Abstract:
A contraceptive device for transcervical reversible cornual sterilization includes an implant portion configured for implanting into the patient&#39;s uterine myometrium at a uterine cornu and circumscribing the fallopian tube&#39;s opening and a cap portion removably connected to the implant portion. The cap portion has an impermeable membrane substantially impermeable to the passage of reproductive cells, wherein when the implant portion is implanted into the uterine myometrium near the fallopian tube opening circumscribing the fallopian tube opening, the cap portion occludes the fallopian tube.

Description:
CROSS-REFERENCE TO RELATED CASES 
       [0001]    This is a U.S. non-provisional application of U.S. provisional patent application Ser. No. 60/875,615 filed on Dec. 18, 2006, the entire disclosure of which is incorporated herein by reference 
     
    
     FIELD OF THE INVENTION 
       [0002]    This disclosure relates to apparatus and method for providing permanent yet easily reversible sterilization of the human female by transcervical reversible cornual sterilization. 
       BACKGROUND 
       [0003]    Human sterilization refers to any procedure by which a person is rendered incapable of reproduction. Worldwide, two well tried and tested forms exist currently, tubal sterilization for women and vasectomy for men. Both forms are intended to be permanent and irreversible. Permanent tubal sterilization (or transabdominal tubal interruption) is currently the most common method of effective long-term contraception chosen by couples on a worldwide basis. 
         [0004]    In the 1970&#39;s, the popularity of tubal sterilization and thus the number of surgical procedures performed increased dramatically in Europe, China, India, other parts of Asia and Latin America. In the United States, the number of tubal sterilization increased nearly fourfold—from approx. 200,000 in 1970 to about 700,000 in 1977. This increase was largely the result of development of two new surgical approaches, namely minilaparotomy and laparoscopy. These superceded the previous method of the 1920&#39;s to the 1950&#39;s of post partum laparotomy with the Pomeroy method of tubal occlusion. 
         [0005]    In the United States in 1970 less than 1% of sterilizations were performed with a laparoscope, but by 1975, more than one third of the 550,000 women who had tubal sterilization had the procedure performed this way. The approach was facilitated in the early 1970&#39;s by the use of safe electro coagulation to permanently interrupt the tubal lumen, followed later in that decade by the development of spring loaded clips and Silastic rings for the same purpose. 
         [0006]    In 1990 about 191 million married women of reproductive age used permanent sterilization (of themselves or of their spouses by vasectomy) for contraception. 169 million of these were in the developing countries and 22 million in developed countries. World-wide the ratio of female to male sterilization is 3 to 1. In the United States, sterilization is also the most commonly used form of contraception among married couples. The proportion of married couples who used tubal sterilization increased from 9% in 1973 to 28% in 1995. The increase in male sterilization (vasectomy) was much less dramatic, rising from 8% in 1973 to 11% in 1995. 
         [0007]    The cumulative failure rate at 5 years for laparoscopic tubal sterilization in a major US study of procedures performed in the mid 1980&#39;s is quoted at 1 in 150. The likelihood of such a pregnancy being ectopic is extremely high. About 61% of the total when pregnancy occurs in the 4 th  to 10 th  years after tubal sterilization. The fatality rate associated with transabdominal tubal sterilization is in the order of 1 in 25,000. The most frequent serious immediate complications for laparoscopic tubal sterilization are associated with abdominal entry. These include bowel and major vessel injury in particular. For example in a study conducted in the United Kingdom, major vessel injury occurred in nine of 10,000 laparoscopies. 
         [0008]    Modern hysteroscopy was introduced in the early 1970&#39;s as a method of visualizing the uterine cavity and uterotubal junctions. The idea of occluding this area by hysteroscopy was revived with considerable interest along with this developing technology. Examples of various transcervical and mainly hysteroscopic techniques used in the last 30+ years in an attempt to occlude the intramural portion of the fallopian tubes (interstitial oviducts) are: electrocoagulation and cryocoagulation; injection of chemicals into the uterine cavity for permanent closure; non-destructive occlusion by plastic preformed plugs; mechanical devices or tubal plugs that are placed in the proximal portion of the interstitial oviduct; and intratubal devices. 
         [0009]    To date no successful, safe and efficient method of transcervical reversible tubal sterilization has been developed. The first and the only device approved (2002) by the United States Food and Drug Administration that is currently in use amongst the populus at the time of this patent application for permanent transcervical tubal sterilization, is the Essure System produced and marketed by the Conceptus corporation. It consists of a micro-insert, to obliterate the interstitial oviduct, a disposable delivery system, and a disposable split introducer. Because it is a transcervical tubal sterilization, the Essure System avoids the incision and the need for general anesthesia associated with transabdominal methods. However, this method again is not reversible. 
         [0010]    By far the most common serious long-term risk associated with all forms of permanent sterilization, whether transabdominal or transcervical interruption of the fallopian tube lumen or vasectomy, is the patient&#39;s regret that this irreversible procedure was performed. In general, post sterilization regret increases over time. In the US Collaborative Review of Sterilization, the cumulative probability of regret went from 4% overall at 3 years to 13% at 14 years. At least five studies have identified young age at sterilization as the strongest predictor of later regret of sterilization. In the above study, the cumulative probability of expressing regret within 14 years was 20% for woman 30 years or younger versus 6% for those older than 30 years. Likewise, the 14 year cumulative probability of requesting information about reversal was 40% among women sterilized at 18 to 24 years compared to 10% for women over 30 years. Thus, a safe trsnscervical method of sterilization that is easily reversible is desired. 
       SUMMARY 
       [0011]    According to an embodiment, a contraceptive device for transcervical reversible cornual sterilization is disclosed. The contraceptive device comprises an implant portion configured for implanting into the patient&#39;s uterine myometrium at a uterine cornu and circumscribing the fallopian tube&#39;s opening and a cap portion removably connected to the implant portion. The cap portion has an impermeable membrane substantially impermeable to the passage of reproductive cells, wherein when the implant portion is implanted into the uterine myometrium near the fallopian tube opening circumscribing the fallopian tube opening, the cap portion occludes the fallopian tube. 
         [0012]    According to another embodiment, a method for reversibly sterilizing a patient by occluding the patient&#39;s fallopian tube to prevent passage of reproductive cells is disclosed. The method comprises providing a contraceptive device in a collapsed configuration inside an inner lumen of a delivery cannula, the contraceptive device comprising an implant portion configured for implanting into the patient&#39;s uterine myometrium in a uterine cornu and circumscribing the fallopian tube&#39;s opening; and a cap portion removably connected to the implant portion, the cap portion having an impermeable membrane substantially impermeable to the passage of reproductive cells, wherein a guide wire extends through the contraceptive device. Next, the guide wire is advanced into a fallopian tube and the delivery cannula&#39;s distal end is advanced to the uterine cornu in proximity of a tubal ostium. The contraceptive device is then advanced out from a distal end of the delivery cannula and the implant portion of the contraceptive device is implanted by axially pushing the contraceptive device against the uterine cornu until the implant portion is substantially implanted into the patient&#39;s myometrium. 
         [0013]    Unlike the current tubal sterilization techniques, sterilization achieved using the device of the present disclosure avoids any significant permanent interference with both structure and function of the uterus and fallopian tubes at the microscopic and molecular levels respectively following its removal. The contraceptive device of the present disclosure can be delivered to the appropriate site transcervically using either a hysteroscope or other existing well established technologies such as a cannula, thus avoiding an abdominal incision and surgical procedure within the peritoneal cavity that is common to all currently employed methods of tubal sterilization except for the Essure transcervical system. The contraceptive device of the present disclosure in contrast to all current tubal sterilization techniques, provides permanent yet easily reversible cornual sterilization. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    A fuller understanding of the nature and objects of the present invention will become apparent upon consideration of the following detailed description, taken in connection with the accompanying drawings, wherein: 
           [0015]      FIG. 1  illustrates the uterine and tubal anatomy in which the contraceptive devices disclosed herein are shown in place; 
           [0016]      FIGS. 2-3  illustrate an embodiment of the contraceptive device of the present disclosure; 
           [0017]      FIGS. 4-5  illustrate another embodiment of the contraceptive device of the present disclosure; 
           [0018]      FIGS. 6-14  illustrate an example of the implantation procedure for the embodiment of the contraceptive device of  FIGS. 2-3 ; 
           [0019]      FIGS. 15-16  illustrate an example of the procedure for reversing the sterilization achieved with the contraceptive device of the present disclosure; and 
           [0020]      FIG. 17  illustrates an example of a detailed view of the metal mesh frame work for the contraceptive device  100  of  FIGS. 2-3 . 
       
    
    
       [0021]    All drawings are illustrated schematically and the structures illustrated therein are not to scale. 
       DETAILED DESCRIPTION 
       [0022]    This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected,” “connecting,” “attached,” “attaching,” “joined,” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressly described otherwise. 
         [0023]      FIG. 1  illustrates the contraceptive devices  100  of the present disclosure implanted in the fallopian tube ostium of a uterus  50 . As will be discussed in detail below, the contraceptive device  100  is transcervically inserted into the uterus  50  and implanted at the uterine opening of the fallopian tube  60  to block the passage of ovum from the fallopian tube  60 . 
         [0024]    Referring to  FIGS. 2-3 , in one embodiment, contraceptive device  100  comprises a removable cap portion  120  and an implant portion  110 . Both the implant portion  110  and the cap portion  120  are formed of self-expandable metal mesh structure. In one preferred embodiment, the metal mesh structure is made from a shape-memory alloy such as super-elastic Nitinol. The use of such material allows the contraceptive device  100  to be delivered transcervically in a collapsed compact state provided in a delivery cannula  10  (see  FIGS. 6-7 ). When the contraceptive device  100  is deployed out of the distal end of the delivery cannula  10  near the tubal ostium of a uterus, the shape-memory alloy mesh structure of the contraceptive device  100  self-expands into an implant configuration. 
         [0025]    The self-expanding property of such mesh structure made from Nitinol is well-known in stent technology so will not be discussed in detail. Basically the shape-memory metal alloy provides the contraceptive device  100  with a thermal memory of a desired configuration. The shape-memory alloy mesh can be fabricated out of an alloy stock that is about 1/150 inches thick. In one embodiment, the metal mesh can be fabricated by laser cutting the mesh structure out of an alloy stock tube into a mesh having a substantially cylindrical shape. Then this substantially cylindrical metal mesh is shaped into the configuration of the contraceptive device  100  where the distal end forming the implant portion  110  is open and the proximal end forming the removable cap portion  120  is formed into a conical shape. Where Nitinol shape memory metal is used, a particular alloy whose martensitic to austenitic phase transition temperature is just below a human body temperature is preferred. The contraceptive device  100  is deformed into a collapsed compact configuration small enough to fit inside the lumen of the delivery cannula  10  at a temperature below the transition temperature. When the contraceptive device  100  is brought to human body temperature the Nitinol metal mesh structure will elastically return to the original shape which is the implanting configuration shown in  FIGS. 2-3 . But, while the contraceptive device  100  is inside the delivery cannula  10 , it is prevented from expanding back to the original implanting configuration. When the contraceptive device  100  is pushed out of the cannula  10  for implanting inside the patient&#39;s uterus, the device springs back to its implanting configuration. The contraceptive device  100  can be fabricated and configured to go from about 1.4 mm in diameter in the collapsed state inside the delivery cannula  10  to a diameter of about 5 mm at its fully deployed implanting configuration. 
         [0026]    In this embodiment, the removable cap portion  120  of the mesh structure of the device can be coated with a suitable expandible polymer membrane  122  such as PTFE (e.g. Teflon), polyurethane or the like. The membrane  122  is impermeable to ova and spermatozoa. When the contraceptive device  100  is implanted in the patient, the implant portion  110  of the contraceptive device will be imbedded in the myometrium and the implant portion  110  is not covered with the impermeable membrane  122  in order to allow tissue ingrowth through the metal mesh structure for permanent fixation of the contraceptive device. 
         [0027]    On the other hand, the removable cap portion  120  of the contraceptive device  100  is substantially or completely covered with the impermeable membrane  122 . The impermeable membrane  122  may be formed by coating or molding the appropriate polymer in resin form on to the removable cap portion  120  of the metal mesh structure so that the impermeable membrane  122  and the metal mesh structure form a unitary structure. Alternatively, the impermeable membrane  122  can be preformed into the frustoconical shape and then bonded to the metal mesh structure. The attachment may be achieved by an appropriate adhesive or by ultrasonic bonding. 
         [0028]    When the contraceptive device  100  is implanted, although the implant portion is completely embedded in the myometrium of the uterus the removable cap portion  120  is mostly exposed. The removable cap portion  120  being covered with the impermeable membrane  122  provides an impermeable barrier between the tubal ostium (proximal endometrial canal opening) and the endometrial cavity and thus between ovum and spermatozoa. Because the contraceptive device  100  needs to be collapsed into a compact configuration small enough to be fitted inside the delivery cannula  10 , the impermeable membrane  122  is preferably flexible and able to collapse into the compact configuration along with the metal mesh structure of the contraceptive device. 
         [0029]    Continuing with  FIGS. 2-3 , the proximal end of the removable cap portion  120  converges in a substantially frustoconical shape when the contraceptive device  100  is in an expanded configuration (i.e. implanting configuration) with the tip of the conical cap portion  120  being provided with a tip  124 . The tip  124  is configured and adapted to securely hold the impermeable membrane and the expandable metal mesh  121  of the cap portion  120 . This may be achieved by the use of a locking ring  126  provided on the interior side of the cap portion  120 . The locking ring  126  may be configured to couple with the tip  124  by a snap-fitting arrangement while capturing the proximal end of the impermeable membrane  122 . The proximal end of the shape-memory metal mesh  121  can be affixed to the locking ring  126  by any suitable method. Alternatively, the impermeable membrane  122  and the expandable metal mesh  121  can be attached to the tip  124  by an adhesive. If the tip  124  is fabricated from a suitable polymeric material, the impermeable membrane and the expandable metal mesh  121  can be attached to the tip  124  by ultrasonic bonding. Regardless of what attachment method is used to attach the impermeable membrane  122  and the expandable metal mesh  121  to the tip  124 , the attachment must produce an impermeable seal that is impermeable to ovum and spermatozoa. 
         [0030]    Both the tip  124  and the locking ring  126  are cannulated to have a passageway  125  extending therethrough for receiving a guide wire  30  (see  FIGS. 2 ,  3 ,  6 - 12 ). Because the purpose of the contraceptive device  100  is to provide an impermeable barrier between the ovum and the spermatozoa, this passage way  125  must be closed once the contraceptive device  100  is implanted. This can be achieved by a sealing member  127  that operates as a one-way valve provided at the locking ring  126  end or the tip  124  end. In the illustrated example, the sealing member  127  is provided and coupled to the locking ring  126 . The sealing member  127  can be a one-way valve that allows the guide wire  30  to pass therethrough but when the guide wire  30  is removed, it seals itself and closes the passage  125 . The one-way valve can be a mechanical bi-valve or other appropriate sealing device. 
         [0031]    In a preferred embodiment, the tip  124  can be further configured with a ridge  128  or similar structure(s) to be easily grasped by a miniature grasper  20  (see  FIGS. 6 ,  11  and  12 ) for the purpose of securely holding the device during the implanting and removal procedure. The ridge  128  of this embodiment can extend substantially around the circumference of the tip  124 . 
         [0032]    The miniature grasper  20  can be configured to have two or more prongs at its distal end for grasping the tip  124  of the contraceptive device  100 . The grasper  20  will hold the contraceptive device  100  while pushing the contraceptive device into the myometrium tissue until the implant portion  110  is fully implanted into the myometrium. The grasper  20  has sufficiently small diameter to fit within the delivery cannula  10 . Thus, in one embodiment, the grasper  20  can be pre-packaged within a delivery cannula  10  device along with the contraceptive device  100  and the guide wire  30 . In one possible configuration, the contraceptive device  100 , the guide wire  30  and the grasper  20  are situated within a delivery cannula  10  with the contraceptive device  100  near the distal end of the delivery cannula  10 . The guide wire  30  can be provided within the delivery cannula  10  just behind the contraceptive device  100 . The guide wire  30  could be advanced through the one-way valve  127  of the contraceptive device  100  before passage of the delivery cannula into the working channel of a hysteroscope. Alternatively, the guide wire  30  can be advanced after the distal end (the end with the contraceptive device  100 ) of the delivery cannula  10  has been advanced to the proximity of the tubal ostium. If necessary, a delivery sheath may be provided at the entrance to the working channel of the hysteroscope to accommodate the delivery cannula  10 . In this configuration, the grasper  20  is configured and adapted to lie within the lumen of the delivery cannula  10  through the length of the delivery cannula  10  along with the guide wire  30  such that both the grasper  20  and the guide wire  30  can be independently advanced towards the distal end of the delivery cannula  10  or retracted back. To that end, the grasper  20  can have a cannulated structure with a lumen for receiving the guide wire  30  therethrough. Alternatively, the grasper  20  can be configured with a channel running the length of the grasper  20  so that the grasper  20  and the guide wire  30  can be placed within the lumen of the delivery cannula  10  side-by-side. 
         [0033]    In another embodiment, the grasper  20  can comprise two or three prongs fused together and packaged to lie within the length of the delivery cannula  10  alongside the guide wire. The non-fused distal ends would grasp the tip  124  of the contraceptive device  100  and push it along the guide wire into the myometrium. This pronged grasper  20  would then be removed along with the guide wire  30 . The guide wire  30  itself would be packaged within the delivery cannula  10  alongside the fused prongs with its tip lying just proximal to the one way valve  127  of the contraceptive device  100  ready to be advanced through it at the time of implantation. 
         [0034]    Preferably, all components of the contraceptive device  100  are comprised of materials that are relatively biologically inert, durable and resistant to uterine fluids. 
         [0035]    The distal end of the implant portion  110  is configured to be fixed in place in the myometrium close to, but not involving, the uterotubal junction. To enable the initial fixation of the contraceptive device  100  in the myometrium, the distal end of the implant portion  110  can be provided with barbs or barb-like structures  114 . The barbs  114  can be fabricated as integral parts of the shape-memory metal mesh framework. In other words, the barbs  114  are designed into the metal mesh pattern and laser cut out of the same stock material. The barbs  114  are oriented in a longitudinal or axial direction, parallel to the longitudinal axis of the contraceptive device  100  so that the barbs can be driven straight into the myometrium without requiring any twisting motion or generating twisting motion. The distal ends of the barbs  114  have V-shaped tips angled at about 45° to firmly fix the device in place initially (see  FIG. 17 ). The fixation of the contraceptive device  100  is further enhanced by fibrovascular ingrowth of the myometrium tissue through the metal mesh framework of the implant portion  110  that is not covered by the impermeable membrane  122 . 
         [0036]    Between the implant portion  110  and the cap portion  120  of the metal mesh comprising the contraceptive device  100  is a break-away zone  130 . The break-away zone  130  is configured to break or sever when the removable cap portion  120  is deformed by laterally squeezing the cap portion  120 . This feature allows the removable cap portion  120  to be removed after the implant procedure to allow reversal of the sterilization. 
         [0037]    In one embodiment, the break-away zone  130  can be formed by the metal mesh structure having weakened joints along the metal mesh circumscribing the substantially tubular structure of the contraceptive device  100 . Thus, similar to soda can tops being popped open, when the removable cap portion  120  is squeezed laterally, the deformation of the metal mesh structure stresses the weakened joints along the break-away zone  130  and snaps them off. The weakened joints of the metal mesh can be made by crimping or scribing the metal mesh wires after the mesh frame work is fabricated. Alternatively, the implant portion  110  and the removable cap portion  120  of the contraceptive device  100  can be fabricated as two separate pieces and then spot welded together in which the welded joints are of such strength to form the break-away zone  130 .  FIG. 17  shows a detailed view of an example of the metal mesh work for the implant portion  110 , the removable cap portion  120  and the break-away zone  130 . The break-away zone  130  in this example is configured to snap off when the cap portion  120  is deformed by squeezing. 
         [0038]    In another embodiment, the implant portion  110  and the removable cap portion  120  are fabricated as two separate structures and then mechanically fitted together like pieces of a jig-saw puzzle. The mechanical fitting is configured to be sufficiently strong to keep the two portions together until they are separated by laterally squeezing the cap portion  120  in order to remove the cap portion  120 . 
         [0039]    Referring to  FIGS. 6-13 , the procedure of implanting the contraceptive device  100  according to an embodiment will be described. The contraceptive device  100  may be delivered to the implantation site and embedded therein by a number of presently existing and future technologies. In this example, the contraceptive device  100  is provided in its compact collapsed configuration inside a deliver cannula  10  with a guide wire  30  inserted through the contraceptive device  100 . The cannula  10  is used to reach the implantation site transcervically. This can be done either by inserting the cannula  10  through a working channel of a hysteroscope (not shown) or inserting the cannula  10  directly through the cervical canal of the patient. Once the distal end of the cannula  10  is maneuvered to the implantation site, the guide wire  30  is inserted into the fallopian tube ostium  62  (see  FIG. 6 ). The guide wire  30  may be lubricated or coated with a hydrophilic coating material to minimize any cell damage. 
         [0040]    The contraceptive device  100  is then pushed towards to the distal end of the cannula  10  using the grasper  20  and out of the cannula  10  (see  FIG. 7 ) Once fully deployed out of the cannula  10 , the contraceptive device  100  self-expands into the implant configuration (see  FIG. 8 ). The contraceptive device  100  is pushed along the guide wire  30  by the cannula  10  to the correct implantation site several millimeters from the tubal ostium  62  (see  FIG. 9 ). The proper placement of the contraceptive device  100  can be guided by fluoroscopic or ultrasonic image guidance or via the working channel of a hysteroscope with a video capability to that site. To assist in guidance of the delivery cannula  10  using fluoroscopy, an appropriate marker  15  can be provided at the distal end of the delivery cannula  10  that will be readily visible in fluoroscopy. 
         [0041]    Once in the proper location for implantation, the contraceptive device  100  is pushed into the uterine cornu. As shown in  FIG. 9 , the barbs  114  provided at the distal end of the implant portion  110  pierce the endometrium and advance into the myometrium. The implant portion of the contraceptive device  100  circumscribes the fallopian tube opening as the contraceptive device  100  is pushed into the myometrium to the required depth, i.e. until the implant portion  110  is completely implanted into the myometrium (see  FIG. 10 ). The depth of the implantation can be monitored and controlled by using a visual marker provided on the contraceptive device that can be seen on the fluoroscopic image, ultrasonic image or through the working channel of a hysteroscope. Alternatively, a physical stop can be provided on the contraceptive device  100  that can provide a tactile feedback via the cannula  10  to the person performing the operation. Because the metal mesh framework of the contraceptive device  100  circumscribes the fallopian tube opening, the implant does not touch the lining of the fallopian tube which might permanently damage the tube lining. 
         [0042]    As shown in  FIG. 11 , once the contraceptive device  100  is implanted, the cannula  10  can be pulled back exposing the grasper  20  that is engaging the tip  124  of the cap portion  120  of the contraceptive device  100 . The prongs of the grasper  20  are configured to open and release the contraceptive device  100  when the cannula  10  is pulled back sufficiently (see  FIG. 12 ). The guide wire  30  is pulled out of the fallopian tube  60  and the cannula  10  is removed from the patient.  FIG. 13  shows the contraceptive device  100  in its implanted state. The implant portion  110  is fully embedded into the myometrium  55  and the impermeable membrane  122  of the cap portion blocks the opening into the fallopian tube  60 . 
         [0043]    Referring to  FIGS. 14-16 , the procedure for removing the cap portion  120  of the contraceptive device  100  in order to reverse the sterilization will now be described. To remove the cap portion  120 , the cannula  10  with a removing clamp  25  is transcervically inserted into the uterus and guided to the contraceptive device  100 . The removing clamp  25  opens sufficiently wide to fit over the removable cap portion  120  as shown in  FIG. 14 . The cannula  10  is pushed distally toward the implanted contraceptive device  100  thus closing the removing clamp  25  around the removable cap portion  120  laterally squeezing and deforming the cap portion  120  when fully engaged as shown in  FIG. 15 . The deforming of the removable cap portion  120  and thus the deformation of the metal mesh framework causes the break-away zone  130  between the removable cap portion  120  and the implant portion  110  to break separating the removable cap portion  120  from the permanently implanted implant portion  110  as shown in  FIG. 16 . The removed cap portion  120  can now be removed transcervically along with the cannula  10 . Because the implant portion  110  is completely imbedded within the myometrium there is no sign of the implant after the cap portion  120  is removed. This prevents any chance of cornual pregnancy after the reversal procedure that may be caused by ovum getting caught on a protruding piece of the implanted metal mesh. 
         [0044]    Alternatively, the reversal of sterilization by removal of the removable cap portion  120  may be accomplished by the use of a suitably designed fine semi flexible grasping hysteroscopic accessory instrument. The semi-flexible grasping hysteroscopic accessory equipment will be similar to the removing clamp  25  except that it will be inserted into the uterus directly through the working channel of a hysteroscope rather than being inserted first through a cannula  10 . The removable cap portion  120  of the contraceptive device  100  can be removed using a small diameter (5 mm or less) office based hysteroscopic system with a narrow gauge working channel to accommodate the fine removal instrument. 
         [0045]    Referring to  FIGS. 4-5 , a contraceptive device  200  according to another embodiment is disclosed. The contraceptive device  200  has a removable cap portion  120  that is same as the contraceptive device  100 . However, the distal end of the implant portion  210  is configured with a mesh pattern that forms a serrated teeth-like structure  212  as shown. This serrated teeth-like structure  212  allows the contraceptive device  200  to be implanted into the myometrium by twisting or screwing the device into the myometrium. The implant portion  210  is also provided with barbs  214  that opens up at about 45° angle in proximal direction to help fixate the contraceptive device  200  after being screwed into the myometrium. The procedure for implanting the contraceptive device  200  is similar to the procedure described above for the contraceptive device  100  with the difference being that after the contraceptive device  200  is guided to the implant site, it is twisted into the myometrium rather than being pushed straight into the myometrium. In this embodiment, the Nitinol metal mesh may have a double helicoidal mesh pattern to provide the metal mesh structure more rigidity when being twisted into the myometrium. Similar to the contraceptive device  100  of  FIGS. 2-3 , the contraceptive device  200  is also provided in collapsed compact configuration in the cannula  10  before deployment. 
         [0046]    In another embodiment, the metal mesh structure of the implant portion  110  can be configured to be compressed in the longitudinal direction when being pushed against the uterine cornu. The compression of the mesh can impart more rigidity to the contraceptive device, which will facilitate driving the barbs  114  into the myometrium for implantation. 
         [0047]    The contraceptive device&#39;s  100 ,  200  dimensions and configuration will take into account the relevant anatomical dimensions of the region of the uterine cornu and utero tubal junction, as well as the proportions, architecture and physical and biological properties of the different tissues. The configuration of the contraceptive device  100 ,  200  could be substantially conical or cylindrical in shape or a combination thereof as in the embodiments  100  and  200  discussed herein. Such a configuration will allow an adequate distance between the lumen of the utero tubal junction and the contraceptive device to ensure subsequent fibrous reaction to the metal mesh structure of the implant portions  110 ,  210  does not adversely affect in any significant way the utero tubal unit. 
         [0048]    According to another aspect of the present disclosure, implantation of the contraceptive device should preferably take place within the first 9 days of the menstrual cycle but after cessation of menstrual flow. The patient should avoid sexual intercourse during the cycle of placement and should utilize a reliable primary form of contraception immediately thereafter. Such contraception should continue until a suitable imaging system has confirmed satisfactory placement and fixation of the device with no evidence of leakage after an acceptable length of time has elapsed from placement. 
         [0049]    Based on the features of the embodiments of the method disclosed herein, further variations will now become apparent to persons skilled in the art. All such variations are considered to be within the scope of the appended claims and the scope of the appended claims are not to be limited to the particular examples of embodiments discussed herein. For example, the impermeable membrane  122  is not limited to the PTFE embodiment but can be made of any material that is impermeable to ovum and spermatozoa and having other suitable physical characteristics discussed herein. The collapsible and self-expandable shape-memory metal mesh structure of the contraceptive device is not limited to any one particular mesh structure or pattern.