Abstract:
A device and a related method for urinary catheterisation is provided. The device comprises a catheter having an elongate body provided with a distal tip, a proximal end and one or more channels extending therethrough. A guidewire for guiding the catheter upon insertion extends through one of said one or more channels. In addition, there is a lubrication port at or towards the proximal end of the elongate body for introduction of a guidewire lubrication fluid into the channel having the guidewire extending therethrough. Also provided is a device and related method for urinary stricture dilatation, as well as kits for urinary catheterisation and urinary stricture dilatation.

Description:
FIELD 
       [0001]    The present invention relates to a device and a related method for urinary catheterisation and urethral stricture dilatation. 
       BACKGROUND 
       [0002]    Catheterisation involves the insertion of a catheter into a body cavity, duct or vessel, thereby allowing drainage or injection of fluids or access by surgical instruments. In the case of urinary catheterisation, a catheter is inserted into a patient&#39;s bladder usually for the treatment of urinary incontinence, or to release urine from the bladder when the patient is in acute urinary retention due to, for example, prostate enlargement or post-operatively to monitor urine output when a patient is ill and unable to move. The catheter is normally inserted through the patient&#39;s urethra, but if the urethra is blocked or damaged the catheter may need to be inserted into the patient&#39;s bladder through the wall of the abdomen instead. 
         [0003]    There are two main types of urinary catheterisation. Indwelling catheterisation means that a catheter is left in the body for a period of time. It should be performed by a medical practitioner. Intermittent catheterisation is the temporary placement of the catheter to empty the patient&#39;s bladder and may be performed by a medical practitioner or by the patient (in which case it is termed intermittent self-catheterisation). 
         [0004]    Catheters for indwelling catheterisation typically have two or three channels and are retained inside the bladder by a balloon located at the tip of the catheter. The balloon is inflated by pumping air, water or saline solution down the narrow balloon channel of the catheter using a syringe. Once inflated, the balloon keeps the catheter securely in the bladder while the primary channel of the catheter allows urinary drainage. An optional third irrigation channel may be used to wash away blood and small clots that may be present after bladder or prostate surgery. This prevents larger clots from forming, which might otherwise block the catheter. 
         [0005]    Catheters for intermittent catheterisation do not have a balloon at the tip because they are not intended to be retained in the bladder. 
         [0006]    Where a patient has a blocked urine flow due to a narrowing of the urethra, known as a urethral stricture, the stricture will often need to be stretched before a catheter can be inserted. Stretching of the stricture can be achieved using a urethral dilator. 
         [0007]    A problem with known types of catheters and dilators, is that correct insertion of the device can be a difficult and potentially harmful procedure due to the natural curvature of the bulbar urethra in men. It can be difficult to advance the catheter/dilator into the part of the urethra known as the prostatic urethra which curves upwards towards the bladder, especially when the prostate is enlarged. The distal tip can cause trauma to the urethral tissue as the user attempts to navigate the catheter along the curved path of the bulbar urethra towards the prostatic urethra. Tissue trauma can lead to the formation of a false passage (i.e. a hole dug into the wall of the urethra), which can make future urethral catheterisation attempts difficult, if not impossible. 
         [0008]    If malposition of the catheter is not noticed, inflation of the catheter balloon whilst the tip of the catheter is still in the urethra (a risk associated with known types of indwelling catheters) can seriously damage the urethral tissue, causing pain, bleeding and traumatic rupture. The rupture can heal with a urethral stricture which may require dilatation or surgery at a later date. At worst, if the urethral tissue damage is not noticed in time, subsequent urethral ischaemic necrosis can result in associated life threatening sepsis and loss of urethral and penile tissue. 
         [0009]    There is a need to improve upon current urinary catheterisation and urethral stricture dilatation devices and methods of insertion in order to improve the safety of the procedures, to simplify and speed up insertion and to improve the performance of the devices. 
       SUMMARY 
       [0010]    In a first aspect, the present invention resides in a device for urinary catheterisation comprising:
       a catheter having an elongate body provided with a distal tip, a proximal end and one or more channels extending therethrough;   a guidewire extending through one of said one or more channels for guiding the catheter upon insertion; and   a lubrication port at or towards the proximal end of the elongate body for introduction of a guidewire lubrication fluid into the channel having the guidewire extending therethrough.       
 
         [0014]    Preferably, the guidewire is provided with a stopper in order to prevent the proximal end of the guidewire from passing through the guidewire channel towards the distal tip of the catheter and becoming lost in the urethra or bladder. The stopper may be adapted to receive a syringe for introducing guidewire lubrication fluid into the guidewire channel when the stopper is coupled to the lubrication port. Lubrication of the guidewire is important since it reduces friction between the guidewire and the urethra and also between the guidewire and the catheter. 
         [0015]    The stopper may take various forms, for example the stopper may comprise a head portion and a body portion arranged in a T-shaped configuration and having a hollow core extending therethrough, with the body portion capable of being received in the lubrication port and the head portion capable of receiving the syringe. Alternatively, the stopper may comprise only a head portion having a hollow core extending therethrough, the head portion capable of receiving the syringe. In each configuration of stopper the head portion may suitably be larger than the opening of the lubrication port. The stopper may be releasably connected to the lubrication port, preferably by a screw means, a push-fit means or a twist-lock means, though other mechanisms such as a snap-lock or a Luer Lock may equally be used. 
         [0016]    Moreover, the stopper may be provided with an anchor for connecting the proximal end of the guidewire to the stopper. The anchor may be suitably configured so as to allow the guidewire lubrication fluid to flow around the anchor as it passes through the stopper and into the guidewire channel. Preferably, the anchor comprises a band, which traverses the width of the hollow core of the stopper, and end members at either end of the band, which are embedded in either side of the body of the stopper to as to secure the anchor in the stopper. More preferably, the anchor may be I-shaped. In a preferred arrangement, the proximal end of the guidewire is connected to the band of the anchor. Suitable means of connection include welding when, for example, the anchor is formed of metal and an epoxy resin when, for example, the anchor comprises a rigid polymeric material. 
         [0017]    Preferably, the catheter further includes a drainage channel separate from the guidewire channel for the drainage of urine. The drainage channel may extend along the centre of the elongate body and the guidewire channel may extend parallel to the drainage channel along one side of the elongate body. Optionally, the guidewire channel may also act as an irrigation channel for the introduction of sterile irrigating solution into the bladder once the guidewire has been removed. 
         [0018]    The lubrication port may comprise a side arm in fluid communication with the guidewire channel adjacent to the proximal end of the catheter. The lubrication port may be provided with a closure member for preventing drainage of urine through the lubrication port when the guidewire has been removed. Preferably, the closure member is a one-way valve. 
         [0019]    Advantageously, the guidewire extends beyond the distal tip of the catheter when the stopper is coupled to the lubrication port. Preferably, the guidewire comprises a hydrophilic polymeric material. 
         [0020]    The distal tip of the catheter may be open-ended so as to allow for drainage of urine from the bladder. Beneficially, this feature may also allow for the catheter to be used with known guidewires for the purpose of changing a long-term urethral catheter, particularly a suprapubic catheter. This makes the catheter changing procedure much safer and easier because the tract of the supra-pubic catheter cannot be lost. This is a frequent issue when inadequately trained clinical practitioners change suprapubic catheters. 
         [0021]    Preferably, the elongate body of the catheter may be provided with at least one further drainage hole adjacent to the distal tip of the catheter so as to increase drainage efficiency. More preferably, the catheter may be provided with two drainage holes, which are located adjacent to the distal tip, one on either side of the catheter, so as to further increase drainage efficiency. Moreover, the presence of three drainage holes means that even if one or two of the holes become blocked, for example with a blood clot, drainage of urine can continue to take place through the other drainage hole. 
         [0022]    The distal tip of the catheter is preferably formed at an oblique angle so as to help reduce tissue trauma as the catheter passes through the urethra. The oblique angle also provides a leading edge which helps the catheter to follow the guidewire in the bulbar and prostatic urethra. 
         [0023]    The catheter may further comprise an inflatable balloon located adjacent to the distal tip of the catheter for retaining the catheter inside the bladder. In order to inflate the balloon, the catheter may include an inflation channel for introducing inflation fluid into the balloon. 
         [0024]    The catheter may typically be made from a flexible, resilient and biocompatible polymeric material, such as polytetrafluoroethene (PTFE), polyethylene, polypropylene, polyurethane, polyvinyl chloride (PVC), latex or silicone. The inflatable balloon can be made from the same material as the catheter and may comprise a fine distensible additional layer of polymeric material attached to the elongate shaft. 
         [0025]    To promote ease of insertion, withdrawal and positioning of the catheter, the catheter may optionally be coated with a hydrophilic lubricious polymer, such as polyurea, polyurethane, polyurethaneurea, polyglycols, polyvinyl pyrrolidone (PVP) or carboxylic acids, esters, salts and amides of poly(meth)acrylic acid, which becomes slippery in the presence of an aqueous fluid. Additionally or alternatively, a tube of lubricant such as Lidocaine/Aquagel or Aquagel alone can be injected into the urethra. To reduce and delay the occurrence of an infection, the catheter may also be coated with an anti-infective material such as a silver alloy or an antibiotic. 
         [0026]    The size of the catheter may typically be between 10 French and 26 French in diameter and between 20 cm and 50 cm in length. A longer length catheter is usually required for males since the male urinary tract is longer than the female urinary tract. 
         [0027]    In a second aspect, the present invention resides in a method of urinary catheterisation, comprising:
       lubricating a guidewire located in a channel extending through a catheter, the catheter having an elongate body provided with a distal tip, a proximal end and one or more channels extending therethrough, and the guidewire having a distal tip and a proximal end;   inserting the distal tip of the guidewire into the urethra and navigating the guidewire along the urethra and into the bladder;   advancing the catheter over the guidewire until the distal tip of the catheter is located in the bladder; and   removing the guidewire from the urethra and the catheter.       
 
         [0032]    In a third aspect, the present invention resides in a device for urethral stricture dilatation comprising:
       a dilator having an elongate body provided with a distal end tapered towards a distal tip, a proximal end and a guidewire channel extending therethrough;   a guidewire extending through the guidewire channel for guiding the dilator upon insertion; and   a lubrication port at the proximal end of the elongate body for introduction of a guidewire lubrication fluid into the guidewire channel.       
 
         [0036]    The distal end of the dilator may taper along a length of between 3 cm and 4 cm towards the distal tip. Furthermore, the distal end of the dilator may be angled relative to the elongate body. Preferably, the distal end may be angled between 30° and 45° relative to the elongate body. Conveniently, the size of the dilator may range between 2-14 French and 2-24 French. 
         [0037]    The dilator may typically be made from a resilient and biocompatible polymeric material so that it can push through the scar tissue of a urethral stricture. The tapered distal end of the dilator may be made from a different material to the remainder of the elongate body. For example, the tapered distal end may be made from a material which provides it with greater flexibility, reduced flexibility, greater slipperiness or reduced slipperiness compared to the remainder of the elongate body. Alternatively, or in addition thereto, the tapered distal end may be made from a material whose physical properties vary depending on the surrounding temperature. For example, the material may be one that distends (swells) upon contact with the patient&#39;s body but contracts upon contact with cold water. To promote ease of insertion, withdrawal and positioning of the dilator, the dilator may optionally be coated with a hydrophilic lubricious polymer, such as polyurea, polyurethane, polyurethaneurea, polyglycols, polyvinyl pyrrolidone (PVP) or carboxylic acids, esters, salts and amides of poly(meth)acrylic acid, which becomes slippery in the presence of an aqueous fluid. Additionally or alternatively, lubricant such as Lidocaine/Aquagel or Aquagel alone can be injected into the urethra. To reduce and delay the occurrence of an infection, the dilator may also be coated with an anti-infective material such as a silver alloy or an antibiotic. 
         [0038]    In a fourth aspect, the present invention resides in a method of urethral stricture dilatation, comprising:
       lubricating a guidewire located in a guidewire channel extending through a dilator, the dilator having an elongate body provided with a distal end, tapered towards a distal tip, and a proximal end, and the guidewire having a distal tip and a proximal end;   inserting the distal tip of the guidewire into the urethra and navigating the guidewire along the urethra and into the bladder;   advancing the dilator over the guidewire until the distal tip of the dilator is located in the bladder; and   removing the guidewire and the dilator from the urethra.       
 
         [0043]    In a fifth aspect, the present invention resides in a guidewire for use in a medical device, wherein the guidewire is provided with a stopper for preventing loss of the guidewire. Preferably, the stopper is adapted to receive a syringe for introducing guidewire lubrication fluid onto the guidewire. 
         [0044]    Advantageously, the catheter and dilator of the present invention may be used with known guidewires, for example, those comprising a core wire coated with hydrophilic polymer. 
         [0045]    In a sixth aspect, the present invention resides in a urinary catheterisation kit comprising:
       a catheter having an elongate body provided with a distal tip, a proximal end and one or more channels extending therethrough;   a guidewire extending through one of said one or more channels for guiding the catheter upon insertion;   a lubrication port at or towards the proximal end of the elongate body for introduction of a guidewire lubrication fluid into the channel having the guidewire extending therethrough; and   a sterile package in which the catheter and guidewire are supplied for use, the package adapted to be opened to allow injection of guidewire lubrication fluid through the lubrication port to lubricate the guidewire in the channel having the guidewire extending therethrough and that portion of the guidewire extending beyond the distal tip of the catheter.       
 
         [0050]    The kit may further comprise an external sterile package for housing the sterile package containing the catheter and guidewire, wherein the external sterile package additionally houses at least one syringe. Preferably, the at least one syringe is pre-filled with guidewire lubrication fluid. 
         [0051]    In a seventh aspect, the present invention resides in a urethral stricture dilatation kit comprising:
       a dilator having an elongate body provided with a distal end tapered towards a distal tip, a proximal end and a guidewire channel extending therethrough;   a guidewire extending through the guidewire channel for guiding the dilator upon insertion;   a lubrication port at the proximal end of the elongate body for introduction of a guidewire lubrication fluid into the guidewire channel; and   a sterile package in which the dilator and guidewire are supplied for use, the package adapted to be opened to allow injection of guidewire lubrication fluid through the lubrication port to lubricate the guidewire in the guidewire channel and that portion of the guidewire extending beyond the distal tip of the dilator.       
 
         [0056]    The kit may further comprise an external sterile package for housing the sterile package containing the dilator and guidewire, wherein the external sterile package additionally houses a syringe. Preferably, the syringe is pre-filled with guidewire lubrication fluid. 
         [0057]    The present invention has the advantage of simplifying and improving the safety of the catheterisation/dilatation procedure. The integration of the guidewire into the catheter/dilator facilitates placement of the catheter/dilator in the urethra and provides a convenient and safe product for use by a medical/clinical practitioner or patient. 
         [0058]    The guidewire of the present invention is especially advantageous because the stopper prevents loss of the proximal end of the guidewire along the guidewire channel into the urethra or bladder. Moreover, when the stopper is capable of receiving a syringe filled with lubrication fluid, it enables the hydrophilic guidewire to be lubricated whilst it is located within the catheter/dilator. This helps to maintain the sterility of the device whilst it is prepared for use and makes preparation more convenient for the user. Also, the fact that the device is still retained inside its internal wrapping at the time of lubrication ensures that the guidewire is fully lubricated along its entire length. 
         [0059]    A number of definitions are provided that will assist in the understanding of the invention. 
         [0060]    The term ‘catheter’ as used herein denotes a hollow tube used to drain fluid from a body cavity, duct or vessel, or to distend a body passage, and the term ‘catheterisation’ denotes the operation of introducing a catheter into the body. 
         [0061]    The term ‘dilator’ as used herein denotes an instrument for dilating or distending a body cavity, duct, vessel, canal or orifices, and the term ‘dilatation’ as used herein denotes the operation of introducing a dilator into the body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0062]    In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which: 
           [0063]      FIG. 1  is a device for urinary catheterisation in a first embodiment of the present invention: (a) is a side view of an indwelling catheter having a drainage channel, a balloon inflation channel and a guidewire channel with guidewire in-situ; (b) is a cross-sectional view of the catheter taken along the line II-II; (c) is a cross-sectional view of the catheter taken along the line III-III. 
           [0064]      FIG. 2  is a guidewire having a stopper for use in all embodiments of the present invention: (a) is a perspective view of a guidewire having a T-shaped stopper; (b) is a perspective view of a guidewire having a cylindrical stopper; (c) is an end view of the stopper as shown in (a) and (b). 
           [0065]      FIG. 3  is a side view of a device for urinary catheterisation in a second embodiment of the present invention. 
           [0066]      FIG. 4  is a side view of a device for urethral stricture dilatation in a third embodiment of the present invention. 
           [0067]      FIG. 5  is a top view of the sterile packaging for a device of all embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0068]    A first embodiment of the invention is shown in  FIG. 1 . The device comprises a catheter  10  having a flexible elongate shaft  12 . The elongate shaft  12  defines a drainage channel  14  which extends along the length of the catheter  10  from the distal tip  16  of the catheter  10  to the proximal end  18  of the catheter  10 . The proximal end  18  of the catheter  10  is capable of being connected to a fluid collector (not shown). 
         [0069]    The distal tip  16  of the catheter is open-ended and formed at an oblique angle. The open end of the distal tip  16  defines a drainage hole  20 , which allows fluid to enter the drainage channel  14 . Two further drainage holes  22  are located adjacent to the distal tip  16 , one on each side of the elongate shaft  12 , to increase drainage efficiency of the device. 
         [0070]    An inflatable balloon  24  is located adjacent to the distal tip  16  of the catheter  10  and encircles the elongate shaft  12 . Typically, the balloon  24  has a maximum volume of between 10 ml and 30 ml and is spherical in shape, although various shapes may be used. The wall of the elongate shaft  12  houses an inflation channel  26 , which extends along the length of the catheter  10  from the inflatable balloon  24  to an inflation channel side arm  28  positioned adjacent to the proximal end  18  of the catheter  10 . The inflation channel  26  is cylindrical and typically has a diameter between 0.1 mm and 0.3 mm. The inflation channel side arm  28  houses a two-way valve  30  and is capable of receiving a syringe. The balloon  24  is inflated by inserting a syringe (not shown) filled with air, water or saline solution into the inflation channel side arm  28  and injecting the contents of the syringe into the inflation channel side arm  28 , through the valve  30 , and along the inflation channel  26  until the balloon  24  is sufficiently expanded. The valve  30  prevents the contents of the inflated balloon  24  from leaking out of the inflation channel side arm  28  until deflation is required. To deflate the balloon  24 , an empty syringe is connected to the inflation channel side arm  28  and the contents of the balloon  24  are removed by suction. 
         [0071]    The wall of the elongate shaft  12  further comprises a guidewire channel  32 , which extends along the length of the catheter  10  from the distal tip  16  of the catheter  10  to a guidewire channel side arm  34  positioned adjacent to the proximal end  18  of the catheter  10  on the opposite side of the shaft to the inflation channel side arm  28 . The guidewire channel  32  is oblong in cross-section although other shapes may be used, for example, oval, circular, or square in cross-section, and typically has dimensions of about 1-2 mm×1 mm. Both the guidewire channel  32  and the inflation channel  26  run parallel to the drainage channel  14  and are independent from the drainage channel  14 . The guidewire channel side arm  34  has a one-way valve  36  to prevent urine from draining along the guidewire channel  32  and out of the opening  44  of the guidewire channel  32  when the guidewire  38  has been removed from the device. Alternative means of closing the guidewire channel  32  may be used. 
         [0072]    A flexible guidewire  38  is located in the guidewire channel  32  and serves to guide the catheter  10  into the correct position upon insertion. The guidewire  38  is typically between 0.8 mm and 0.9 mm in diameter and between 100 cm and 180 cm in length, and extends from the proximal end of the guidewire channel side arm  34 , along the full length of the guidewire channel  32  and beyond the distal tip  16  of the catheter  10 . 
         [0073]    The guidewire  38  comprises a core wire, typically made of stainless steel, platinum, shape memory alloys such as Nitinol, or other metal, which provides a degree of stiffness to the guidewire  38 . The core wire extends almost the entire length of the guidewire  38 , terminating shortly before the guidewire distal tip  40 , and may taper in diameter towards the distal tip  40 , thereby increasing the flexibility of the guidewire  38  towards the distal tip  40 . The highly flexible distal tip  40 , without the core wire, is typically between 3 cm and 9 cm in length. The flexibility of the distal tip  40  reduces tissue damage and degradation as the guidewire  38  enters the body and enables the user to safely and easily manoeuvre and navigate the guidewire  38  along the urinary tract towards the bladder. 
         [0074]    The core wire of the guidewire  38  is coated with a hydrophilic polymer, such as polyurea, polyurethane, polyurethaneurea, polyglycols, polyvinyl pyrrolidone (PVP) or carboxylic acids, esters, salts and amides of poly(meth)acrylic acid. The hydrophilic coating becomes slippery in the presence of an aqueous fluid, such as water, and provides surface lubricity to the guidewire  38 . This surface lubricity reduces friction between the guidewire  38  and body tissue as the guidewire  38  passes through the urinary tract and also reduces friction between the guidewire  38  and the guidewire channel  32  as the catheter  10  is passed over the guidewire  38 . 
         [0075]    The hydrophilic coating can comprise a simple coating of one polymer, a blending/complexing of two or more hydrophilic polymers, an interpenetrating network of polymers or one or more chemically reactive hydrophilic polymers. 
         [0076]    A stopper  50  located at the proximal end  42  of the guidewire  38  prevents the guidewire  38  from disappearing along the guidewire channel  32  towards the distal tip  16  of the catheter  10  and becoming lost in the urethra or bladder. 
         [0077]      FIGS. 2(   a ) and  2 ( b ) show two different stopper designs in more detail.  FIG. 2(   a ) shows a stopper  50  having a T-shaped configuration and comprising a hollow core  52  which extends through the body  54  and the head  56  of the stopper  50 . The head  56  of the stopper  50  contains a narrow metal anchor  58  which traverses the hollow core  52  and is embedded in either side of the head  56  of the stopper  50 . The proximal end  42  of the guidewire  38  is welded to the metal anchor  58 , thereby securely connecting the guidewire  38  to the stopper  50 . 
         [0078]    The head  56  of the stopper  50  is capable of receiving a syringe (not shown), with the nose of the syringe fitting into the hollow core  52  of the stopper  50 . To lubricate the guidewire  38 , a syringe filled with aqueous fluid, such as water, is inserted into the head  56  of the stopper  50  and the fluid is injected into the stopper  50 , through the guidewire channel side arm  34  and along the guidewire channel  32  towards the distal tip  16  of the catheter  10 . The narrow width of the metal anchor  58  in the head  56  of the stopper  50  means that fluid can easily move past the anchor  58  as it passes through the stopper  50 . 
         [0079]    The body  54  of the stopper  50  is sized so as to be able to fit into the guidewire channel side arm  34 , whilst the head  56  of the stopper  50  is larger than the opening  44  of the guidewire channel  32  and abuts the opening  44  so as to prevent the stopper  50  from passing through the guidewire channel  32  towards the distal tip  16  of the catheter  10 . The stopper  50  is releasably connected to the guidewire channel side arm  34  by means of a screw thread  60  on the outer surface of the body  54  of the stopper  50  which interacts with a complimentary screw thread on the inner surface of the guidewire channel  32  to provide a secure connection between the guidewire  38  and the catheter  10  prior to and during use of the guidewire  38 . 
         [0080]    An alternative configuration of stopper is shown in  FIG. 2(   b ). In this instance, the stopper  50  comprises only a head  56  having a hollow core  52  into which the nose of a syringe fits. The head  56  of the stopper  50  is connected to the proximal end  42  of the guidewire  38  by means of an anchor  58 , as previously described, and abuts the opening  44  of the guidewire channel  32  to prevent the stopper  50  from passing through the guidewire channel  32  towards the distal tip  16  of the catheter  10 . To enable a secure connection between the stopper  50  and the catheter  10 , the head  56  of the stopper  50  can be releasably coupled to the guidewire channel side arm  34  as previously described with reference to  FIG. 2(   a ).  FIG. 2(   c ) shows an end view of the stopper  50  of  FIGS. 2(   a ) and  2 ( b ) and the configuration of the anchor  58  traversing the hollow width  52  of the stopper  50 . 
         [0081]    In use, the device of a first embodiment of the invention, as shown in  FIG. 1 , is inserted into the patient&#39;s urinary tract and retained in the bladder to drain away urine in the following manner. 
         [0082]    Firstly, the full length of guidewire  38  is lubricated by inserting a syringe filled with water into the stopper  50  located at the proximal end  42  of the guidewire  38  and injecting the contents of the syringe into the stopper  50 , along the guidewire channel side arm  34  and along the full length of the guidewire channel  32 . Upon contact with the water, the hydrophilic coating of the guidewire  38  swells and becomes slippery and provides surface lubricity to the guidewire  38 . The surface lubricity helps to reduce friction between the guidewire  38 , the guidewire channel  32  and body tissue as the guidewire  38  passes through the urinary tract. Once the guidewire  38  is fully lubricated, it is then ready to be inserted into the urethra of the patient. 
         [0083]    A lubricant is inserted into the urethra of the patient, then the tip  40  of the guidewire  38  is inserted into the urethra and the guidewire  38  is navigated along the path of the urethra towards the bladder. The high flexibility of the guidewire tip  40  reduces tissue damage and degradation as the guidewire  38  moves along the urinary tract and helps the user to circumvent any obstructions in the urethra. By inserting the entire length of the guidewire  38  the user can be sure that the guidewire  38  has reached the bladder. The presence of the stopper  50  prevents the guidewire  38  from disappearing along the guidewire channel  32 . 
         [0084]    Once the guidewire  38  is fully inserted into the bladder, the catheter  10  is ready to be advanced over the guidewire  38 . The surface lubricity of the guidewire  38 , combined with the optional surface lubricity of the catheter  10 , reduces the frictional resistance between the guidewire  38  and the guidewire channel  32  as the catheter  10  slides over the guidewire  38 . The guidewire  38  defines the path along which the catheter  10  travels and makes catheter insertion much safer and more reliable, thereby causing minimal discomfort to the patient. 
         [0085]    The catheter  10  is in its fully inserted position when the distal tip  16  of the catheter  10  reaches the bladder and the balloon  24  is beyond the bladder neck. The user can assess whether or not the end of the catheter  10  is correctly positioned in the bladder by observing the drainage of urine through the drainage channel  14  of the catheter  10 . If no urine drainage is observed, the distal tip  16  of the catheter  10  is still in the urethra and the catheter  10  will need to be advanced further along the guidewire  38 . Once urine drainage is observed, the user can be sure that the catheter  10  is in the correct position and the guidewire  38  can safely be removed from the bladder and the catheter  10 . The catheter  10  is then connected at its proximal end  18  to a fluid collector (not shown). 
         [0086]    To retain the catheter  10  in the bladder, the balloon  24  is inflated by inserting a syringe filled with water or saline solution into the inflation channel side arm  28  and injecting the contents of the syringe into the inflation channel side arm  28  and along the inflation channel  26  until the balloon  24  is filled. The catheter  10  remains in place until the patient is able to void again after surgical treatment, until measurement of urine output is no longer required or until the catheter  10  needs to be replaced. To remove the catheter  10 , the balloon  24  is deflated by connecting an empty syringe to the inflation channel side arm  28  and sucking the water or saline solution out of the balloon  24 , and then the catheter  10  is carefully removed. 
         [0087]    The guidewire channel  32  can optionally be used as an irrigation channel, once the catheter  10  has been fully inserted and the guidewire  38  removed, to flush sterile irrigating solution into the bladder. In this instance, an irrigation fluid connector (not shown) is attached to the guidewire channel side arm  34  using a releasable connection mechanism such as a screw fit, a push-fit, a snap-lock, a twist-lock or a Luer Lock. Once the bladder has been suitably irrigated and cleared of blood clots etc., the irrigation fluid connector is removed. 
         [0088]    A second embodiment of the invention is shown in  FIG. 3 . This device is intended for patients who require intermittent catheterisation in order to empty their bladder because of bladder failure or after bladder reconstruction. The device does not need to be retained in the bladder so it does not have an inflatable balloon but it is otherwise identical to the first embodiment of the invention. In this instance, the catheter  10  is inserted into the patient&#39;s bladder and retained there only until complete drainage of urine from the bladder has been observed. 
         [0089]    A third embodiment of the invention is shown in  FIG. 4 . This device is for dilating urethral strictures and comprises a dilator  70  having an elongate shaft  72 . The elongate shaft  72  defines a guidewire channel  74  which extends along the length of the dilator  70  from the distal tip  76  of the dilator  70  to the proximal end  78  of the dilator  70 . The guidewire channel  74  is cylindrical and typically has a diameter between 0.8 mm and 1.0 mm, although it tapers at the distal end  76  of the elongate shaft  72  towards the distal tip  76 . Both the distal tip  76  and the proximal end  78  of the guidewire channel  74  are open-ended and the proximal end  78  is provided with a handle  80  for ease of use. 
         [0090]    A flexible guidewire  38  is located in the guidewire channel  74  and serves to guide the dilator  70  into the correct position upon insertion. The guidewire  38  and stopper  50  of this embodiment of the invention is identical to that used in the first and second embodiment of the invention. As per the previous embodiments, the stopper  50  located at the proximal end  42  of the guidewire  38  prevents the guidewire  38  from disappearing along the guidewire channel  74 , except in this embodiment there is no guidewire channel side arm so the stopper  50  interacts with the proximal end  78  of the dilator  70  rather than the proximal end of the guidewire channel side arm. 
         [0091]    The size of the dilator  70  is typically between 2-14 French and 2-24 French in diameter and between 30 cm and 40 cm in length. The distal end  77  of the dilator  70  is curved at an angle of approximately 30-45° to help follow the natural curve of the urethra, although straight tips may also be used. Moreover, the distal end  77  is tapered over a length of approximately 4 cm towards the distal tip  76  from a diameter of between 14 French and 24 French at the widest point of the elongate shaft  72  down to 2 French at the distal tip  76 . The dilator  70  also has circumferential markings (not shown) every 10 cm along the length of the elongate shaft  72  in order to assist the medical/clinical practitioner in assessing the length of dilator  70  that has been inserted into the urethra. The close fit of the distal tip  76  around the guidewire  38  helps to prevent urethral tissue from becoming caught between the distal tip  76  and the guidewire  38  and therefore reduces the likelihood of tissue damage. Furthermore, the tapered distal end  77  and the narrow diameter of the distal tip  76  causes the distal end  77  of the dilator to be more flexible than the remainder of the wider elongate shaft  72 . 
         [0092]    The relatively long tapered distal end  77  of the dilator  70  of the present invention compared to known dilators allows for a large increase in diameter in a single dilator. This enables the user to dilate the stricture up to the maximum width required using a single dilator rather than having to use multiple dilators each having a slightly increased diameter (e.g. 6/10 F, 8/12 F, 12/14 F, 14/18 F, etc. whereby the first number denotes the calibre of the tip and the second number denotes the calibre of the shaft). Using one dilator safely over a guidewire speeds up the dilatation procedure and reduces the number of dilators normally used to treat a urethral stricture and hence the amount of waste material produced. 
         [0093]    In use, the device of the invention, as shown in  FIG. 4  is inserted into the patient&#39;s urinary tract to dilate a urethral stricture in the following manner. 
         [0094]    Firstly, the full length of the guidewire  38  is lubricated and fully inserted into the urethra as per the first and second embodiment of the invention. The highly flexible tip  40  of the guidewire  38  helps the user to find the lumen of the urethral stricture. Once the guidewire  38  has been advanced into the bladder, the dilator  70  is ready to be advanced over the guidewire  38 . The dilator  70  is inserted until the distal tip  76  reaches the bladder thereby stretching the stricture to the calibre of the dilator shaft. The dilator  70  and the guidewire  38  are then removed from the urethra. 
         [0095]      FIG. 5  shows how the device of the invention is packaged in a sterile environment ready for use. This packaging can be used for all the embodiments of the invention, i.e. an indwelling catheter ( FIG. 1 ), an intermittent catheter ( FIG. 3 ) or a dilator ( FIG. 4 ), having an integral guidewire  38 . The packaging enables the device to be prepared for use in a convenient and sterile manner. 
         [0096]    The device of the invention (not shown) is contained within a sterile internal wrapping  90 , which is typically made from plastic. The internal wrapping  90  has a top side and a bottom side (not shown) and is substantially rectangular in shape for ease of manufacture, though other shapes are equally suitable. A first perforation  92  is located at the proximal end  94  of the internal wrapping  90 , which is where the proximal end of the device is situated. A second perforation  96  is located at the distal end  98  of the internal wrapping  90 , which is where the distal tip of the device is situated. Both the first and second perforations extend across the full width of the top and bottom side of the internal wrapping  90 , enabling the internal wrapping  90  to be completely torn at these positions. A third perforation  100  extends along the top side of the internal wrapping  90  from the distal end  98  to approximately the mid-point  102  of the wrapping  90 . 
         [0097]    The internal wrapping  90  is housed within a sterile external wrapping  104 , which is typically made of plastic or paper. The external wrapping  104  has a top side, a bottom side (not shown) and is substantially rectangular in shape, and comprises a peelable corner  106  at its proximal end. Additionally housed within the external wrapping  104  is a syringe  108  pre-filled with water for lubricating the guidewire  38 . Where the device comprises an indwelling catheter  10  with an integral guidewire  38 , the external wrapping  104  houses two syringes filled with water; one for lubricating the guidewire and one for inflating the balloon. Alternatively, the syringes within the external wrapping  104  may be empty and can be filled by the user when the device is ready to be used. 
         [0098]    The device of the invention is prepared for use in the following manner. First, the external wrapping  104  is opened by pulling at the peelable corner  106  at the proximal end of the wrapping. The contents of the external wrapping  104 , which include the internal wrapping  90  containing the device and at least one syringe  108  filled with water, are then transferred onto a sterile surface, such as a table or the internal sterile side of the external wrapping. 
         [0099]    Next, the first perforation at the proximal end  92  of the internal wrapping  92  is torn to expose the proximal end of the device. The syringe  108  filled with water is then inserted into the stopper  50  located at the proximal end of the guidewire  38  of the device and the water is injected through the stopper  50  in order to lubricate the guidewire  38 . The entire length of the guidewire  38  becomes lubricated by virtue of the fact that it is curled up within the internal wrapping  90  and becomes immersed in the water. 
         [0100]    Once the guidewire  38  has been fully lubricated, the second and third perforations  96 ,  100  of the internal wrapping  90  are torn to expose the distal tip of the device. The internal wrapping  90  can then be discarded or it can be kept in position until after the guidewire  38  has been inserted in order to further protect the catheter/dilator. 
         [0101]    Although particular embodiments of the invention have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims. It is contemplated by the inventor that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims.