 1g of the rigid channel element 1e are arranged.

To 14 A It is also a big urinary stone here 15 to extract, here again an obstacle in the form of deferred mucosa 8a which does not allow the conventional extraction.

The 14 B and 15 show the balloon 19 with his two invaginations 19b and 19c , wherein its outer main part 19a remains undripped and initially in the balloon and basket channel 1g comes to the plant.

The extraction of urinary stone 5 takes place here in the following steps: After 16 becomes the catching basket 2 B extended and catches the stone 5 one. This was the on the collecting basket guide sleeve 21 located, still folded expansion balloon 19 , taken away ( 17 ), now through through the mandrels bundle 16 the collecting basket 2 B retracted while the balloon 19 remains in its position. This will be the stone 5 closer to the rigid channel element 1e used ( 18 ). Now according to 19 and 20 the hydraulic pressure medium 9 in the balloon 19 introduced, the balloon 19 expand until it is at 15 for all-round lifting of the mucous membrane 8th from the stone 5 came and the extraction can take place.

In 21 a situation is shown where the balloon 19 axially asymmetric expanded. In 22 a situation is shown in which the expanded balloon 19 a receiving chalice 40 for the stone 5 forms.

The Erfndung includes all, also not shown balloon expansion options. Thus, in all cases, the expansion balloons are suitable for extraction, even large urinary stones 5 , on her, with radiopaque lubricant 14 provided outer sides, an injury-free sliding of the mucous membrane 8th respectively. of the ureter 3 to enable.

LIST OF REFERENCE NUMBERS

FK I

Fangkopf, first example ( 1A to 4 )

FK II

Fang head, second example ( 5A to 6 )

FK III

Fangkopf, third example ( 7A to 13 )

FK IV

Fangkopf, fourth example ( 14A to 22 )

1

Instrument for the extraction of ureteral stones ( 1 )

1a

elastic channel element (double hose 1 to 6 )

1b

outer tube

1c

Gap for the balloon pressure medium

1d

inner tube

1e

rigid channel element ( 7 to 22 )

1f

Inlet opening for the pressure medium 9 in the balloon.

1g

Balloon and basket channel ( 15 )

2

End cap to catch element 2 B respectively. Bundling the Mandrine 16 ,

2a

made of mandrines 16 formed and twisted net tube end ( 1B )

2 B

Catch element / catch basket

3

ureter

4

Actuator here consisting of four mandrels 16 and their sheathing 17 (All examples))

5

urinary calculus

6

handle

7

Expansion balloon on elastic channel end 1a mounted, not inverted on both sides (in the example FK I ).

7a

unopposed end

7b

unopposed end

8th

Ureteral mucosa

8a

deferred ureteral mucosa

9

Hydraulic pressure medium for balloon expansion.

10

Expansion balloon mounted on the Elasian channel end and on the fixed channel end head, inverted on one side. (in the example FK II )

10a

Buffer on the balloon 10

10b

hemispherical part of 10

10c

cylindre part of 10

10d

constriction

10e

pot-like extension ( 6 )

11

buffer zone 2 B / 5 (in 5c )

12

Sliding cone for mucous membrane (in 5c and 6 )

13

Expansion balloon on the rigid channel end 1e mounted, inverted on both sides (in the example FK III )

13a

Based balloon portion

13b

first invagination

13c

second invagination

14

Radiopaque lubricant

15

Lifting of the mucous membrane 8th / Stone 5

16

Mandrine

17

Sheathing the Mandrine 16 , or basket elements 2 B ( 15 )

18

End cap of channel element 1a

19

Expansion balloon on the collecting basket guide sleeve 21 mounted, inverted on both sides (in the example FK IV )

19a

Based balloon portion

19b

first invagination

19c

second invagination

20

---

21

Catch Guide Sleeve (in 15 to 22 )

22

Coiled groove for the print medium 9

30

Contraction (girl catching)

31

Outline of the ureter 3

Z1

front mounting area for balloon 7

Z2

rear mounting area for balloon 7

X

front mounting area for balloon 10 . 13 . 19

Y

Unrolling of the balloon skin ( 5A )

Z

rear mounting area for balloon 10,13,19

L1

Overall length of balloon element blank 13 ( 7A )

L2

Length of the front invagination of balloon element 13 ( 7A )

L3

Length of the posterior invagination of balloon element 13 ( 7A ).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3913935 A1 [0002]

Claims (12)

Medical instrument for capturing, fixing and extracting urinary stones (5) from a ureter (3), comprising a channel element (1a) which has a catch element (2, 2b) at its front end region which is suitable for insertion into the ureter (3) still takes the form of a twisted mesh hose (2a) and then via an adjusting element (4) in the form of a collecting basket (2b) is spread, which is able to capture the urinary stone (5) catching, wherein the adjusting element (4) from a handle (6) at the rear end of the channel element (1a) is manipulatable, and an expansion balloon (7, 10, 13, 19) which is arranged at the front end portion of the channel element (1a) around the insertion end and which after capturing the Urinary stone (5) with the collecting basket (2b) via the introduction of hydraulic pressure medium (9) is expandable such that the ureter (3) in the area of the urinary stone (5) is widened so far that the mucous membrane (8) of the urinary (3) stands out from the urinary stone (5) (15) (All examples FK I to IV). Medical instrument after Claim 1 wherein the expansion balloon (10, 13, 19) is further adapted not only to expand radially but also to expand asymmetrically in the axial direction beyond the front end of the channel member (1a) in the direction of the catching basket (2b) to form a buffer (11) to the urinary stone (5) (Examples FK II, III, IV). Medical instrument after Claim 1 in which the expansion balloon (7) is arranged unextended around the insertion end of the channel element (1a) both with its rear end and with its front end (example FK I, 1 to 4 ). Medical instrument after Claim 1 or 2 , wherein the expansion balloon (10) with its rear end unopposed on the elastic end region of the channel element (1 a) and with its front end invaginated on a rigid end cap (18) of the channel element (1 a) is arranged. (Example FK II, 5A to 6 ) Medical instrument after Claim 1 or 2 , wherein the expansion balloon (13) on the rigid channel end (1e) is arranged inverted on both sides (Example FK III, 7A to 13 ). Medical instrument after Claim 1 or 2 , wherein the expansion balloon (19) arranged on a collecting basket guide sleeve (21) arranged on both sides (X, Y). (Example FK IV, 14 A to 22 ). Medical instrument according to one of the preceding claims, wherein the expansion balloon (10) is arranged to expand in the radial direction to varying degrees to form a ring cone (12) for the gentle sliding of the mucosa (8) of the ureter (3). 5C ). Medical instrument according to one of the preceding claims, wherein the expansion balloon (10, 13, 19) is arranged to expand in radial and in two opposite axial directions ( 5C . 6 ). Medical instrument according to one of the preceding claims, wherein the expansion balloon (10, 13, 19) is adapted to extend axially and radially partially surrounding the urinary stone (5) (Example FK II, 6 and example FK IV. 22 ). A medical instrument according to any one of the preceding claims, wherein a radiopaque lubricant (14) is applied to the surface of the channel member (1a, 1e) and to the surface of the expansion balloon (7, 10, 13, 19). Medical instrument according to one of the preceding claims, wherein the hydraulic pressure means (9) in the channel element (1a) is a radiopaque contrast agent (all examples). Medical instrument according to one of the preceding claims, wherein the adjusting element (4) consists of several mandrels (16) which at their front end the catch element (2, 2a, 2b) and which in a casing (17) are axially movable (all Examples FK I to FK IV).

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