Abstract:
Devices (plugs) for occluding fallopian tubes are disclosed. The plugs, or at least portions thereof, are made of elastomeric silicone or other biocompatible material and include a pilot hole which permits an insertion device to be used to insert the plug into the fallopian tube. The plugs of the present invention allow fallopian tubes to be rapidly occluded for birth control purposes with minimal adverse side effects. The plugs are also adapted to be removed from the fallopian tubes in a relatively simple procedure without adversely affecting the fallopian tubes.

Description:
[0001]    This is a continuation-in-part of International Application No. PCT/US03/06195, filed on Feb. 28, 2003, which is hereby incorporated by reference herein in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to medical devices that are implanted in the human body. In particular, the present invention relates to medical devices that can be used to occlude the female mammalian fallopian tubes.  
           [0004]    2. State of the Art  
           [0005]    It is often desired to close the fallopian tubes of women for birth control purposes. One method for closing the fallopian tubes is surgical tubal ligation, a procedure in which the uterine tubules are tied and cut or clamped through an incision made through the wall of the abdomen. When done endoscopically, the pelvic cavity must be pneumatically inflated. Aside from injury due to possible over-inflation, numerous cases of the formation of embolisms have been reported. Tubal ligation done with a laparotomy requires a surgical incision in the abdomen done under general anesthesia. Aside from permanent scar formation at the site of incision, there are reported cases of death due to anesthesia complications.  
           [0006]    Other methods for female sterilization have been investigated. In one technique, a curable elastomeric composition (such as silicone) is transcervically injected into the fallopian tubes in an amount sufficient to fill the portion of the oviduct adjacent the uterus. The elastomeric composition is allowed to solidify to thereby nonsurgically block the tube. This technique, which is described in U.S. Pat. No. 3,805,767 to Erb, has problems associated therewith. For example, the technique is time consuming and requires a high level of technical skill both for the preparation of the silicone and for performing the procedure.  
           [0007]    Others techniques have been proposed. For example, U.S. Pat. No. 5,601,600 to Ton discloses the placement of an occlusive wire or coil within the fallopian tubes to occlude them. The coil must be delivered into the fallopian tubes with a delivery catheter extending from the uterus into the fallopian tubes. This technique, which is being commercialized by Conceptus, Inc. under the tradename “Essure™”, is problematic because it takes a long period of time (typically on the order of 3 months) for the wire or coil to form fibrous tissue that blocks the fallopian tube.  
           [0008]    U.S. Pat. No. 6,346,102 to Harrington et al. discloses the placement of a releasable heat generating plug within the fallopian tubes. RF energy is supplied to the heat generation plug such that the plug thermally damages the fallopian tube to cause it to constrict around the plug. After such constriction, the plug is released and left in place to occlude the fallopian tubes. The heat generating plug includes electrically conductive electrode(s), an insulator made from thermal and electrically insulating material. In an alternate embodiment, laser light is supplied to the heat generation plug such that the plug thermally damages the fallopian tube to cause it to constrict around the plug. In this embodiment, the heat generating plug includes a cylindrical heating tip made of silicone/bioglass that is loaded with dispersive particles that disperse the laser energy throughout the tip and convert the energy into heat (which thermally damages the fallopian tube to cause it to constrict around the plug). In yet another embodiment, the heat generation plug includes a piezo-electrical crystal. Electrical energy is supplied to the piezo-electrical crystal such that it emits ultrasound energy that heats up the plug and surrounding tissue (which thermally damages the fallopian tube to cause it to constrict around the plug). These devices are problematic in that the thermal damage to the fallopian tubes is difficult to control and, if not controlled properly, may impart inadvertent damage to the surrounding tissue. Moreover, because this technique damages the fallopian tube, reversal of the procedure requires complex microsurgery or may be impossible to accomplish.  
           [0009]    Consequently, there is a need for improved devices that efficiently and effectively occlude the fallopian tubes of women for sterilization purposes with minimal adverse side effects. Preferably, the improved occlusion devices are adapted to be removed from the fallopian tubes without undue adverse effects.  
         SUMMARY OF THE INVENTION  
         [0010]    It is therefore an object of the present invention to provide improved means for occluding the fallopian tubes of a woman for birth control purposes. Occlusion of the tubes prevents male sperm from fertilizing female eggs, thus preventing conception.  
           [0011]    It is a further object of the invention to provide fallopian tube occluding plugs and tools for inserting those plugs into a fallopian tube.  
           [0012]    In accord with the objects of the invention, which will be discussed in more detail hereinafter, fallopian tube occlusion devices (plugs) are disclosed. The plugs, or at least portions thereof, are made of elastomeric silicone or other biocompatible material and include a pilot hole which permits an insertion device to be used to insert the plug into the fallopian tube. The plugs of the present invention allow fallopian tubes to be rapidly occluded. The plugs are also adapted to be removed from the fallopian tubes in a relatively simple procedure without adversely affecting the fallopian tubes.  
           [0013]    Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a partial view of the female reproductive system, showing the occlusion device of the present invention being inserted into a fallopian tube and prior to detachment of the occlusion device (plug).  
         [0015]    [0015]FIG. 2 is a perspective view of an occlusion device inserted into a uterine tube portion in accordance with the present invention.  
         [0016]    [0016]FIG. 3 is a bottom perspective view of the occlusion device of FIG. 2.  
         [0017]    [0017]FIG. 4 is a perspective view of an insertion device in accordance with the present invention.  
         [0018]    [0018]FIG. 5 is an exploded view of the insertion device of FIG. 4. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]    [0019]FIG. 1 shows some of the major elements of the female reproductive system. The uterus  2  is an organ of the female pelvis that has the shape of a pear. It consists of a thick muscular coat  3  (referred to as the myometrium), a cavity  4  having an inner mucosal lining of variable thickness (referred to as the endometrium), and a cavity  5  (referred to as the uterine cavity). The cervix  6  defines the cervical canal  7  which is an inferior opening to the vagina  8 . The fallopian tube  9  is a bilateral duct that connects the uterus  2  to the ovary  10 . The ovary  10  is the organ that produces one or more eggs during every cycle of a woman&#39;s reproductive life. Each fallopian tube  9  can be logically divided into 4 parts:  
         [0020]    i) Infundibulum—the funnel-shaped, expanded lateral end of the tube which overlies the ovary; the free edge has many finger-like processes, the fimbriae, suspended over the ovary; it contains the abdominal ostium of the tube;  
         [0021]    ii) Ampulla—the intermediate segment which is adjacent the infundibulum; it is relatively wide and tortuous;  
         [0022]    iii) Isthmus—the narrow portion that lies just lateral to the uterus; and  
         [0023]    iv) Intramural (interstitial), the uterine portion of the tube; this pierces the uterine wall, and through the uterine ostium.  
         [0024]    The site where the fallopian tube  9  and uterus  2  connect is called the uterotubal junction  11 . It is a section of tubular shape of about 10 mm in length. Its inner diameter in the resting position is less than 1 mm. But when gas or liquid is pushed through the uterus and tubes, the diameter of the uterotubal junction may stretch up to about 2 mm. The uterotubal junction  11  provides a transition between the uterus  2  and the fallopian tube  9 , and the area of transition from the chamber of the uterus to the lumen of the uterotubal junction is referred to as the ostium or cornu. The ostium, uterotubal junction, and the fallopian tube itself are part of a pathway leading from the ovaries to the uterus, and this pathway is sometimes referred to as the uterine tube.  
         [0025]    [0025]FIG. 2 illustrates a uterine tube portion  104  that has been occluded using a plug  102  in accordance with the present invention. Uterine tube portion  104  has a lumen  106  (which is part of the pathway leading from an ovary  10  to the uterus  2 ), and plug  102  has been inserted axially into lumen  106  to occlude the uterine tube portion. Preferably, the external surface  107  of plug  102  is symmetric about an axis  108  as shown. Furthermore, the external surface  107  preferably tapers from a base  109  disposed at one end to a rounded top portion  110  as shown. To facilitate insertion of the plug  102  into uterine tube portion  104 , the cross-sectional diameter of the rounded end  110  is smaller than the diameter of lumen  106 . Moreover, to ensure that the plug  102  remains at its desired position in the uterine tube portion  104 , the cross-sectional diameter of the base  109  is larger (typically on the order of 10 to 35 percent larger and preferably between 25 to 30 percent larger) than the diameter of lumen  106 . The plug  102  also preferably includes spring-biased prongs  208  that extend below the base  109  and radially outward with respect to axis  108  as shown.  
         [0026]    Uterine tube portion  104  has an elastic wall surrounding lumen  106 . The elastic nature of the uterine tube portion  104  allows the plug  102  to be tightly grasped by the uterine tube portion  104 . More specifically, when the plug  102  is inserted into its desired position in the uterine tube portion  104 , the larger diameter base  109  and possibly the spring-biased prongs  208  (which extend radially into the elastic wall of the uterine tube portion  104 ) cause the elastic wall of the uterine tube portion  104  to be deformed such that the plug  102  is tightly grasped by the wall of the uterine tube portion  104  as shown. Therefore, the elastic nature of the walls enables the plug  102  to be effective in occluding uterine tube portion  104 . Furthermore, the elastic walls of uterine tube portion  104  also permit a small range of plugs  102  of varying diameter to be used for different sizes of uterine tube sections  104 . Thus, plug  102  of a certain size may be used for occluding uterine tube sections of different sizes. Typically, plug  102  ranges from 1 mm to 2.5 mm in maximum cross-sectional diameter. When inserted into the lumen  106  of the uterine tube portion  104 , the plug  102  provides total occlusion of the uterine tube portion, thereby preventing male sperm from fertilizing female eggs and thus preventing conception. Preferably, the plug  102  is inserted and positioned at or near the uterotubal junction to provide for total occlusion of the fallopian tube as shown in FIG. 1; however, it is contemplated that the plug  102  can be positioned at many locations inside the uterine tube to provide total occlusion.  
         [0027]    As shown in FIG. 3, the exterior surface  107  of plug  102  is formed by a layer  202  of biocompatible material. Preferably, silicone is used to form layer  202 . Silicone is useful since it is non-toxic, chemically inert, substantially insoluble in blood and substantially non-immunogenic. In addition to silicone, newer elastomeric biocompatible materials may also be used to manufacture the layer  202 . Ongoing research and development in biocompatible materials have created materials with a longer life, better strength and lower cost—all of which are desirable qualities of the material of the exterior surface layer  202 . Typical examples of such materials include polyurethanes and polyisobutylene-based polymers.  
         [0028]    Plug  102  is preferably provided with a frame structure  204  that supports the exterior surface layer  202  such that surface layer  202  withstands the forces acting upon it when the plug  102  is inserted into the uterine tube portion  104 . More specifically, upon inserting the plug  102  into uterine tube portion  104 , the elastic walls of the uterine tube portion exert a compressive force on the exterior surface layer  202 . The frame structure  204  mechanically supports the exterior surface layer  107  to counteract these forces. Preferably, the frame structure is corrugated and includes projections  206  that extend radially inward toward the central axis  108  as shown. These features provide for increased strength of the frame structure  204 . In the exemplary plug shown, the frame structure  204  includes four projections that are spaced  90  degrees apart. The radial width of each projection tapers from a point near the top of the projection to the bottom of the projection as shown. The top of the frame structure  204  mechanically supports a prong structure which includes a plurality of spring-biased (preferably metal) prongs  208  and an integral base  209  which is joined to the prongs by joints  211 . In the exemplary plug shown, the four spring-biased prongs  208  are spaced 90 degrees apart. In addition, the base  209  of the prong structure and the top of the frame structure  204  includes pilot holes  210   a ,  210   b . These pilot holes are sized to receive an insertion device  300  and thereby enable plug  102  to be mounted on an insertion device  300  as described below with respect to FIG. 4. Preferably, the frame structure  204 , including projections  206  and prongs  208 , are made of hard plastic and/or metal (such as titanium) or some other material of sufficient rigidity and strength.  
         [0029]    In an alternative embodiment (not shown) of plug  102  of FIGS. 2 and 3, the plug  102  may be constructed without any prongs  208 . In this embodiment, plug  102  may be manufactured using materials of sufficient structural rigidity and strength. Furthermore, the prongs  208  may be avoided by suitably increasing the thickness of the frame structure  204 .  
         [0030]    In a typical procedure, the plug  102  is inserted into uterine tube portion  104  by substantially aligning the axis  108  of the plug  102  with the longitudinal axis of the uterine tube portion  104 , and by applying a force along the axis  108 . The practitioner may apply this force by using a deployment mechanism such as the insertion device  300  shown in FIG. 4. This insertion device  300  has a casing  302  and a lever  306 . The practitioner uses the lever  306  to operate the insertion device  300 . Lever  306  enables a needle  308 , housed in a tubular needle guard  310 , to be retracted inwards. To insert the plug, the practitioner mounts a plug  102  on the needle  308  of the insertion device (if the plug is not already pre-mounted). This is done by inserting the needle  308  into the pilot holes  210  of the plug  102  such that the distal end  311  of the needle guard butts up against the base  209  of the prong structure. Next, the practitioner inserts the plug/needle guard  310  into the body non-invasively: through the vagina, through the cervix and into the uterine cavity. The practitioner aligns the axis  108  of the plug  102  with the longitudinal axis of the uterine tube portion  104 , and applies an axial force to the insertion device  300 , thereby inserting the needle  308  and the plug  102  mounted thereon to a desired position in uterine tube  104 . As the plug is pushed in the lumen of the uterine tube, the downward angle of the ends of the prongs  208  enables the prongs  208  and plug body ( 107 ,  204 ,  206 ) to slide along the walls of the uterine tube. In addition, the constricting force of the uterine tube compresses the plug body ( 107 ,  204 ,  206 ), which in turn causes the ends of the prongs  208  to be retracted inward with respect to the central axis. In this manner, any damage caused by the prongs  208  to the inner walls of the uterine tube is limited. When force is no longer applied by the practitioner, the prongs  208  spring outwardly and dig into the walls of the uterine tube. The prongs  208  together with the relative diameters of the plug  102  and lumen of the uterine tube  104  enable the elastic walls of the uterine tube  104  to tightly grip and secure the plug  102  as described above. The practitioner then presses button  306  to retract the needle  308  inward such that it is housed in the needle guard  310  and becomes disengaged from the pilot holes  210 , thereby releasing the plug  102  from the insertion device  300 . This procedure can be done under guidance provided by x-ray imaging, sonar imaging, an hysteroscope or blindly.  
         [0031]    [0031]FIG. 5 shows an exploded view of insertion device  300 . This device is essentially a spring activated device. A spring  400  and a needle guide  402  have been shown encased in casing  302 . When the lever  306  is activated, it propels needle guide  402  toward the back end  312 . In turn, this needle guide propels the needle  308  inwards such that it retracts into the distal end  311  of needle guard  310 . Hence, the needle  308  is released from plug  102 . When the lever  306  is not activated, the spring  400  propels needle guide  402  such that it moves away from the back end  312 . In turn, the needle guide propels needle  308  outward such that it is extends from the distal end  311  of guard  310 . It will be apparent to one skilled in the art that alternative ways to propel the needle may be employed by the insertion device  300 . A lock may be added to deactivate the lever  306  and needle guide  402  such that once the lever  306  has been activated to deploy the plug, the needle  308  remains inside and shrouded by the guard  310  to avoid accidental trauma to the patient, practitioner or nurse. As is readily apparent from FIG. 1, the needle guard  310  (and needle  308  housed therein) is preferably malleable such that it can be readily maneuvered and bent (if necessary) prior to and/or during insertion into the uterus.  
         [0032]    The plug device  102  of FIGS. 2 and 3 is designed to provide a permanent occlusion of an uterine tube portion  104 , thereby preventing male sperm from fertilizing female eggs and thus preventing conception. In other words, it generally is not meant to be removed. Such a design is useful as a permanent birth control mechanism. However, in certain circumstances, it may be desirable to provide a mechanism to remove the “permanent” occlusion device. This may be accomplished by pushing on the base  209  of the prong structure  208  (e.g., by inserting a rigid needle/guide structure into pilot holes  210  and pushing with axial force). This will cause the spring-biased prongs  208  to retract radially inward. A relatively rigid sleeve may then be slipped over the retracted prongs so that the prongs  208  do not impale the arterial walls and so that the plug  102  may be pulled from the lumen  106  of the uterine tube portion  104 .  
         [0033]    While the present invention has been discussed above in connection with human sterilization and birth control, it will be apparent to those skilled in the art that it may also be applied in numerous animals for which sterilization/birth control is desired. While particular embodiments of the invention have been illustrated and described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular materials have been disclosed, it will be appreciated that other materials can be used as well. In addition, while particular sizes of plugs have been disclosed, it will be understood that different sized plugs can be used for use in certain blood vessels. Further, while the plugs have been disclosed with reference to relative direction (e.g., top, bottom, front, rear, etc.), it will be understood that these terms are relative terms and not intended to be limiting with respect to the orientation of the plugs in space. In addition, while the plugs have been disclosed as being provided separately from an insertion device, it will be appreciated that the plugs may be pre-mounted on insertion devices, and sets of plugs and insertion devices may be sold as a kit for a particular surgery. Numerous other modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art. It will therefore be appreciated by those skilled in the art that those modifications, changes, variations, substitutions and equivalents could be made to the provided invention without deviating from its spirit and scope as claimed.