Abstract:
A pair of removable soft pliant plugs is inserted in the Vas to impede the flow of sperm to provide reversible male contraception.

Description:
This is a continuation in part of application Ser. No. 09/718,550, filed Nov. 22, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to male contraception and more generally to devices and methods for reversibly occluding the vas deferens of a male. 
     BACKGROUND OF THE INVENTION 
     Sterilization is the most popular method of contraception in the United States among couples with children and no desire for more children. It is believed that the acceptance of male contraception would improve if the procedure were more likely to be reversible. At present the surgical reversal of a vasectomy is problematic and requires microsurgery. 
     Various techniques have been applied to occlude the vas to achieve reversible contraception. For example, exterior clips have been used to “squeeze off” the lumen of the vas. However, it has been found that the pressure levels required for reliable occlusion promotes tissue necrosis. Injectable plugs have been used to “fill” the vas. However the delivery of the filler material is difficult and the curing time lengthens the procedure time. These “formed-in-place” plugs have also proved prone to migration which is undesirable. 
     The use of an inserted plug for vas occlusion is known from U.S. Pat. No. 4,512,342. The patent disclosed a pair of plugs, which are inserted through two closely, placed incisions in the vas. The plugs are tethered together and a portion of the tether is external to the vas lumen. The plugs are inserted with the aid of a stylus. 
     Published literature describes the evolution of the device and both single and double plugs were explored during development. Various anchor techniques and “no anchors” were tried. This design process resulted in the product described in the patent. Although the device is safe and effective there is a continuing need to improve both the implanted device and the methods and apparatus used to implant the device. 
     SUMMARY 
     According to the preferred methods of the invention, a pair of plugs called intra vas devices (IVD) are inserted through one or two holes in the vas. Each IVD has a hollow tubular body with a blunt and sealed end. A delivery device is provided to stretch the plug to both extend its length and to reduce its diameter. Although it is difficult to quantify, it is important to note that the IVD is very stretchable and flexible. A mandrel like core or stylus called a “stylet” extends through the IVD to engage the blunt end of the IVD. A release feature on the stylet device allows the physician to release the tension on the IVD plug to deploy the plug once it is positioned in the vas. One version of the stylet delivery device has a set of spring loaded jaws which engage the IVD plug at its proximal end. The release feature releases the jaws so the plug may assume a “relaxed” shape in the vas. Another version of the device uses tension on tether to stretch the IVD. 
     A sizer/dilator is used to both dilate the vas and to measure the internal diameter of the vas. Although this sizer step is optional it is preferred as an aid to selecting the correct diameter of plug. In operation, the optimal procedure sequence is to exteriorize the vas using a conventional surgical approach. Then, while holding the vas outside the scrotum a small puncture, incision or “nick” is made in the vas to create a surgical opening. Next the size/dilator is introduced to measure and dilate the lumen of the vas. With this information at hand the physician can select the appropriately sized IVD to load onto a stylet delivery device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Through the several views of the drawing illustrative versions of the devices are shown. In the drawing identical reference numerals indicate identical structures wherein: 
     FIG. 1 is a cross section of an IVD; 
     FIG. 2 is a cross section of an IVD; 
     FIG. 3 is a cross section of an IVD; 
     FIG. 4 is a cross section of an IVD; 
     FIG. 5 is a cross section of an illustrative IVD delivery device 
     FIG. 6 is a cross section of an illustrative IVD delivery device; 
     FIG. 7 is a cross section of an alternate IVD delivery device; 
     FIG. 8 is a cross section of an alternate IVD delivery device; 
     FIG. 9 is a schematic view of a step in a process; 
     FIG. 10 is a schematic view of a step in a process; 
     FIG. 11 is a schematic view of a step in a process; 
     FIG. 12 is a schematic view of the completed procedure; 
     FIG. 13 is a schematic view of a step in a process; 
     FIG. 14 is a schematic of a cross section of an IVD; and, 
     FIG. 15 is a schematic of a cross section of an IVD. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows an exemplary vas occlusion plug or IVD that forms a part of the invention. The IVD plug  10  is hollow as indicated by interior lumen  12 . The IVD is made from a soft pliant biocompatible material such as a low durometer, high elongation silicone rubber. High elongation silicone rubber with durometer measure of  30  has been effective in experiments and in clinical trials. The IVD  10  is formed with a closed and blunt distal end  14 . The proximal end  9  is open. When the IVD is molded and in its unstretched state it has a characteristic length L 1  and a characteristic diameter D 1  which are labeled in the figure. In general the IVD will be offered in various sizes (D 1 ) and lengths (L 1 ) with up to six representative sizes presently contemplated as; 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm and 2.0 mm. 
     FIG. 2 shows the IVD of FIG. 1 stretched to its insertion length L 2  which corresponds to a diameter reduction to a dimension shown as D 2  in the figure. To maximize the reduction in diameter for a given amount of stretch a material with a high Poisson ratio is desirable. The IVD is stretched by the application of traction between the interior distal tip and the proximal outer surface. The force is applied to the distal tip through insertion of a stylet  16  that forms a part of the delivery device. This stylet  16  should be blunt. This bluntness is accentuated in the figure by the ball end  18  forming the distal tip of the stylet 16 . 
     FIG. 3 shows an externally “ribbed” IVD  13  that has an optional metalic coating  15  of copper or other spermicidal material. The bulk material is silicone rubber and mirrors the construction of the IVD  10 . However the ribs typified by rib  19  increase the path length of the IVD so that sperm is less likely to travel over the entire length of the IVD and the sperm that does pass over the IVD has greater contact with the metal layer. It is also anticipated that the ribbed portion may allow for a broader range of fit of IVD to the vas and prevent migration of the IVD within the vas. 
     In FIG. 15 internal ribs are shown as typified by rib  17 . Ribs in this location running the length of the interior lumen assist in releasing the IVD from the stylet. It may be convenient to extrude the IVD as a tube and then seal the end. This manufacturing technique is an alternative to molding the IVD as a single piece. 
     FIG. 4 shows an IVD with a metallic coil  21  of copper or other metallic material encircling the outer portion of the IVD  23  device. The scale of the wire is exaggerated to show the preferred helical form. The helical form allows the IVD to stretch longitudinally. In general copper is known to be an effective spermacide when placed in the vas. The amount of metal must be predetermined to remain intact during the service life of the implanted IVD. It is generally know that metals have spermicidal attributes. The actual mechanisms for interfering with sperm are not well understood. It is believed that the placement of copper on the exterior of the IVD will result in a low toxicity highly effective male contraceptive. 
     FIG. 5 shows a schematic cross section of a delivery device, which can be used to stretch the IVD into the operable position. The delivery device  20  has a spring  22  which supplies a force between a collar  24  and a collet closer member  26 . In operation the tapered surface of the collet jaws  30  abuts and engages the tapered surface  32  of the collar  24 . In this figure, a hand not seen, is forcing the spring  22  into compression by moving the collar  24  toward delivery device  20 . In use the collar  24  forms a handle portion for the manipulation of the device. In use the physician will stretch the IVD toward the collet jaws  30  and release the handle to capture the proximal end surface of the IVD in the jaws. Or in the alternative the stylet  16  may be moved relative to the collet closer  26  by releasing the setscrew  17 . In this mode the user would insert the proximal end of the IVD into the collet and allow the spring  22  to close the jaws around the IVD. Next the user would push the sytlet  6  into the IVD stretching it to the required length. Next the setscrew can be tightened to fix the stylet into the collet closer  26 . This state is depicted in FIG.  6 . 
     FIG. 6 shows an IVD stretched and captured in the delivery device  20 . In this state the spring  22  supplies traction to the IVD between the distal tip and the proximal surface. The amount of stretching is controlled by the length of the stylet  16 . As described above the stylet  16  may be anchored in the collet closer member  26  with a setscrew  17  or the like to allow adjustment of the effective length of the stylet  16 . In general the stylet is flexible yet stiff enough to resist buckling. The IVD and sytlet are easily manipulated by grasping and rotating the delivery device  20 . 
     FIG. 7 is an alternate collet style IVD delivery device with a moveable ring  62  used to hold the collet jaws  64  in the closed position. In this device a setscrew  17  is used to retain and position the stylet  16  the handle  68 . 
     FIG. 8 is a view of the collet style IVD delivery device of FIG. 7 in the “open” position. In this view the ring  62  is forced proximal on the handle  68  to allow the collet to spring into the open position. 
     FIGS. 9,  10  and  11 , should be considered together. They are illustrative of a preferred and illustrative sequence for carrying out the method of the invention. In FIG. 9 the vas  40  is elevated above the scrotum  42  through an incision  44 . A puncture incision  46  is made in the vas which does not completely sever the vas. In FIG. 10 the lumen  50  of the vas  40  is open and the lumen has a dilator/sizer  52  inserted into it. It has been found that the sooth muscle of the vas can contract and the size must be carefully determined to ensure a successful outcome. In FIG. 11 the delivery device  20  is positioned to release an IVD  10  in the lumen  50  vas  40 . The fact that the diameter is reduced permits easier insertion in the vas with less trauma. With the IVD well placed the physician moves the collar  24  relative to the collet closer member  26  to release the IVD from the jaws  30 . This motion is shown in the figure by arrows  70  and  72 . 
     FIG. 12 shows a pair of opposed IVDs  10  and  11  respectively placed in a patient&#39;s vas  40 . IVD  10  shows a suture loop  80  (exaggerated in the drawing for clarity) placed through the IVD  10  to secure it in a fixed location in the vas. IVD  11  has not been sutured but it includes a “tail”  43  seen in the figure as ball tethered to the main body of the IVD. The tail is left outside the vas and it is an optional feature of the IVD. The tail may take any of various forms including buttons or disks or rods. It is not clear which approach is best to prevent migration and both are permissible. IVD migration is not a primary concern if the sizer is used to select a near optimal size device. 
     One distinct advantage of the process and devices set forth above is that they may be surgically removed by reentry into the vas and removal of the IVD plugs. The suture  80  or “tail”  43  permit quick location of the location of the IVD devices. It is expected that the vas will heal with little scarring and the potency of the user returned. This reversibility is a major advantage of the device not shared with more invasive and destructive sterilization techniques. 
     FIG. 13 shows an alternate delivery strategy. This figure is similar to FIG. 11 where a device  10  is being inserted into the lumen  50  of a vas  40 . The scale has been greatly exaggerated to depict the fact the vas is stretching during insertion. This stretching is shown by the bulging of the vas at location  100 . At the same location the device  10  is being reduced in diameter during insertion. It is difficult to quantify the amount of vas stretching required for this method but the objective is to share or allocate the deformation required to fit the device between the device and the vas. It has been determined that this strategy results in a “tight” fit of the plug in the vas. It is anticipated that this amount of “tightness” will not cause tissue necrosis. 
     Device  10  insertion according to FIG. 13 can be accomplished with a stylet  16  alone or with a companion delivery tool which includes a handle  17  and an anchor to hold the device in the stretched condition if desired. The O-ring  19  depicted in the figure is an example of an anchor used to trap the tail  43 . 
     In the alternative, if the device has a tail  43  attached the physician may press the tail or tether against the stylet  16  to hold the IVD in the stretched condition. The hole  47  may pierce the IVD off center or on center. Traction applied to the tether may be used to stretch the device. 
     This process is facilitated by the use of xylocane as a lubricant between the vas lumen  50  and the device  10 . It is expected that other approved lubricants such as silicone or surface treatments on the device will also improve this insertion method. Xylocane is preferred because it is typically approved, available and used as an anesthetic for the procedure. 
     FIG. 14 shows a device  10  optimized for the insertion process. The blunt distal end  14  is slightly tapered rather than the hemispheric tip seen in other embodiments. This taper joins the cylindrical body of the device at location  102 . It is preferred to have the internal lumen terminate distal of location  102 . This shape facilitates deformation of the device  10  by the vas during insertion and also reduces the occurrence of the stylet  16  from puncturing the device and the vas. 
     FIG. 15 shows the relative cross sections of the device diameter D 3  and the interior lumen diameter D 4 . The device appears to work well with a nominal D 3 /D 4  ratio of 1.75. Testing performed with deivces from 1.61 to 1.77 have proved workable. 
     It should be apparent that numerous modifications to the device or delivery tool may be made without departing from the scope of the invention, which is set forth in the claims.