Abstract:
Placement of a stent having a tethered ferromagnetic bead may be facilitated with a modified pusher having an opening at the distal end of the pusher to receive the tethered ferromagnetic bead. The ferromagnetic bead may be positioned within the bladder whereby a tether connection to a shortened stent ending within the ureter may be used to reduce the likelihood of patient irritation. The bead, tether, and stent assembly may be advanced into the patient as a unit along a conventional guide wire and using a conventional cystoscope.

Description:
RELATED APPLICATIONS 
     This application is a National Stage Application of International Application Number PCT/CA2013/000438, filed May 3, 2013; which claims priority to U.S. provisional patent application Ser. No. 61/649,102, filed May 18, 2012; which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to the field of stent placement, where the stent may be used to keep open body channels. In particular, the invention relates to a stent placement pusher apparatus. 
     BACKGROUND 
     Stents are used to keep open body channels. For example, ureteral stents may provide drainage of urine from the kidneys to the bladder. Similarly, biliary stents may provide drainage of the bile ducts between the liver and gallbladder and between the gallbladder and small intestine. A stent is a flexible, tubular structure that is made from relatively inert materials (for example, silicon, Teflon™, polyethylene, polyurethane, stainless steel, or nickel-titanium alloy). Often a stent may be perforated to provide small drainage holes along its length. Stents may also be shaped to define “hooks” at either end. For example, such hooks may prevent migration of a ureteral stent from the kidney toward the bladder or from the bladder upwards. A shortened ureteral stent has only one hook at the distal or kidney end of the stent. Often, shortened stents are used to reduce irritation caused by the presence of a stent within the lower ureter and within the bladder. With a shortened stent, the stent resides in the ureter, remote from the bladder and the ureteral orifice (i.e. the junction of the ureter and the bladder). 
     Indwelling stents periodically need to be removed or periodically replaced. Conventional stent removal procedures may be complex and may be painful, sometimes requiring general anesthesia. 
     A thin thread may be attached to a shortened stent to extend into the bladder to assist with the removal of the stent. However, such a shortened stent (with thread) requires endoscopic visualization of the threads so that they may be grasped, and the stent may be withdrawn. 
     Although this is a relatively simple procedure, it requires specialized instruments used by an urologist in a sterile setting. Nevertheless, general anesthesia may also be required. 
     An alternative stent removal method is described in WO 99/58083, which employs the use of a tethered bead at the proximal or bladder end of the stent that may be removed with the aid of magnet tipped catheter. 
     SUMMARY 
     The pusher apparatus or pusher attachment apparatus attached to a pusher described herein allow for the insertion of a shortened stent (the stent having a bead suspended by a tether) into a patient&#39;s ureter  90  without the need for a positioning line to withdraw the bead from the ureter  90  during positioning of the stent. Using the modified pusher apparatus described herein or pusher attachment apparatus attached to a pusher, the bead does not need to be pushed past the ureteral orifice  85  and into the ureter  90 , but remains within the pusher receptacle  17  and can stay within the bladder. Accordingly, the pusher apparatus described herein may reduce irritation to the patient&#39;s ureter and simplify the insertion, when used with a shortened stent with a tethered bead. 
     In accordance with one embodiment, there is provided an apparatus for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead into the opening and at least partially within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher apparatus, for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which extends into the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead into the opening and at least partially within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher apparatus, for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead through the opening and within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher apparatus, for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead through the opening and within the pusher. 
     In accordance with another embodiment, there is provided a pusher apparatus, including: (a) a hollow tube with a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for positioning of a tethered bead into the opening and at least partially within the pusher. 
     In accordance with another embodiment, there is provided a pusher attachment apparatus, including: (a) a hollow tube having a distal end and a proximal end; (b) a connector at the proximal end of the hollow tube for attachment to a pusher having a lumen, whereby the lumen of the pusher may be contiguous with the lumen of the hollow tube; and (c) an opening defined in the peripheral wall of the hollow tube, which extends to the inner hollow portion of the hollow tube and may be sized to allow for positioning of a tethered bead into the opening and at least partially within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher attachment apparatus, including: (a) a hollow tube having a distal end and a proximal end; (b) a connector at the proximal end of the hollow tube for attachment to a pusher having a lumen, whereby the lumen of the pusher may be contiguous with the lumen of the hollow tube; and (c) an opening defined in the peripheral wall of the hollow tube, which reaches the inner hollow portion of the hollow tube and may be sized to allow for positioning of a tethered bead into the opening and at least partially within the pusher attachment apparatus. 
     In accordance with another embodiment, there is provided a commercial package including: (a) a guide wire over which a stent may be pushed; (b) a stent assembly for keeping open body channels and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over the guide wire; (c) a pusher attachment, as described herein, adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening; and (d) a pusher tube adapted to be pushed over the guide wire for advancing the stent relative to the guide wire. 
     In accordance with another embodiment, there is provided a commercial package comprising: (a) a guide wire over which a stent may be pushed; (b) a stent assembly for keeping open body channels and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over the guide wire; and (c) a pusher apparatus, as described herein, adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead into the opening. 
     The guide wire, the stent assembly, the pusher attachment, and the pusher tube may be for use in delivering the stent assembly to a human ureter. The guide wire, the stent assembly, and the pusher apparatus may be for use in delivering the stent assembly to a human ureter. 
     The outer diameter of the hollow tube may be less than the diameter of the bead, provided that the pusher apparatus with a bead positioned within the receptacle is able to pass through the lumen of a cytoscope. The outer diameter of the hollow tube may be approximately the diameter of the bead. The outer diameter of the hollow tube may be greater than the diameter of the bead. 
     Alternatively, the outer diameter of the hollow tube may be greater than the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening. The outer diameter of the hollow tube may be less than the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening, provided that the pusher apparatus with a bead positioned within the receptacle is able to pass through the lumen of a cytoscope. The outer diameter of the hollow tube may be approximately the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening. 
     The opening may be greater than 180° of the circumference of the pusher. The opening may be greater than 185° of the circumference of the pusher. The opening may be greater than 190° of the circumference of the pusher. The opening may be greater than 195° of the circumference of the pusher. The opening may be greater than 200° of the circumference of the pusher. The opening may be greater than 205° of the circumference of the pusher. The opening may be greater than 210° of the circumference of the pusher. The opening may be greater than 210° of the circumference of the pusher. The opening may be greater than 215° of the circumference of the pusher. The opening may be greater than 220° of the circumference of the pusher. The opening may be greater than 225° of the circumference of the pusher. The opening may be greater than 230° of the circumference of the pusher. The opening may be greater than 235° of the circumference of the pusher. The opening may be greater than 240° of the circumference of the pusher. The opening may be greater than 250° of the circumference of the pusher. The opening may be greater than 255° of the circumference of the pusher. The opening may be greater than 260° of the circumference of the pusher. The opening may be greater than 265° of the circumference of the pusher. The opening may be greater than 270° of the circumference of the pusher. The opening may be greater than 280° of the circumference of the pusher. The opening may be greater than 285° of the circumference of the pusher. The opening may be greater than 290° of the circumference of the pusher. The opening may be greater than 295° of the circumference of the pusher. The opening may be greater than 300° of the circumference of the pusher. The opening may be greater than 305° of the circumference of the pusher. The opening may be greater than 310° of the circumference of the pusher. The opening may be greater than 315° of the circumference of the pusher. The opening may be greater than 320° of the circumference of the pusher. The opening may be greater than 325° of the circumference of the pusher. The opening may be greater than 330° of the circumference of the pusher. The opening may be greater than 335° of the circumference of the pusher. The opening may be greater than 340° of the circumference of the pusher. The opening may be greater than 345° of the circumference of the pusher. The opening may be greater than 350° of the circumference of the pusher. The opening may be greater than 355° of the circumference of the pusher. 
     The area adjacent the opening may be reinforced to maintain structural integrity of the pusher tube. The reinforcement may be by the addition of a material that is less flexible than the pusher. The reinforcement may be by the use of a material that is less flexible than the pusher tube adjacent the opening. 
     The minimum distance between the distal end of the pusher and the opening may be about 3 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 5.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 1.9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 7 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 6 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 7 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 6 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 12 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 11 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 2 cm and 10 cm. 
     The minimum distance between the distal end of the pusher attachment and the opening may be about 3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 5.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 1.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 12 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 11 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 8 cm. 
     The pusher apparatus described herein allows for the insertion of a shortened stent (the stent having a bead suspended by a tether) into a patient&#39;s ureter  90  without the need for a positioning line to withdraw the bead from the ureter  90  during positioning of the stent. Using the modified pusher apparatus described herein, the bead does not need to be pushed past the uretal orifice  85  and into the ureter  90 , but remains within the pusher receptacle  17  and can stay within the bladder. Accordingly, the pusher apparatus described herein may reduce irritation to the patient&#39;s ureter and simplify the insertion, when a shortened stent with a tethered bead is used. 
     In accordance with one embodiment, there is provided an apparatus for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead through the opening and within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher apparatus, for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead through the opening and within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher apparatus, for the insertion of a shortened stent, said stent having a bead suspended by a tether, wherein, the pusher includes: (a) a hollow tube having a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for the positioning of the bead through the opening and within the pusher. 
     In accordance with another embodiment, there is provided a pusher apparatus, including: (a) a hollow tube with a distal end and a proximal end; and (b) an opening defined in the peripheral wall of the pusher near the distal end, which reaches the inner hollow portion of the pusher and may be sized to allow for positioning of a tethered bead through the opening and within the pusher. 
     In accordance with another embodiment, there is provided a pusher attachment apparatus, including: (a) a hollow tube having a distal end and a proximal end; (b) a connector at the proximal end of the hollow tube for attachment to a pusher having a lumen, whereby the lumen of the pusher may be contiguous with the lumen of the hollow tube; and (c) an opening defined in the peripheral wall of the hollow tube, which reaches the inner hollow portion of the hollow tube and may be sized to allow for positioning of a tethered bead through the opening and within the receptacle defined by the opening. 
     In accordance with another embodiment, there is provided a pusher attachment apparatus, including: (a) a hollow tube having a distal end and a proximal end; (b) a connector at the proximal end of the hollow tube for attachment to a pusher having a lumen, whereby the lumen of the pusher may be contiguous with the lumen of the hollow tube; and (c) an opening defined in the peripheral wall of the hollow tube, which reaches the inner hollow portion of the hollow tube and may be sized to allow for positioning of a tethered bead through the opening and within the pusher attachment apparatus. 
     In accordance with another embodiment, there is provided a commercial package including: (a) a guide wire over which a stent may be pushed; (b) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over the guide wire; (c) a pusher attachment, as described herein, adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening; and (d) a pusher tube adapted to be pushed over the guide wire for advancing the stent relative to the guide wire. 
     In accordance with another embodiment, there is provided a commercial package including: (a) a guide wire over which a stent may be pushed; (b) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over the guide wire; and (c) a pusher apparatus, as described herein, adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; (b) a pusher attachment as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an holder until a guide wire is inserted; and (c) a pusher tube adapted to be pushed over the guide wire for advancing the stent relative to the guide wire. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; and (b) a pusher apparatus as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an holder until a guide wire is inserted. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; (b) a pusher attachment as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an external holder until a guide wire is inserted; and (c) a pusher tube adapted to be pushed over the guide wire for advancing the stent relative to the guide wire. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; and (b) a pusher apparatus as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an external holder until a guide wire is inserted. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; (b) a pusher attachment as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an internal holder until a guide wire is inserted; and (c) a pusher tube adapted to be pushed over the guide wire for advancing the stent relative to the guide wire. 
     In accordance with another embodiment, there is provided a commercial package including (a) a stent assembly for keeping a body channel open and having a tethered bead for stent retrieval, the stent and bead being adapted to be pushed over a guide wire; and (b) a pusher apparatus as described herein adapted to be pushed over the guide wire to advance the stent relative to the guide wire and to accept the tethered bead within the opening, wherein the tethered bead is retained within the opening by an internal holder until a guide wire is inserted. 
     The holder may internal or external or a combination of both. The holder may be a wrapper. The holder may be a mandrel. 
     The outer diameter of the hollow tube may be less than the diameter of the bead, provided that the pusher apparatus with a bead positioned within the receptacle is able to pass through the lumen of a cytoscope. The outer diameter of the hollow tube may be approximately the diameter of the bead. The outer diameter of the hollow tube may be greater than the diameter of the bead. 
     Alternatively, the outer diameter of the hollow tube may be greater than the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening. The outer diameter of the hollow tube may be less than the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening, provided that the pusher apparatus with a bead positioned within the receptacle is able to pass through the lumen of a cytoscope. The outer diameter of the hollow tube may be approximately the diameter of the bead plus the cross-sectional area of the peripheral wall of the pusher opposite the opening. 
     The opening may be greater than 180° of the circumference of the pusher. The opening may be greater than 185° of the circumference of the pusher. The opening may be greater than 190° of the circumference of the pusher. The opening may be greater than 195° of the circumference of the pusher. The opening may be greater than 200° of the circumference of the pusher. The opening may be greater than 205° of the circumference of the pusher. The opening may be greater than 210° of the circumference of the pusher. The opening may be greater than 210° of the circumference of the pusher. The opening may be greater than 215° of the circumference of the pusher. The opening may be greater than 220° of the circumference of the pusher. The opening may be greater than 225° of the circumference of the pusher. The opening may be greater than 230° of the circumference of the pusher. The opening may be greater than 235° of the circumference of the pusher. The opening may be greater than 240° of the circumference of the pusher. The opening may be greater than 250° of the circumference of the pusher. The opening may be greater than 255° of the circumference of the pusher. The opening may be greater than 260° of the circumference of the pusher. The opening may be greater than 265° of the circumference of the pusher. The opening may be greater than 270° of the circumference of the pusher. The opening may be greater than 280° of the circumference of the pusher. The opening may be greater than 285° of the circumference of the pusher. The opening may be greater than 290° of the circumference of the pusher. The opening may be greater than 295° of the circumference of the pusher. The opening may be greater than 300° of the circumference of the pusher. The opening may be greater than 305° of the circumference of the pusher. The opening may be greater than 310° of the circumference of the pusher. The opening may be greater than 315° of the circumference of the pusher. The opening may be greater than 320° of the circumference of the pusher. The opening may be greater than 325° of the circumference of the pusher. The opening may be greater than 330° of the circumference of the pusher. The opening may be greater than 335° of the circumference of the pusher. The opening may be greater than 340° of the circumference of the pusher. The opening may be greater than 345° of the circumference of the pusher. The opening may be greater than 350° of the circumference of the pusher. The opening may be greater than 355° of the circumference of the pusher. 
     The area adjacent the opening may be reinforced to maintain structural integrity of the pusher tube. The reinforcement may be by the addition of a material that is less flexible than the pusher. The reinforcement may be by the use of a material that is less flexible than the pusher tube adjacent the opening. 
     The minimum distance between the distal end of the pusher and the opening may be about 3 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 5.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 4.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.5 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 3.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.9 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.8 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.7 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.6 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.4 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.3 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.2 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.1 cm. The minimum distance between the distal end of the pusher and the opening may be about 2.0 cm. The minimum distance between the distal end of the pusher and the opening may be about 1.9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 7 cm. The minimum distance between the distal end of the pusher and the opening may be between about 5 cm and 6 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 7 cm. The minimum distance between the distal end of the pusher and the opening may be between about 4 cm and 6 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 12 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 11 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 10 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 9 cm. The minimum distance between the distal end of the pusher and the opening may be between about 3 cm and 8 cm. The minimum distance between the distal end of the pusher and the opening may be between about 2 cm and 10 cm. 
     The minimum distance between the distal end of the pusher attachment and the opening may be about 3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 5.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 4.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.5 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 3.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.4 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.3 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.2 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.1 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 2.0 cm. The minimum distance between the distal end of the pusher attachment and the opening may be about 1.9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 5 cm and 6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 7 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 4 cm and 6 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 12 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 11 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 10 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 9 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 3 cm and 8 cm. The minimum distance between the distal end of the pusher attachment and the opening may be between about 2 cm and 10 cm. 
     The tether connecting the bead and the stent, may be made available in variable diameters. Particularly, in the event that drainage would be useful. For example, occasionally, after the ureter has been traversed with an instrument it may be traumatized causing edema and obstruction of the urinary flow. When there is swelling in the intramural (bladder portion) of the ureter, drainage of the ureter may assist with reducing the swelling. Generally, a stent will allow for drainage of the ureter, but in some instances the swelling may be such that the stent alone is not sufficient to provide drainage, in particular, where a shortened stent is used. In such circumstances the tether may also assist with drainage of the ureter. A larger diameter tether or possibly even a flat tether may help with drainage. Alternatively, tether with other non-circular cross-sections may be appropriate in the circumstances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In drawings which illustrate embodiments of the invention: 
         FIG. 1  is a side view of a modified pusher apparatus according to a first embodiment; 
         FIG. 2  is a side view of a modified pusher apparatus according to a second embodiment, wherein the area adjacent the opening is reinforced; 
         FIG. 3  is a side view of a pusher attachment apparatus according to an embodiment adjacent to an unmodified pusher; 
         FIG. 4  is a partial cross-sectional view of the modified pusher apparatus of  FIG. 1 , adjacent to a stent assembly having a tether and a bead, all threaded over a guide wire, wherein the bead is positioned within the opening of the modified pusher apparatus; 
         FIG. 5  is a cross-sectional view of the modified pusher apparatus of  FIG. 1 , positioned within a cytoscope, threaded over a guide wire, with a bead positioned within the opening of the modified pusher apparatus; 
         FIG. 6  illustrates a shortened stent positioned within the ureter and a tethered bead suspended in the bladder; 
         FIG. 7  illustrates a shortened stent positioned within the ureter and a prior art tethered bead suspended in the bladder; and 
         FIG. 8  illustrates a shortened stent positioned within the ureter and a larger tethered bead than in  FIG. 6 , suspended in the bladder. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein a “bead” is meant to include any ferromagnetic member. Ferromagnetic as used herein is meant to include materials which may comprised of iron, nickel, chromium, or cobalt or combinations thereof and various alloys, such that the bead is attracted to a magnet. For example, a bead may be made from ferromagnetic stainless steel. Furthermore, beads are preferably biocompatible. For example, a stainless steel bead may be coated with a smooth layer of polymer, for example, polytetrafluoroethylene. A “biocompatible” bead or a bead coated with a biocompatible coating, may prevent the reaction of the bead with urine or bile, or other bodily fluids in which the bead may be placed. Furthermore, the bead may itself be a magnet. Beads as described herein are generally biocompatible, rounded, perforated, and ferromagnetic. For example, a bead may be made from a rare earth magnet or a stainless steel having magnetic properties. 
     A pusher is essentially a hollow tube, which may be made in a variety of diameters and having a range of wall thicknesses, and may be selected to ensure compatibility for use with a given stent. A pusher may be made from high durometer (stiff), biocompatible, polymers and polymer blends (for example, polyurethane, high density polyethylene, nylon, etc. and blends thereof), as known in the art. 
     A holder as used herein, is meant to include any member that is capable of retaining a bead within an opening of a modified pusher apparatus or a pusher attachment, to facilitate the insertion of a guide wire through the bead, while the bead is within the opening of the modified pusher apparatus or the pusher attachment. The holder may be removed after insertion of a guide wire or may remain associated with the modified pusher apparatus or the pusher attachment, but be in a release position so that when the guide wire is removed during s stent insertion, the bead may be released from the modified pusher apparatus or the pusher attachment. A commercial package containing such a holder, may facilitate loading of a selected guide wire, for insertion into the apparatus. A holder may be internal or external or a combination thereof. Furthermore, a holder may, for example, take the form of a removable wrapper, a clip, a mandrel, a wedge, an adhesive surface modification etc. An adhesive surface modification, may be prepared such that the adhesive dissolves when in situ (for example, in urine, at body temperature, etc.). Such a system allows for the selection of the best guide wire to suit the patient or the personal preferences of the user. For example, guide wires may be chosen for their frictional properties (for example, a hydrophilic coating may provide for less friction) or their ‘pushability’. 
     A mandrel, as used herein, may be a wire that resides within the modified pusher apparatus or a pusher attachment, to hold the bead within the opening of the modified pusher apparatus or the pusher attachment until the guide wire is inserted. The mandrel may be sized to fit within the bead with the guide wire or such that it is pushed out of the bead as the guide wire is inserted. 
     A wrapper, as used herein, may be any type of protective covering that is capable of retaining a bead within the opening of a modified pusher apparatus or a pusher attachment, to facilitate the insertion of a guide wire through the bead. Such a wrapper may be removed once the guide wire is inserted through the bead. 
     Referring to  FIG. 1 , a modified pusher apparatus according to a first embodiment is shown generally at  10 . The inner hollow portion or lumen of the pusher is shown at  14  and the distal end of the modified pusher apparatus is shown at  19 . The modified pusher apparatus has a receptacle  17 , which is defined by an opening  15 . The lumen of the pusher may receive a guide wire (not shown in  FIG. 1 ) and the receptacle  17  is sized and positioned near the distal end of the pusher  19  to receive a tethered bead attached to the proximal end of the stent (the bead and stent are not shown in  FIG. 1 ). 
     Referring to  FIG. 2 , a modified pusher apparatus according to a second embodiment is shown generally at  10 . Similar to  FIG. 1 , the inner hollow portion or lumen of the pusher is shown at  14  and the distal end of the modified pusher apparatus is shown at  19 . The modified pusher apparatus has a receptacle  17 , which is defined by an opening  15 . The lumen of the pusher may receive a guide wire (not shown in  FIG. 2 ) and the receptacle  17  is sized and positioned near the distal end of the pusher  19  to receive a tethered bead attached to the proximal end of the stent (the bead and stent are not shown in  FIG. 2 ). However, the modified pusher of  FIG. 2  has a reinforced area  20  adjacent the opening to maintain the structural integrity of the pusher tube despite the opening  15  in the wall of the pusher tube. The reinforced area  20  may be made of a different material than the remainder of the pusher or the reinforced area  20  may have added material that is the same as or different than the remainder of the pusher. Furthermore, the reinforced area  20  may be made of a material that is less flexible than the remainder of the pusher or the reinforced area  20  may have added material that is less flexible than the remainder of the pusher. The reinforcement applied in the reinforced area  20  adjacent the opening and the size of the area to be reinforced  20  may depend on a number of factors, which may include the size of the opening  15 , the shape of the opening  15 , the properties of the material from which the remainder of the pusher is made, the properties of the material adjacent the opening  15 , the properties of the material defining the borders of the receptacle  17 , and the use in which the pusher is to be implemented. In view of the above a person of skill in the art would be well aware of the reinforcement that may be applied to maintain the structural integrity of the pusher. The reinforced area, for example, may be made from stainless steel or another alloy. 
     Referring to  FIG. 3 , a pusher attachment apparatus according to an embodiment is generally shown at  100 . The inner hollow portion or lumen of the pusher attachment apparatus is shown at  140 , the inner hollow portion or lumen of the pusher is shown at  141 , and the distal end of the pusher apparatus is shown at  190 . The pusher attachment apparatus has a receptacle  17 , which is defined by an opening  15 . The lumen of the pusher may receive a guide wire (not shown in  FIG. 3 ) and the receptacle  17  is sized and positioned to receive a tethered bead attached to the proximal end of the stent (the bead and stent are not shown in  FIG. 3 ). The pusher attachment apparatus may be designed, to be attached to any standard pusher apparatus to allow for the positioning of a bead, which is tethered to a stent, within the receptacle  17 . 
     Referring to  FIG. 4 , a modified pusher apparatus according to a first embodiment is shown in a partial cross-section generally at  10 , adjacent a partial cross-section of a shortened stent  30 . The stent  30  is positioned along a guide wire  50  at the distal end  19  of the modified pusher  10 , whereby the distal end  19  of the modified pusher  10  is adjacent to the proximal end  39  of the stent  30 . The guide wire  50  is shown, from proximal to distal (left to right), passing through the inner hollow portion or lumen  14  of the modified pusher apparatus  10 , passing through the bore or perforation in the bead  40 , through the remainder of the lumen  14  of the modified pusher apparatus  10 , and passing through the inner hollow portion or lumen  34  of the stent  30 . The modified pusher apparatus has a receptacle  17 , which is defined by an opening  15 . The bead  40  is shown positioned near the distal end of the pusher  19 , within the receptacle  17  and with the guide wire passing through the bore within the bead. A tether  60  is shown looping around the exterior of the stent and passing through a stent perforation  36 , passing through the inner hollow portion or lumen  34  of the stent  30  to the proximal end of the stent  39 , then along the outer surface of the modified pusher apparatus  10 , to the bead  40  and through the tether opening  43  of the bead, wherein the tether opening as shown is generally extend through the bead perpendicular to the long axis of the bead. As shown in  FIG. 4 , only one side of the tether loop is shown between the bead and the stent lumen. 
     Referring to  FIG. 5 , a modified pusher apparatus according to a first embodiment is shown in a partial cross-section generally at  10 , positioned within the lumen  74  of a cytoscope  70 . The bead  40  is shown in cross-section positioned within the receptacle  17  adjacent the distal end  19  of the modified pusher  10 , whereby the distal end  19  of the modified pusher  10  is adjacent to the distal end  79  of the cytoscope  70 . Also shown, is the bead tether opening  43 , but the tether is not shown. The guide wire  50  is shown, from proximal to distal (bottom left to top right), passing through the inner hollow portion or lumen  14  of the modified pusher apparatus and through the lumen of the cytoscope  74 , passing through the bore or perforation in the bead  40 , through the remainder of the lumen  14  of the modified pusher apparatus  10 , and passing through the inner hollow portion or lumen  34  of the stent  30 . 
     Referring to  FIGS. 6, 7, and 8 , shortened stents are shown positioned within the ureter  90 , following insertion with the insertion apparatus removed (i.e. cytoscope, pusher and guidewire). The stent assembly, which includes the shortened perforated stent  30 , tether  60 , and bead  40  are shown in  FIGS. 6, 7, and 8  with three different bead designs. The bead design in  FIG. 7  is reproduced from the PCT application PCT/CA99/00405. The positioning of the stent assembly is such that the proximal end of the stent  39  is positioned within the ureter  90  and away from the ureteral orifice  85  and whereby the bead  40  is suspended in the bladder  80  by the tether  60 , which passes through the bead tether opening  43 .  FIG. 7  also shows a passage for a positioning line  45  within the bead (positioning line not shown).  FIG. 6  shows a larger bead design relative to  FIG. 8 . Nevertheless, the shorter bead designs of  FIGS. 6 and 8  may permit better rotation on the tether, as compared to the bead of  FIG. 7 , which may assist in release of the tethered bead from the pusher apparatus or pusher attachment (not shown in  FIGS. 6-8 ). 
     Referring to  FIGS. 4-8 , the bead tether opening  43  as shown is generally at a midpoint in the bead  40  to allow the bead to lie perpendicular to the ureteric orifice  85  and prevent migration up the ureter  90 . 
     The operation of the modified pusher apparatus for the insertion of a shortened stent  30  into a ureter  90  may be described as follows:
         a cytoscope  70  is inserted into the bladder, and a guide wire  50  is passed up the cytoscope lumen  74  to the bladder and up the ureter into a kidney;   a shortened stent  30  is threaded onto the guide wire  50 , without threading the bead  40 , followed by the modified pusher apparatus  10  until the guide wire approaches the receptacle  17 ,   the bead  40  tethered to the stent  39  is positioned within the receptacle  17  such that the guide wire  50  may pass through the bead and towards the proximal end of the pusher (alternatively, the stent  30 , pusher  10 , bead  40  and guidewire  50  may be preassembled to allow for insertion as a unit);   the shortened stent  30  followed by the modified pusher apparatus  10 , with the bead  40  positioned within the receptacle  17  and held in place by the guide wire, are advanced up the guide wire  50  and through the cytoscope  70  into the bladder  80 ;   the shortened stent  30  and the modified pusher apparatus  10  are further advanced up the ureter so that the hook or pigtail (not shown) on the distal end of the stent is positioned within the kidney and the proximal end of the stent  39  is positioned within the ureter  90  as shown in  FIGS. 6-8 ;   the cytoscope  70 , which is situated in the bladder  80 , is used to visually confirm (fluoroscopic confirmation) the correct positioning of the stent  30  based on the position of the modified pusher apparatus  10  relative to the uretal orifice  85  (such a fluoroscopic confirmation may be simplified, where the pusher has markings or gradations so that the operator can gauge the depth of the stent within the ureter);   the modified pusher apparatus  10  is held in position adjacent the proximal end of the stent  39 , while the guide wire  50  is removed so that the shortened stent  30  does not slide down the ureter  90  (from distal to proximal) as the guide wire is withdrawn from the ureter; and   the modified pusher apparatus  10  is withdrawn into the cystoscope and removed together with the cytoscope  70  (to avoid damaging the urethra with the receptacle  17 ).       

     Removal of the stent  30  may be accomplished by a non-surgical procedure that does not even require endoscopy. As described in an earlier patent application (WO99/58083) a retrieval catheter (not shown), which comprises a conventional catheter that is modified to mount a magnet at the distal tip of the catheter. The magnet may also be covered with a biocompatible coating and/or may be rounded to prevent injury to the patient. The magnet-tipped end of the retrieval catheter is inserted, through the urethra and into the bladder, where the catheter tip magnetically engages the suspended bead  40 . As the catheter is withdrawn the bead  40  and tether-connected stent  30  are pulled from the ureter and explanted from the patient. 
     As the retrieval catheter approaches the bead  40 , the magnetic flux acting on the bead  40  should be sufficient to cause the bead to rotate relative to the tether from its normal, suspended position, so that one of the ends of the bead  40  rotates on the tether to contact the tip of the retrieval catheter. Accordingly, the bead will be oriented generally coaxially with the end of the retrieval catheter. If this orientation is not attained in the bladder, as the retrieval catheter and bead enter the urethra passage, the urethra will likely cause the axial alignment of the bead  40  with the retrieval catheter, which is desired for comfortable removal of the bead through the urethra. It will be appreciated that this rotation of the bead will be assured where the bead is magnetized, and one of its ends has a polarity opposite that of the magnet on the retrieval catheter. 
     Alternatively, the bead  40  could be a magnet and the retrieval catheter tipped with ferromagnetic material or another magnet. Although a rare-earth magnet is preferred, other types, including electromagnets could be employed with the retrieval catheter. In addition, the bead may be of a more ball shape  FIGS. 6 and 8 , rather than the elongated bead of  FIG. 7 . 
     Although various embodiments of the invention are disclosed herein, many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. Numeric ranges are inclusive of the numbers defining the range. The word “comprising” is used herein as an open-ended term, substantially equivalent to the phrase “including, but not limited to”, and the word “comprises” has a corresponding meaning. As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a thing” includes more than one such thing. Citation of references herein is not an admission that such references are prior art to an embodiment of the present invention. Any priority document(s) and all publications, including but not limited to patents and patent applications, cited in this specification are incorporated herein by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein and as though fully set forth herein. The invention includes all embodiments and variations substantially as hereinbefore described and with reference to the examples and drawings.