Abstract:
A method for creating a tract for nephrostomy tube creation comprising the steps of providing a puncture wire having a tissue penetrating tip shielded in a sheath, the puncture wire slidable within the sheath and releasably lockingly engaged thereto, inserting the puncture wire and sheath in a first direction through a working channel of an ureteroscope to exit the channel of the ureteroscope, releasing the puncture wire from the sheath and advancing the puncture wire a first distance from the sheath while visualizing via the ureteroscope the position of the puncture wire, advancing the puncture wire and the sheath into a selected calyx and through a flank of a patient, removing the puncture wire from the sheath in a second direction different from the first direction and inserting a guidewire through the sheath.

Description:
This application claims priority from provisional application No. 61/498,644, filed Jun. 20, 2011, provisional application No. 61/498,393, filed Jun. 17, 2011, provisional application No. 61/496,950, filed Jun. 14, 2011, provisional application No. 61/475,318, filed Apr. 14, 2011, provisional application No. 61/473,906, filed Apr. 11, 2011, provisional application No. 61/446,294, filed Feb. 24, 2011, provisional application No. 61/413,598, filed Nov. 15, 2010, provisional application No. 61/413,977, filed Nov. 15, 2010, provisional application No. 61/413,981, filed Nov. 15, 2010, provisional application No. 61/413,993, filed Nov. 16, 2010, provisional application No. 61/421,071, filed Dec. 8, 2010, provisional application No. 61/422,202, filed Dec. 12, 2010, and provisional application No. 61/424,041, filed Dec. 16, 2010. The entire contents of each of these applications are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     This application relates to a percutaneous puncture system and more particularly to a percutaneous puncture system and method for creating a tract for nephrostomy tube creation. 
     2. Background of Related Art 
     Nephrostomy is the creation of a communication between the skin and kidney to provide for nephrostomy tube insertion. The objective in nephrostomy tube creation is to have the wire from outside the flank directed down the ureter to provide therapeutic drainage of an obstructed system. This allows for subsequent dilation of the tract, such as by a nephrostomy dilating balloon, between the kidney and the skin over a wire that extends down the ureter. The catheter and tract can also be used to facilitate stenting of a narrowed ureter or removal or treatment of stones obstructing the ureter. Current nephrostomy tube creation is dependent on x-ray exposure to guide the physician where to locate the nephrostomy puncture wire tract. 
     There are currently two widely used techniques for nephrostomy tube creation. One technique utilizes an antegrade approach. The antegrade approach holds increased bleeding risk due to the puncture needle puncturing the interlobar arteries as it passes into the collecting system. This antegrade approach is also skill intensive because it requires advancing from the flank to an “unknown” calyx. In fact, studies have shown that recent urology resident graduates often do not continue to perform the antegrade nephrostomy technique after graduating due to difficulty of this procedure. The procedure also requires a relatively large amount of radiation exposure. 
     The other technique commonly utilized is the Lawson technique. This technique is used to create a nephrostomy tract in a retrograde fashion. The Lawson technique is performed under fluoroscopy utilizing a deflecting wire inside a ureteric catheter to select the renal calyx to be entered. That is, fluoroscopy is used to identify the renal calyx for nephrostomy access. The Lawson technique is described for example in Smith&#39;s Textbook of Urology, 2007, BC Decker Inc., “Retrograde Access” by Dennis H. Hosking and is commercially available by Cook Urological, Inc. as the “Lawson Retrograde Nephrostomy Wire Puncture Set.” 
     In the Lawson technique, a stainless steel 145 cm long guidewire (0.038 inches in diameter) having a 3 cm flexible tip is passed retrograde up the ureter into the renal pelvis under fluoroscopy. A 7 Fr catheter is passed over the guidewire into the renal pelvis and the guidewire is removed. A J-tipped wire in certain instances might be used to facilitate passage past an obstruction. Then the surgeon selects the optimal calyx for nephrostomy placement, optimization usually being defined by allowing easiest access to the renal calculi and the shortest tract. 
     Once the calyx is selected, the 0.045 inch diameter deflecting wire guide is inserted through the lumen of the catheter and twist locked to the proximal end of the catheter. Deflection of the wire tip deflects the tip of the catheter, and the catheter and attached wire can be advanced into the selected calyx. However, it is recognized that due to obstructions, e.g. presence of calculi, it may not be possible to advance the catheter into the optimally desired calyx and consequently a less optimal calyx is selected by the surgeon. 
     After insertion of the catheter into the selected calyx, the deflecting wire guide is removed from the lumen of the catheter, while maintaining the inner-calyx position of the catheter tip. A puncture wire and sheath as a unit are inserted through the catheter lumen, with the puncture wire sharp tip shielded by the sheath. During insertion through the catheter, the wire remains retracted within the sheath, and locked to the sheath by a pin vise lock, so its puncture tip is not exposed. The puncture wire and sheath are connected/locked to the proximal portion of the catheter. The puncture wire is then unlocked from the sheath, by untwisting the cap of the pin vise actuator to loosen the vise pin grip on the puncture wire, and then incrementally advanced from the distal end of the sheath through the flank, fascia and skin. After puncturing the skin, the puncture wire is advanced from below until approximately 15 cm of wire is externally visible. 
     The pin vise lock securing the puncture wire to the insulating sheath is then re-locked. A fascial incising needle may or may not be passed over the puncture wire at the flank to incise fascia, and is then removed. As the 7 French catheter is advanced through the cystoscope below, the puncture wire is drawn further out of the flank, until the tip of the 7 French catheter is delivered out of the flank. At this time, the 7 French catheter is unlocked from its connection to the puncture wire assembly, and the puncture wire and insulating sheath are removed from below. A 0.038″ guidewire is then passed antegrade through the 7 French catheter from the flank, until it emerges out the lower end of the 7 French catheter at the cystoscope end. With this wire ‘through and through’ the body, the cystoscope and 7 French catheter are removed, leaving the guidewire in place. 
     The retrograde Lawson approach has several advantages over the antegrade approach including providing the surgeon an anatomic approach to the renal pelvis, increased likelihood of avoiding the interlobar arteries during puncture, and inherently having a wire down the ureter, an important step in securing control over the nephrostomy tract. It is also less skill intensive, due in large part to the fact that it enables travel from the “known kidney” to the “unknown flank/skin,” which better respects the principles of surgery. 
     However, despite its advantages over the antegrade approach, there are several disadvantages to the Lawson technique. First, although requiring less radiation exposure, the patient is oftentimes still exposed to harmful doses of radiation. Secondly, it is often difficult to navigate the ureteric catheter beyond large obstructive stones in the renal pelvis. This inability to direct the catheter to the desired site (calyx) often leads the surgeon to access a less optimal calyx. Thirdly, fluoroscopy provides only a two dimensional view of the renal anatomy, thereby limiting the ability to confidently select the calyx for tract dilation. Sometimes, there is even uncertainty as to which calyx is actually chosen due to the limited visibility provided by fluoroscopy. 
     Consequently, it would be advantageous to provide a system and method that enables more precise calyx location, improves access to the calyx of choice, improves visualization, permits “fluoroscopy-free” calyx selection, and allows for preliminary laser lithotripsy of a portion of a stone that may block access to calyx of choice for nephrostomy creation. Also of significance is that nephrostomy tube creation procedures are usually performed by interventional radiologists, which can further compound the risks and problems since urologists usually have better success rates for selecting the calyx for such procedures. Thus, it would be advantageous if such improved system and method could be more commonly performed by urologists. 
     In an attempt to address some of the disadvantages of the Lawson technique, Dr. Larry C. Munch in an article entitled “Direct-Vision Modified Lawson Retrograde Nephrostomy Technique Using Flexible Ureteroscope” and published in the Journal of EndoUrology, Volume 3, Number 4, 1989, described a technique utilizing a flexible ureteroscope. 
     In this “Munch technique,” a flexible steerable ureteroscope was utilized to inspect the renal pelvis and calices. As described, a flexible cystoscopy is performed and a 0.035 inch, 145 cm guidewire is passed into the ureteral orifice. Position within the ureter is assessed with fluoroscopy. The cystoscope is removed and a ureteral access sheath with its obturator is advanced over the guidewire, and the obturator is then removed and the ureteroscope is passed through the sheath into the renal pelvis. An appropriate calyx is chosen visually, and then the 0.0017 inch Lawson puncture wire and protective 3Fr radiopaque Teflon sheath is passed through the working channel of the ureteroscope. The calyx is entered and the sheath embedded in the wall of the calyx, and then the pin-vise lock which locks the puncture wire and sheath together is opened and the puncture wire is advanced through the skin under visual and fluoroscopic control. The puncture wire protective sheath and ureteroscope are then withdrawn, leaving the puncture wire and ureteral access sheath in place. At the skin, an 18 gauge needle is passed over the puncture wire into the kidney and then removed. A 9 French fascial dilator is then passed over the 0.017 inch puncture wire into the kidney, whereafter the puncture wire is removed and a 0.038 inch guidewire is passed through the 9 French dilator until it passes down the ureter through the access sheath, and exits through the urethra. 
     Although the Munch technique solves some of the problems associated with the Lawson technique, it is deficient in several respects. First, the Munch technique leaves the puncture wire exposed to the ureteropelvic junction. This creates the risk of cutting inside tissue, especially at the ureteropelvic junction, across which the very thin puncture wire passes. For example, tension on the puncture wire at the time of passing the antegrade exchange catheter may result in internal ‘slicing’ of the ureteropelvic junction by the thin puncture wire. Second, at the time of deployment of the puncture wire, the Munch technique fails to secure the wire assembly and ureteroscope, forcing either the surgeon or an assistant to devote two hands to opening the pin-vise lock and advancing the puncture wire, all while holding the flexible ureteroscope in position in a selected calyx. This makes wire deployment cumbersome for the surgeon, less likely to be successful, requiring more skilled assistance, and increases the chances the tip of the flexible cystoscope will move out of a selected location for nephrostomy creation. Third, Munch&#39;s technique of antegrade wire exchange is ineffectual and risks cutting the puncture wire with passage of 18 gage hollow bore needle over the wire. After passage of this needle, a 9 French fascial dilator is passed over the 0.017″ puncture wire, representing a wire-catheter mismatch which can result in tearing of internal tissues. This large jump from an 18 gauge needle to a 9 French fascial dilator is also cumbersome and has a high chance of failing to grant access to the kidney. 
     Consequently, it would be advantageous to provide a system and method that would enable urologists to more economically and efficiently perform the nephrostomy procedure to obtain access for nephrostomy tube creation. Such procedure would have the above-noted advantages over the Lawson technique, e.g. improving calyx access, visualization etc., while also providing the advantages of reducing the number of surgical steps and securing the position of the components and protecting the puncture wire, especially at the ureteropelvic junction, thereby providing advantages over the Munch technique. 
     SUMMARY 
     The present invention overcomes the disadvantages and deficiencies of the prior art. The present invention provides in one aspect a method for creating a tract in retrograde fashion for nephrostomy tube creation comprising the steps of providing a puncture wire having a tissue penetrating tip shielded in a sheath, inserting the puncture wire and sheath through a channel in an ureteroscope, and securing the sheath to the ureteroscope. The method further includes the steps of advancing the puncture wire from the sheath while visualizing under direct vision the position of the puncture wire and advancing the puncture wire into a selected calyx with the sheath secured to the ureteroscope. 
     In preferred embodiments, the sheath and puncture wire are releasably locked together, and the method further comprises the step of releasing the puncture wire from the sheath, which in some embodiments can be achieved by unlocking a vise lock on the sheath. 
     Preferably, the method further comprises the step of selecting a calyx under direct visualization prior to advancing the puncture wire into the selected calyx. 
     The method can include the step of loading in antegrade fashion a sheath over the puncture wire with the ureteroscope remaining within a body of the patient. 
     In some embodiments, the method includes removing the sheath from the channel of the ureteroscope after the step of advancing the puncture wire through the calyx, flank and skin of a patient and subsequently inserting a second sheath through the channel over the puncture wire. The second sheath can be advanced through the flank and in preferred embodiments is advanced after relocking the sheath to the puncture wire. In these embodiments, preferably subsequently the puncture wire is removed from the second sheath and a guidewire is advanced through the second sheath. In some embodiments, the first sheath and puncture wire are inserted in a first direction and the second sheath is inserted in the first direction after removal of the first sheath in a second direction. 
     The method may include the step of removing the puncture wire and ureteroscope from a body of the patient while leaving the sheath in position to subsequently receive a guidewire therethrough, the sheath functioning as an exchange sheath. 
     In preferred embodiments, the method further comprises the step of providing a locking mechanism mountable to the ureteroscope wherein the locking mechanism has an opening to receive the sheath and puncture wire therethrough and is actuable to secure the sheath to the ureteroscope. 
     The method may also include the step of performing uteroscopic lithotripsy through the ureteroscope to remove a calyx blocking stone prior to inserting the puncture wire into the working channel of the ureteroscope. 
     In another aspect, the present invention provides a method for creating a tract for nephrostomy tube creation comprising the steps of:
         a) providing a puncture wire having a tissue penetrating tip shielded in a sheath, the puncture wire slidable within the sheath and releasably lockingly engaged thereto;   b) inserting the puncture wire and sheath in a first direction through a working channel of an ureteroscope to exit the working channel of the ureteroscope;   c) releasing the puncture wire from the sheath and advancing the puncture wire a first distance from the sheath while visualizing the position of the puncture wire;   d) advancing the puncture wire and the sheath into a selected calyx and through the flank of a patient;   e) removing the puncture wire from the sheath in a second direction different from the first direction; and   f) inserting a guidewire through the sheath.       

     In some embodiments, the guidewire is inserted in a second direction through the sheath. The ureteroscope in some embodiments is removed in the second direction prior to the step of inserting a guidewire through the sheath. 
     In some embodiments, the puncture wire is first inserted through the flank and out the skin, and subsequently the sheath is advanced over the puncture wire through the flank. This can occur after re-locking the pin-vise mechanism. In other embodiments, the puncture wire is advanced a short distance from the sheath, e.g. approximately 1 cm, then re-locked to the sheath with the pin-vise, and the puncture wire/sheath duo are together inserted through the flank and out the skin and locked against sliding movement during insertion. 
     In some embodiments, after advancement of the puncture wire through the flank, the puncture wire is locked against movement. The puncture wire can have one or more markers thereon to indicate the extent of advancement from the sheath. 
     In another aspect, the present invention provides a method for creating a tract for nephrostomy tube creation comprising the following steps:
         a) providing a puncture wire having a tissue penetrating tip shielded in a first sheath, the puncture wire slidable within the first sheath and releasably lockingly engaged thereto;   b) inserting the puncture wire and first sheath in a first direction through a working channel of an ureteroscope to exit the working channel of the ureteroscope;   c) releasing the puncture wire from the first sheath and advancing the puncture wire a first distance from the first sheath while visualizing the position of the puncture wire;   d) advancing the puncture wire and the first sheath from within a selected calyx and through the flank of a patient;   e) removing the first sheath in a second direction different from the first direction;   f) inserting a second longer sheath over the puncture wire through the channel of the ureteroscope; and   g) removing the puncture wire from the second sheath and ureteroscope.       

     In this method, preferably a guidewire is inserted through the second sheath after the step of removing the puncture wire from the second sheath. 
     The puncture wire can be relocked to the second sheath. In some embodiments, the second sheath is longer than the first sheath. 
     In some embodiments, the second sheath is inserted in the first direction; in other embodiments it is inserted in a second direction. 
     In yet another aspect of the present invention, a method of creating a tract for nephrostomy tube creation is provided which comprises the steps of providing a wire having a proximal end and a distal end with a puncture tip at the distal end, inserting the wire without a sheath directly into a working channel of an ureteroscope and advancing the wire from the channel so the puncture tip extends through the flank of a patient. Subsequent to advancement of the puncture tip through the flank, the method includes the steps of loading a sheath over the wire and through the working channel of the ureteroscope and thereafter removing the wire from the channel of the ureteroscope. 
     The method can further comprise the step of inserting a guidewire through the sheath after the step of removing the wire from the sheath and the channel of the ureteroscope. The sheath in some embodiments is loaded in an antegrade fashion; in other embodiments it is loaded in a retrograde fashion. The wire can be loaded initially through the proximal opening in the working channel. The method in some embodiments can include loading a dilation balloon over the guidewire. 
     The present invention also provides in another aspect a method for wire exchange to create a tract under direct visualization for nephrostomy tube creation while shielding the wire. The method comprises the following steps:
         a) providing a puncture wire having a tissue penetrating tip shielded in a first sheath;   b) inserting the puncture wire and first sheath through a channel in an ureteroscope;   c) advancing the puncture wire from the first sheath while visualizing under direct vision the position of the puncture wire;   d) advancing the puncture wire into a selected calyx;   e) removing the first sheath from the channel while leaving the ureteroscope in place to shield a portion of the wire that bends around the ureteropelvic junction to reduce tissue trauma;   f) inserting a second sheath over the puncture wire while the puncture wire remains in the channel;   g) advancing the second sheath from the channel under direct vision; and   h) inserting a second wire through the second sheath after removal of the puncture wire therefrom.       

     In preferred embodiments, the first sheath is secured to the ureteroscope during the step of advancing the puncture wire into the selected calyx, and through the kidney and out the flank. Also, preferably, the puncture wire is releasably locked to the first sheath and subsequently releasably locked to the second sheath. 
     The present invention also provides in another aspect an exchange sheath for use with a working channel of an ureteroscope. The exchange sheath comprises a lumen dimensioned to slidingly receive a puncture wire having a penetrating tip and a first diameter, the puncture wire releasably locked to the exchange sheath. The puncture wire is movable distally out of the lumen of the exchange sheath to expose its penetrating tip to puncture tissue and movable proximally for separation from the sheath and removal from a patient&#39;s body with the sheath remaining in the body. The sheath is dimensioned to receive a guidewire through its lumen, while remaining in the body, the guidewire having a second diameter different, e.g. larger, than the first diameter of the puncture wire. The guidewire is receivable through the lumen of the sheath. 
     In preferred embodiments, the sheath remains in the working channel of the ureteroscope during insertion of the guidewire therethrough. In some embodiments, the sheath has a diameter of between about 0.038 to about 0.052 inches. In some embodiments, the sheath has a length of about 90 cm to about 115 cm. The puncture wire can have a length of about 90 cm to about 165 cm. 
     In some embodiments, a first locking mechanism for locking the puncture wire and sheath can be provided and a second locking mechanism for locking the sheath and the ureteroscope can be provided. 
     In some embodiments, the sheath locking mechanism comprises a clamping member having an opening of a first dimension, the opening changeable to a second dimension to provide a clamping force on the sheath. The locking mechanism can be mounted directly to the ureteroscope. The locking mechanism can be releasably mounted to the sheath. 
     In another aspect, the present invention provides a system for accessing a select calyx for kidney surgery comprising a flexible ureteroscope having a proximal portion and a distal portion, and a wire having a penetrating tip at a distal end. The wire is configured and dimensioned for insertion through the ureteroscope and advanceable distally of the distal portion of the ureteroscope for visualization of the wire. The wire is insertable and advanceable through the ureteroscope without a protective sheath. 
     The system may further comprise a sheath advanceable into the ureteroscope subsequent to advancement of the wire through a flank of a patient. In some embodiments, the puncture wire has a diameter of about 0.013 inches to about 0.025 inches. 
     Also provided, in another aspect, is a system for accessing a select calyx for kidney surgery comprising a first wire having a penetrating tip at a distal end and having a first diameter and configured and dimensioned for insertion through a channel of an ureteroscope. The wire is advanceable distal of a distal opening in the channel of the ureteroscope for visualization of the wire. An exchange sheath shields at least a portion of the first wire, and the first wire is slidable with respect to the exchange sheath so the penetrating tip is movable from a retracted shielded position to an exposed unshielded position, the first wire being fully separable and removable from the sheath. The exchange sheath is configured and dimensioned to receive a second wire having a second diameter different, e.g. larger, than the diameter of the first wire to enable wire exchange without removal of the exchange sheath. 
     In preferred embodiments, the wire is lockingly engageable with the exchange sheath and the sheath is lockingly engageable with the ureteroscope. In some embodiments, the exchange sheath is lockingly engageable with the ureteroscope. The wire can include one or more markers to indicate the extent of distal movement relative to the sheath. 
     In some embodiments, the second wire is a guidewire having a diameter of between about 0.020 inches and about 0.038 inches, the first wire has a length of about 90 cm to about 165 centimeters and the sheath has a length of about 80 cm to about 110 centimeters. 
     In another aspect of the present invention, a system is provided for accessing a select calyx for kidney surgery comprising a wire having a penetrating tip and a first diameter and configured and dimensioned for insertion through an ureteroscope. The wire is advanceable distal of the distal portion of the ureteroscope for visualization of the wire. A sheath shields at least a portion of the wire. The wire is slidable with respect to the sheath so the penetrating tip is movable from a retracted shielded position to an exposed unshielded position, the wire fully separable and removable from the sheath. The system includes a mechanism for mounting the sheath to the ureteroscope. 
     In some embodiments, the sheath is removable from the working channel of the scope with the wire remaining within the working channel. 
     In some embodiments, the wire is removable from the sheath leaving the sheath within the working channel of the ureteroscope. 
     In some embodiments, the sheath mounting mechanism includes a locking member with a clamping member to apply a clamping force on the sheath. In some embodiments, rotational movement of a control constricts an opening in the clamping member. The wire can include one or more markers to indicate the extent of distal movement relative to the sheath. The system can include a locking mechanism for releasably locking the wire to the sheath. 
     In some embodiments, the sheath is about a 3 Fr sheath and can have a length exceeding about 90 centimeters. The sheath can have a radiopaque tip. 
     The system can further comprise a coaxial dilator and a sheath. 
     In yet another aspect, the present invention provides a device for retrograde access to and advancement through the calyx and antegrade access to the bladder, the device comprising a wire having a tissue penetrating tip and a sheath encasing the tip, the wire having a length in the range of about 135 cm to about 160 cm to enable insertion through a working channel of a ureteroscope and advancement through a flank of a patient, and a sheath having a length in the range of about 80 cm to about 120 cm to enable locking engagement with the ureteroscope while enabling exit through the distal end of a ureteroscope and through the flank of the patient. 
     The device may further include a marker(s) on the wire to indicate the extent of advancement of the wire. The device may include a first locking mechanism for locking the puncture wire and sheath and a second locking mechanism for locking the sheath and the ureteroscope. 
     The present invention in another aspect provides a kit comprising a) a puncture wire having a first diameter and a first sheath having a first length, the puncture wire slidable with respect to the first sheath, and the sheath removable from the puncture wire; and b) a second sheath having a second length greater than the first length of the first sheath, the second sheath slidable over the puncture wire and dimensioned to receive a second wire having a second diameter greater than the first diameter. 
     In some embodiments the second wire has a diameter of about 0.035 inches to about 0.038 inches and the first wire has a diameter of about 0.017 inches. In some embodiments, the first sheath has a length of about 85 cm to about 120 cm, the second sheath has a length of about 100 cm to about 115 cm and/or the puncture wire has a length of about 90 cm to about 165 cm. 
     Alternate embodiments allow for a larger caliber and variable property puncture wire. It may be possible to pass the dilation balloon directly over the puncture wire, obviating the need for an exchange catheter and second wire. Examples of variable property puncture wires include, but are not limited to, creating puncture wire with coating and/or large caliber for entire length, or excluding the distal puncture region. Coating of portion of wire exposed to body may also reduce risk of injury to tissues. Another wire design may be a coaxial design with inner core of puncture wire, with outer portion of wire of larger caliber, and less injurious to tissue. Outer body of wire may be coil design, and may or may not continue to sharp tip of puncture wire i.e. variable along length of wire. This embodiment describes a dual function wire serving as both puncture instrument and working wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiment(s) of the present disclosure are described herein with reference to the drawings wherein: 
         FIG. 1  is a perspective view of a first embodiment of the puncture wire and sheath of the present invention; 
         FIG. 1A  is a perspective view of an alternate embodiment of the puncture wire and sheath of the present invention; 
         FIG. 2  is a side view illustrating the pin vise lock for locking the sheath and puncture wire together; 
         FIG. 3  illustrates initial insertion of the puncture wire and sheath of  FIG. 1  through a working channel of a flexible ureteroscope positioned through the ureter and extending into the kidney, for clarity the ureteral access sheath not shown; 
         FIG. 4  illustrates the ureteroscope inserted through a selected calyx and the sheath and puncture wire being advanced through the ureteroscope; 
         FIG. 5  is a view similar to  FIG. 4  showing a portion of the ureteroscope of  FIG. 1  and showing further insertion of the puncture wire and sheath through the ureteroscope with the sheath and puncture wire extending distal of the ureteroscope; 
         FIG. 5A  is a view similar to  FIG. 5  illustrating the puncture wire advanced through the flank and skin; 
         FIG. 6  is a view similar to  FIG. 3  corresponding to the position of the puncture wire and sheath of  FIG. 5A  with the sheath locked to the ureteroscope; 
         FIG. 7  is a view similar to  FIG. 5A  illustrating the puncture wire further extended through the skin and the sheath advanced over the puncture wire through the flank and skin; 
         FIG. 8  is a close up view of the sheath locking mechanism; 
         FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 8 ; 
         FIG. 10  is a view similar to  FIG. 7  illustrating withdrawal of the puncture wire from the sheath; 
         FIG. 11  is a view similar to  FIG. 10  illustrating insertion of a guidewire through the sheath; 
         FIG. 12  is a perspective view of one embodiment of a kit of the present invention; 
         FIG. 13  is a perspective view of an alternate embodiment of the puncture wire and sheath of the present invention; 
         FIG. 14  is a cross-sectional view taken along line  17 - 17  of  FIG. 14  showing the pin vise lock clamping the puncture wire; 
         FIG. 15  illustrates initial insertion of the puncture wire and sheath of  FIG. 13  through a flexible ureteroscope positioned through the ureter and extending into the kidney; 
         FIG. 16  illustrates the ureteroscope inserted through a selected calyx and the sheath and puncture wire of  FIG. 13  being inserted through the ureteroscope; 
         FIG. 17  is a cross-sectional view taken along line  17 - 17  of  FIG. 13  illustrating release of the pin vise lock to allow movement of the puncture wire within the sheath; 
         FIG. 18  is a view similar to  FIG. 15  illustrating the puncture wire advanced through the flank and skin; 
         FIG. 19  is a view similar to  FIG. 16  illustrating further advancement of the puncture wire from the sheath; 
         FIG. 20  is a view similar to  FIG. 19  illustrating the puncture wire within the ureteroscope after withdrawal of the sheath from the ureteroscope and patient&#39;s body; 
         FIG. 21  is a view similar to  FIG. 20  illustrating insertion of a second wire through the sheath after a second longer sheath has been advanced over the puncture wire through the flank and skin and the puncture wire and ureteroscope have been removed from the body; 
         FIG. 22  is a perspective view of another embodiment of a kit of the present invention; 
         FIG. 23  is a side view of an alternate embodiment of the puncture wire shown extending through the skin; 
         FIG. 24A  is a side view of an alternate embodiment of the protective sheath; and 
         FIGS. 24B and 24C  illustrate the sheath of  FIG. 24A  exposed different distances from the ureteroscope. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now in detail to the drawings wherein like reference numerals identify similar or like components throughout the several views,  FIGS. 1-22  illustrate various embodiments of the present invention. The present invention provides accessing as well as selecting a calyx under direct visualization utilizing an ureteroscope in order to create a nephrostomy tract for nephrostomy tube creation. 
     A puncture wire is advanced through a working channel of an ureteroscope which has been passed into the kidney in retrograde fashion. The puncture wire is then deployed from the ureteroscope working channel through a surgeon selected calyx and through the kidney and out the flank and skin in a retrograde fashion. This technique obviates the need for antegrade access to the calyx as antegrade access disadvantageously requires significant technical skill due to advancement into the “unknown calyx” and creates potential risks for the patient including relatively high radiation exposure. This retrograde visualization approach of the present invention, as will become apparent from the detailed description below, not only provides improved visualization, but provides such improved visualization while securing/locking the positions of the sheath and wire with respect to the ureteroscope and ensuring the wire is protected from damaging tissue during the procedure. Further, the present invention, as also discussed below, enables a streamlined approach to breaking an obstructing stone with laser and gaining access to the desired calyx which might otherwise be blocked and access denied. 
     Two systems and methods are provided by the present invention, both utilizing a puncture wire and a protective sheath such as 3Fr radiopaque PTFE sheath. In the first system described herein, the sheath which protects the puncture wire during insertion is also used as an exchange sheath so that the puncture wire can be withdrawn and a guidewire inserted into the sheath. This simplifies the components and procedural steps of the surgery. In the second system described herein, two sheaths are utilized: a first protective sheath to protect the puncture wire during insertion and a second sheath to replace the first protective sheath so that the puncture wire can be withdrawn and a guidewire inserted through the second sheath. Both these systems and methods of using the system are described in detail below. 
     Turning initially to the first system and method which is illustrated in  FIGS. 1-13 , the system includes a protective sheath  20  and a puncture wire  30 . Sheath  20  has a lumen  22  extending therethrough dimensioned to slidingly receive the puncture wire  30  therein. That is, puncture wire  30  is received within the sheath lumen  22  for sliding movement from a retracted position wherein the puncture (penetrating) tip  32  of wire  30  is protected (shielded) by the sheath  20  (see e.g.  FIG. 4 ) and an extended position where the puncture tip  32  is exposed from the sheath  20  to penetrate tissue (see e.g.  FIG. 5 ) as the puncture tip  32  extends beyond the distal opening of the sheath  20 . Exposure of the puncture wire tip  32  enables advancement of the wire  30  through the flank and skin as described below. 
     The puncture wire  30  and sheath  20  are releasably locked together by a conventional vise lock  50 . As shown, with reference to  FIGS. 1 and 2 , vise lock  50  has a rotatable actuator  52  and a metal locking tube  54  with a longitudinally extending elongated slot  55 . A first (distal) portion  54   a  of locking tube  54  is seated within tube  56 ; a second opposite proximal portion  54   b  is seated within the actuator  52  ( FIG. 2 ). Actuator  52  has reduced diameter portion  52   a  threadingly received in tube  56  and a lumen  57  through which the wire  30  extends. When actuator  52  is rotated within tube  56 , it clamps down on the metal locking tube  54  reducing its diameter due to the slot  55 , to thereby clamp down on the wire  30  to lock it from sliding movement with respect to the sheath  20 . Consequently, as described below with respect to the method of use, the wire  30  and sheath  20  can be locked together so they can be advanced as a unit through the ureteroscope. When it is desired to move the puncture wire  30  relative to the sheath  20 , the actuator  52  is unscrewed from tube  56 , thereby releasing the clamping force on the metal tube  54  so the wire  30  can slide relative to the sheath  20 . A reinforcement tube  58  extends distally from distal tube  59  which can connect via screw threads (or by other methods). 
     The region of the sheath  20  adjacent the vise lock can include a strengthened region to help stabilize the system. The strengthening can be achieved by thickening, reinforcing or hardening the sheath in this region (see e.g. reinforcement tube  27  of  FIG. 3 ). This would reduce the movement of the pin vise during puncture wire deployment. That is, once this strengthened region is passed into the channel, the Tuohy-Borst type port adaptor and port are tightened, the pin-vise lock above (proximal) this level will be more stabilized. 
     The system also includes a sheath locking mechanism  60  (see e.g.  FIGS. 3 ,  8  and  9 ) for locking the sheath  20  to a working channel of the ureteroscope  40 . This is described in more detail below. 
     A conventional ureteroscope is designated generally by reference numeral  40  in  FIGS. 3-6  and includes a working (operating) channel opening  46  communicating with channel (lumen)  42 . The ureteroscope  40  is preferably a steerable scope so it can be articulated through the urinary system to gain access to the desired calyx. More specifically, the working channel  42  is accessible through an opening in side arm or port  44  which communicates with the ureteroscope channel  42  extending longitudinally within the length of the ureteroscope  40 . The ureteroscope  40  provides both illumination and visualization of the surgical site as well as illumination and visualization of the puncture wire  30  and sheath  20  as they are advanced from the distal opening  47  of the ureteroscope  40 , thus providing visualization of the system components as well as the patient&#39;s body. The ureteroscope  40  typically has a working channel length of about 60 cm to about 66 cm plus a portion of working channel length within the handle of ureteroscope of about 12 cm to about 16 cm (total working channel length about 75 cm to about 82 cm), a total outer diameter at the tip of about 5 French to about 8.1 French, with a working channel diameter of about 3 French to about 4.5 French. The working channel  42  is also dimensioned to receive a laser fiber for reducing blocking stones as described below. The ureteroscope is preferably inserted through a ureteral access sheath (not shown). 
     Note the port  64  of the scope  40  prevents irrigation fluid leakage from the working (operating) channel, and preferably can include a Tuohy-Borst type adapter which seals around instrumentation (e.g. the sheath) inserted therethrough. It can also tighten around the protective sheath with a circumferentially tightening O-ring mechanism. 
     Sheath locking mechanism  60 , as shown in  FIG. 3 , is mounted to side port  44  of ureteroscope  40 . With reference to  FIGS. 8 and 9 , sheath locking mechanism  60  includes a scope mounting portion  62  having a tubular extension at its distal portion for insertion into the working channel  42  of the ureteroscope  40 . The distal portion can have a threaded end for threading into the opening  46  of the working channel  42  or alternatively can be snap fit into opening  46  to attach the mounting portion  62  to the ureteroscope  40 . A lumen extends though the mounting portion  62  and contains a flexible O-ring  68  positioned therein. The sheath  20  extends though the lumen and through the opening in the O-ring  68 . When threaded locking knob  64  is rotated, it provides a clamping force on the threaded cylinder  66  which clamps down on the O-ring  68  to reduce the size of its opening, thereby clamping down on the sheath  20  to lock it into position, i.e. lock it against movement with respect to the ureteroscope  40 . Note the clamping force is sufficient to secure the sheath  20 , but limited to not lock the wire  30  positioned therein, thereby still enabling sliding movement of the wire  30  with respect to the sheath  20 . This locking of the sheath  20  to the ureteroscope  40  advantageously enables the sheath position to be maintained while the surgeon manipulates the puncture wire  30 , as described in more detail below in conjunction with the method. 
     It should be appreciated that the sheath locking mechanism  60  can be provided on the sheath  20  as packaged, or alternatively provided as a separate component. If provided as a separate component, it can optionally be packaged with the sheath  20  in a kit. 
     It should be appreciated that other mechanisms for locking the sheath  20  to the ureteroscope  40  are also contemplated which would retain the sheath position during surgery. For example, the puncture wire/sheath duo could mate and lock directly onto the ureteroscope working channel port either by prior removal of the nipple and directly locking the Luer lock end of the pin-vise apparatus to the working channel, or by locking the pin-vise apparatus onto a separate device that interfaces with the working channel port and puncture wire/sheath duo. 
     Note the portion of the protective sheath  20  nearest the pin vise lock  50  may be made stiffer so that when locked in position by clamp  64 , there would be less motion of the pin vise mechanism during deployment of the puncture wire  30  by the surgeon. One way to achieve this is shown in  FIG. 1A  where tube  69  is positioned over the sheath  20 . 
     The sheath  20  preferably has a length of between about 70 cm to about 120 cm, and more preferably about 100 to about 115 cm. With this length, the sheath  20  has sufficient length for insertion through the entire working channel  42  of the ureteroscope  40 , which typically has a length of approximately 75 cm including the portion of channel within the ureteroscope handle, as well as sufficient length to exit therefrom and extend through the flank and skin. The sheath is preferably a 3 French sheath, having an internal diameter that is sufficient to receive both the puncture wire  30 , and a subsequent 0.025 to 0.038 inch guidewire through the lumen  22 . Other dimensions are also contemplated such as sheath diameters of between about 0.038 inches and about 0.052 inches. The sheath is preferably composed of PTFE (e.g. polyimide or similar), although other materials are also contemplated. 
     The puncture wire  30  preferably has a length of between about 110 cm to about 165 cm, and more preferably a length of about 145 cm. The wire  30  preferably has a diameter ranging from about 0.013 inches to about 0.025 inches, and preferably a diameter of about 0.017 inches, sized to enable sliding movement within sheath lumen  22 . With this length, the puncture wire  30  has sufficient length for insertion through the entire working channel  42  of the ureteroscope  40  as well as sufficient length to exit therefrom and extend through the flank and skin. The puncture wire can be composed of stainless steel, although other materials are also contemplated. 
     Note that other wire lengths are also contemplated. 
     The puncture wire  30  in some embodiments has one or more markings on its outer surface to indicate to the surgeon its position with respect to the sheath  20 , skin, and/or ureteroscope  40 . The markings can be placed on a region of the puncture wire  30  extending outside the body or alternatively or additionally on a region extending within the body to be imaged by the ureteroscope  40 . Likewise, the sheath  20  can have one or more markings on a region outside the body, e.g. adjacent sheath locking mechanism  60 , or adjacent the pin-vise lock, and/or inside the body where the marking(s) can be visualized by the ureteroscope  40 .  FIG. 1A  illustrates markings  39  on a distal portion of wire  30  and markings  29  on a distal portion of sheath  20  by way of example. 
       FIG. 12  illustrates one embodiment of a kit containing the system of the embodiment of  FIGS. 1-12 . In this embodiment, kit  70  includes packaging  72  with portions to receive the puncture wire  30 /sheath  20  assembly as well as a space to receive a guidewire. The guidewire  75  replaces the puncture wire  30  during the procedure as will be described in the method of use below. The kit  70  of  FIG. 12  can also include a sheath locking mechanism such as sheath locking mechanism  60  described above, mounted to the protective sheath  20 , to enable mounting of the sheath  20  to the ureteroscope  40 , or provided as a separate component within the kit  70  which the user would mount to the sheath  20  after removing it from the packaging. 
     Turning now to the method of use of the system of  FIGS. 1-11 ,  FIG. 3  illustrates ureteroscope  40  inserted through the ureter U and extending up to the kidney K. The ureteroscope  40  is manipulated under vision so its distal end  45  extends into the calyx of choice, e.g. calyx C 1  ( FIG. 4 ). Note the ureteroscope  40  can be articulated into the calyx of choice. 
     If during insertion of the ureteroscope  40  a stone is encountered under visualization that is blocking the path to the desired calyx C, e.g. calyx C 1 , C 2 , C 3  etc., a laser fiber (not shown) can be inserted through the working channel  42  of the already positioned ureteroscope  40  to perform laser lithotripsy to reduce the size of the stone to allow access by the ureteroscope  40  to the desired calyx. The laser fiber can then be removed from the working channel  42 . 
     After placement of the ureteroscope  40  at the desired location, e.g. into calyx C 1  of  FIG. 4 , the puncture wire  30  and sheath  20 , locked together by tightening of the pin vise lock mechanism  50  as described above, are inserted through the working channel  42  of ureteroscope  40 . This initial insertion is illustrated in  FIGS. 3 and 4 . At this point, the puncture wire tip  32  of puncture wire  30  is retracted and thereby shielded within the protective sheath  20 . Note the sheath locking mechanism  60  is mounted to side port  44  e.g. via threaded or snap fit engagement, so the sheath  20  can be later locked to the ureteroscope  40 . Sheath  20  extends through the lumen in the locking mechanism  60 . 
     The puncture wire  30  and sheath  20  are then advanced just distal of the tip  45  of the ureteroscope  40  (beyond distal opening  47 ), and viewed to make sure they are in the desired anatomical position. Once so positioned, the threaded knob  64  of sheath locking mechanism  60  is rotated (see arrow of  FIG. 8 ) to clamp down on the O-ring  68  to reduce its lumen internal diameter, thereby providing a clamping force on the outer wall of sheath  20 . This locks the sheath  20  in position, preventing movement with respect to the ureteroscope  40  and easing advancement of the puncture wire for the surgeon. 
     To next advance the puncture wire  30  further through the scope  40  and sheath  20 , actuator  52  of pin vise lock  50  is rotated as described above, thereby releasing the locking engagement of the puncture wire  30  and sheath  20 . This enables the surgeon to advance the puncture wire  30  through the kidney K, flank F and skin S as shown in  FIGS. 5 ,  5 A and  6 . 
     Once positioned through the flank F and skin S, the sheath  20  is then re-locked in relation to the puncture wire  30  and the two components are advanced further through the working channel  42  of the ureteroscope  40  and through the flank and skin to the position of  FIG. 7 . Note the puncture wire  30  has been further advanced from its extended position of  FIG. 6 . 
     It should be appreciated that alternatively the sheath  30  and puncture wire  20  can be locked together by the pin vise locking mechanism  50 , with the puncture tip  32  slightly protruding from the sheath  20 , and advanced together through the skin rather than the puncture wire  30  advanced first, followed by advancement of the sheath  20  over the wire  30  as in the steps of  FIGS. 6 and 7 . In either case, the puncture wire  30  and sheath  20  are advanced through the skin to the position of  FIG. 7 . Note that the puncture wire  30  is protected along its length by the sheath  20  as well as by the ureteroscope  40 . 
     In the next step, illustrated in  FIG. 10 , the puncture wire  30  is withdrawn from the sheath  20  in the direction of the arrow which is opposite the direction of insertion of the wire  30  and sheath  20 , and out through the working channel  42  and side port  44  of the ureteroscope  40 . Note that if the sheath  20  and puncture wire  30  are locked together at this point, the pin vise lock  50  needs to be loosened to allow withdrawal of the puncture wire  30  from the sheath  20 . Withdrawing the wire  30  from the patient&#39;s body leaves the sheath  20  in place extending through the selected calyx C 1  and flank and skin. The ureteroscope  40  is then withdrawn from the body, leaving the sheath  20  in the body, the in situ/in vivo sheath  20  thereby providing a “through and through sheath” as shown in  FIG. 11 . 
     A guidewire  75  can then be inserted though the lumen of the sheath  30 . The guidewire can be inserted in either a retrograde or an antegrade fashion. Guidewires that can be inserted through the sheath  20  include about 0.020 to about 0.038 inch guidewires. After insertion of the wire  75 , the sheath  20  is removed, enabling the wire  75  to obtain “through and through” control of the urinary system. 
     Thus, as can be appreciated, the protective sheath  20  functions as an “exchange sheath” (or exchange catheter) as after withdrawal of the puncture wire  30  therefrom, it allows for passage of another wire e.g. a 0.020 to 0.038 inch guidewire, the guidewire exchange allowing for subsequent passage of various treatment devices thereover, such as a dilation balloon. That is, the guidewire allows for nephrostomy tract dilation. 
     The protective sheath  20 , as noted above preferably has an outer diameter of about 0.042 inches. However, in alternate embodiments, a larger diameter sheath can be utilized which would exchange for larger diameter wires, allowing for subsequent passage of larger diameter devices. 
     An alternate embodiment of the system and method of the present invention is illustrated in  FIGS. 13-21 . In this embodiment, the system includes a sheath  110  and puncture wire  120 . The system also includes a second sheath  130 . 
     More specifically, protective sheath  110  has a lumen  112  extending therethrough dimensioned to slidingly receive the puncture wire  120  therein. That is, wire  120  is received within the sheath lumen  112  for sliding movement from a retracted position wherein the puncture (penetrating) tip  122  of wire  120  is protected (shielded) by the sheath  110  (see e.g.  FIG. 16 ) and an extended position where the puncture tip  122  is exposed from the sheath  110  to penetrate tissue (see e.g.  FIG. 18 ). Exposure of the puncture wire  120  enables advancement of the wire  120  through the flank and skin as described below. 
     The puncture wire  120  and sheath  110  are releasably locked together by a conventional vise lock  150 . The pin vise lock  150  functions like the pin vise lock  50  of  FIG. 2 , and is best illustrated in  FIGS. 14 and 17 . That is, like pin vise lock  50 , pin vise lock  150  has a rotatable actuator  152  and a metal locking tube  154  with a longitudinally extending elongated slot  155 . A first (distal) portion  154   a  of locking tube  154  is seated within tube  156 ; a second opposite proximal portion  154   b  is seated within the actuator  152 . Actuator  152  has a reduced diameter portion  152   a  threadingly received in tube  156  and a lumen through which the wire  120  extends. When actuator  152  is rotated within tube  156 , it clamps down on the metal locking tube  154  reducing its diameter due to slot  155 , to thereby clamp down on the wire  120  to lock it from sliding movement with respect to the sheath  110 . That is, as described below with respect to the method of use, the wire  120  and sheath  110  can be locked together so they can be advanced as a unit through the ureteroscope  40 . When it is desired to move the puncture wire  120  relative to the sheath  110 , the actuator  152  is unscrewed from tube  156 , thereby releasing the clamping force on the metal tube  154  so the wire  120  can slide relative to the sheath  110 . A reinforcement tube  158  extends distally from tube  159  which connects to tube  156  via screw threads. 
     The distal portion of tube  159  can include a threaded region which can be threaded directly into the working channel  42  of ureteroscope  40 . Alternatively, a snap fit arrangement can be provided to attach the pin vise lock mechanism to the working channel  42 . Other methods are also contemplated to attach the locking mechanism  150  to the ureteroscope  40  to thereby lock the sheath  110  to the ureteroscope  40 . 
     The puncture wire  120  of  FIG. 13  may have a length shorter than the length of the puncture wire  30  of  FIG. 1 . For example, the puncture wire  120  preferably has a length of about 135 cm to about 160 cm and can be less than about 145 cm. The sheath  110  of  FIG. 13  has a length shorter than the length of the sheath  20  of  FIG. 1 . For example, the sheath  110  preferably has a length of about 75 cm to about 90 cm and more preferably a length of about 80 cm. Other lengths of the sheath  110  and wire  120  are also contemplated. 
     The system of the embodiment of  FIGS. 13-21  also includes a second sheath  130  designed to replace the first sheath  110  during the procedure. Second sheath  130  preferably has a length of about 85 cm to about 120 cm and more preferably a length of about 100 cm to about 115 cm, an inner diameter of about 0.025 to about 0.045 inches, more preferably from about 0.025 to about 0.038 inches, and an outer diameter of about 0.035 inches to about 0.045 inches, and preferably about 0.042 inches. Other dimensions are also contemplated. As will be explained in further detail below during the discussion of the method, after the sheath  110 /puncture wire  120  assembly are inserted through the ureteroscope  40  and through the flank and skin, the first sheath  110  is withdrawn from the body and the second sheath  130  is inserted through the ureteroscope  40 , advanced beyond the distal end of the scope  40  under visualization, locked to puncture wire with a pin vise lock on second sheath and the puncture wire/sheath duo are further advanced through the flank and skin. Note the pin vise is not shown in the drawings on the second sheath  130 , it being understood that a pin vise similar to the pin vise of the first sheath can be utilized. Other locking mechanisms can also be utilized. Thus, the puncture wire  120 , while being protected within the working channel  42  of the ureteroscope  40 , provides a guide for sheath exchange. Note sheath  130  can in some embodiments include a pin vise lock e.g. (similar to mechanism  150 ) or other locking mechanisms to mount (lock) to the ureteroscope  40 . 
     In some embodiments, a kit is provided containing both sheaths  110 ,  130 . More specifically, as shown in  FIG. 22 , the kit  160  includes a packaging  165  containing the first sheath  110  and the second sheath  130  for replacing the first sheath  110 . Second sheath  130  can include lock  140  to lock to the working channel  42  of the ureteroscope to prevent movement of the sheath  130  with respect to ureteroscope  40 . For example, lock  140  can include a threaded or snap fit attachment mechanism. 
     Turning now to the method of insertion of the system of  FIGS. 13-21 , and with initial reference to  FIG. 15 , the ureteroscope  40  is advanced though the ureter and to the kidney K, and its distal tip  45  is inserted into the calyx of choice, e.g. calyx C 1 , in the same manner as described above with the embodiment of  FIGS. 1-13 . Note that if during insertion of the ureteroscope  40  a stone is encountered under visualization that is blocking the path to the desired calyx C, a laser fiber (not shown) can be inserted through the working channel  42  of the already positioned ureteroscope  40  to perform laser lithrotripsy to reduce the size of the stone to allow access by the ureteroscope  40  to the desired calyx. This is performed in the same manner as described above in the  FIG. 1  embodiment. 
     The puncture wire  120  and protective sheath  110 , locked together by the pin vise lock  150 , are then inserted through the side arm  44  and working channel  42  of the ureteroscope  40  as shown in  FIG. 16 . At this point, the puncture wire tip  122  is retracted within the protective sheath  110 . The sheath  110  and puncture wire  120  are then advanced under visualization just distal of the distal end  45  of the ureteroscope  40 . Once the positioning of the wire  120  and sheath  110  are confirmed by the surgeon, the pin vise lock  150  is loosened ( FIG. 17 ) by rotating actuator  152  in the same manner as described above with respect to pin vise lock  50 , thereby releasing the locking engagement of the puncture wire  120  and sheath  110  and the puncture wire  120  is advanced from the sheath  110  through the kidney K, flank F and skin S to the position shown in  FIGS. 18 and 19 . 
     Note that the threaded distal end or other connecting feature of tube  159  is attached to the working channel  42  to lock the sheath  110  against movement with respect to the ureteroscope  40  once the sheath  110  is advanced slightly distal of the end  45  of the ureteroscope  40 . Other locking mechanisms can also be provided, and positioned on other regions of the sheath, e.g. proximal or distal of pin-vise lock  150 . 
     It should be appreciated that the sheath  110  and puncture wire  120  can be locked together by the pin vise locking mechanism  150 , with the puncture tip  122  slightly protruding from the sheath  110 , and advanced together through the skin or alternatively, the wire  120  can be advanced first, followed by advancement of the sheath  110  over the wire  120 . In either case, the puncture wire  120  and sheath  110  are advanced through the skin. Note that except for the exposed portion beyond the calyx, the wire  120  is protected along its length by the sheath  110  as well as by the ureteroscope  40 . 
     Once positioned through the flank F and skin S, the sheath  110  is then removed from working channel  42  in the direction opposite the direction of insertion of the sheath  110 . This leaves the puncture wire  120  extending through the working channel  42  of the ureteroscope  40 , protected by the ureteroscope  40  as shown in  FIG. 20 . Next, a second sheath  130  is inserted over the puncture wire  40 . The second sheath  130  can be inserted in a retrograde fashion (in the same direction as the first sheath  110 ) over the wire  120  and through the working channel  42  of the ureteroscope  40 , or alternatively, if not provided with an attached vise lock, inserted in an antegrade fashion over the puncture wire  120  and into and through the working channel  42  of the ureteroscope. 
     It is contemplated that if the second sheath  130  does not include a vise lock after antegrade or retrograde insertion, a separate lock can be attached after insertion through the working channel  42  to lock the sheath  130  and puncture wire  120  together and/or lock the sheath  130  to the ureteroscope  40  at the side port  44 . After insertion of the second sheath  130  and advancement out the flank, the puncture wire  130  is removed from the lumen  131  of sheath  130 , preferably in a direction opposite the direction of its initial insertion through the ureteroscope  40 , although it can be removed in the same direction. This leaves the second sheath  130  in position to receive a guidewire therethrough, e.g. guidewire  170  of  FIG. 21 . Guidewire  170  can be inserted in either direction through lumen  131  of sheath  130 . After insertion of the guidewire, the second sheath  130  is removed, leaving the guidewire  170  to extend “through and through.” 
     Note the ureteroscope  40  can be removed after insertion of the second sheath  130  or alternatively after insertion of the guidewire  170  following removal of the puncture wire  120  from sheath  110 . 
     It is also contemplated that in an alternate embodiment, the puncture wire can be utilized without a protective sheath and inserted directly into the ureteroscope  40 . The working channel  42  of the ureteroscope in this embodiment would thereby protect the puncture wire during insertion. This would reduce the number of components. Such sheathless puncture wire would then require subsequent insertion of a sheath thereover to provide access through the flank F and skin S. Such sheathless puncture wire can be utilized with either method disclosed herein or with antegrade passage of the sheath through the flank over the puncture wire. 
     In these sheathless embodiments, the puncture wire can be locked to the operating (working) channel  42  of the ureteroscope  40  during insertion of the ureteroscope  40  into the calyx, and then the puncture wire released from locking engagement with the ureteroscope  40  to enable advancement distal of the end of the ureteroscope through the flank and skin. Such locking can be achieved with a vise lock or a locking mechanism similar to locking mechanism  60  described above, with the O-ring clamping on the puncture wire. Such embodiments enable a larger diameter puncture wire to be utilized, which could enable passage of a dilation balloon or other treatment devices directly over the puncture wire, thereby obviating the need for an exchange catheter and a second wire. 
     It is also contemplated that the characteristics of the puncture wire can be altered. For example, a coating can be applied to improve lubriciousness, and such coating can extend on a portion of or the length of the wire proximal of the tissue puncturing region. Coating with a low friction coefficient material could increase the wire caliber without significantly changing its handling properties. Preferably, the coating would not be applied to the distal 20-30 cm of the wire that is used to puncture the kidney, flank and skin. 
     Also, in some embodiments, portions of the wire can be made thicker, softer or more flexible. For example, the wire can have a thinner portion at the distal portion with a larger diameter at the remaining portion such as the region that contacts and traverses the ureteropelvic junction. This is shown for example in  FIG. 23  where puncture wire  220  has a distal region  221  of a smaller diameter than proximal region  223 . 
     The protective sheath for the puncture wire may be constructed to be thin walled to permit the entire puncture wire/protective sheath duo to maintain a small enough total diameter for passage through the working channel of ureteroscope. Use of materials such as polyimide for sheath construction may have beneficial properties for this application. 
     It should be appreciated that nephrostomy tract dilation could be performed over the puncture wire itself, where the puncture wire may be a single or variable property wire. In this technique, after successful passage of the puncture wire out the flank either with our without the aid of a sheath, the puncture wire is, in fact, not exchanged for a working wire. Rather, the puncture wire itself is suitable for dilation of the nephrostomy tract over the puncture wire. If a variable property puncture wire is utilized, it is possible that a length of wire is further advanced out the flank, and/or a length of wire is removed from a delivered portion of the puncture wire at the flank, such that nephrostomy dilation is performed over a segment of the puncture wire having properties different than the portion of the puncture wire that penetrated the flank/skin. This technique may be utilized with a larger caliber puncture wire, if desired. 
     To enhance functionality of the protective sheath, the distal tip of the protective sheath may be constructed with a gentle bend such as sheath  250  of  FIG. 24A  having a distal bent region  252 . This would provide the urologist with improved ability to direct the path of the puncture wire through the flank. With a Tuohy-Borst style working channel port such as in  FIG. 3  that allows circumferential locking of the outer sheath in relation to the scope, the exact length of the outer sheath that passes out of the ureteroscope tip can be achieved and maintained by the urologist, by engaging the Tuohy-Borst lock around the sheath after passing the sheath out of the end of the ureteroscope  40 . Depending on the length of the outer sheath that is advanced out of the ureteroscope tip, less or more ‘bend’ of the sheath will be exposed, and the path of the puncture wire  260  can thus be better controlled. 
     Thus, as can be appreciated, if less of the sheath  250  is advanced from the end of the ureteroscope  40 , a straighter wire path in relation to the end of the ureteroscope achieved (see  FIG. 24B ). If more of the sheath  250  is delivered, a few degrees of wire deflection will be achieved by virtue of the bend in the end  252  of the sheath  250  (see  FIG. 24C ). One example of how this may be beneficial is the urologist may be able to achieve a more posterior path for wire puncture by extending several millimeters of sheath out of the ureteroscope tip. 
     Precise angulation of the tip of the exposed sheath  250  can be achieved by twisting the pin-vise apparatus with the Tuohy-Borst in a loosened position. With an axial twist-resistant design of the protective sheath, any twist of the pin-vise lock would be reflected in the angulation of the exposed tip of the sheath just beyond the end of the ureteroscope  40 . 
     The sheath may be constructed or post-processed to have enhanced visibility under ultrasound imaging. This may be achieved by any number of techniques, which may include but are not limited to placing a ceramic, graphite, Teflon, tungsten, Nitinol or platinum tip or outer coating on all or part of sheath or creating with or post-processing the sheath using laser or other abrasing or cutting technology to create small or microscopic grooves or indentatons/dimples in the outer surface of the sheath to increase echogenicity. 
     It is also contemplated that all or part of the puncture wire and/or the exchange wire may be designed to have enhanced ultrasound visibility. This may allow for reduced radiation exposure during nephrostomy creation by allowing ultrasound guided confirmation of wire location during deployment. Options to achieve this include, but are not limited to the following: 1) Constructing the puncture wire and/or the exchange wire entirely of, or with a component of, a highly ultrasound-visible metal or other material. Examples include, but are not limited to, cobalt/chromium, graphite, Teflon, platinum or tungsten. These components may be mixed with stainless steel as an alloy or simply the distal tip of the wire can be made of these materials. 2) Coating the puncture wire and/or exchange wire with ceramic material, graphite, Teflon, tungsten, platinum, other metals or polymers, or material impregnated with microbubble technology such as glass microspheres, air microbubbles, or other adherent echogenic polymeric films. 3) The puncture wire and/or exchange wire may be constructed with or post-processed to create uneven surface(s) such as by brushing, lasering, creating indentations or cutting the outer surface of the wire. This would increase echogenicity of the wire. 
     While the above description contains many specifics, those specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the disclosure as defined by the claims appended hereto.