Abstract:
Opposing, contoured panels are controllably opened by either a translational or rotational movement of a driving control rod to controllably open or dilate a cervix. An insertion depth limiter, prevents over-insertion of the panels into the uterus thereby preventing accidental perforation of the uterine wall. The device can be straight, curved or articulated to accommodate anatomical differences.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the filing benefit of, and incorporates by reference, U.S. provisional patent application for “Maasal Dilator,” which was filed Aug. 8, 2006, and which is identified by patent application Ser. No. 60/836,337. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    Many gynecological procedures require the cervix to be dilated or opened. In the prior art, cervical dilation is accomplished by inserting progressively larger-diameter probes, one-by-one into the cervix. A very small is inserted first, which causes the cervix to open by a correspondingly small amount. As is known, the cervix opens gradually. 
         [0003]    After a very small probe is inserted, a slightly larger probe is inserted to cause the cervix to dilate further. One-by-one, progressively larger probes are inserted, with each probe causing the cervix to dilate further. By inserting increasingly larger diameter probes, the cervix is eventually dilated to the diameter required to access the interior of the uterus. 
         [0004]    A problem with the prior art methods and prior art cervical dilation devices is the risk of perforating the uterine wall. Prior art cervical dilation probes can easily be inserted too far into the uterus, so far in fact that they can perforate the uterus. Moreover, cervical dilation using prior several-different diameter art probes, one-by-one is time-consuming. Cervical dilation using prior art probes can easily require more than twenty minutes to perform, prolonging the time required to perform an intra-uterine procedure. 
         [0005]    A cervical dilator that reduces or eliminates the uterine wall perforation risk would be an improvement over the prior art. Moreover, a cervical dilator that can controllably open a cervix, i.e., cause it dilate, in less time than what is required using prior art methods would be an improvement. A cervical dilator that is able to open the cervix to a known diameter and which is also expandable while inside the cervix, would also be an improvement over the prior art. 
       SUMMARY OF THE INVENTION 
       [0006]    There is provided a cervical dilator referred to herein as a maasal cervical dilator, comprised of two or more elongated and contoured panels that form an expandable malecot that can be inserted into a cervix only a limited distance so as to prevent uterus wall perforation. Malecot insertion depth into the cervix  101  is limited by annular shoulder of a cylindrical sleeve that the expandable malecot extends past. The cylinder and its larger-than-the-cervix&#39; inside diameter therefore acts a malecot insertion depth limiter. 
         [0007]    In a fully retracted or collapsed state, the expandable malecot has an outside diameter that allows its insertion into the cervix. It its fully-expanded or opened state, the expandable malecot has an outside diameter significantly greater than the closed state of the cervix. The outside diameter of the shoulder is greater than the cervical diameter after dilation, such that the malecot cannot be inserted into the uterus. 
         [0008]    The contoured panels that form the malecot are coupled to an elongated central control rod, which runs through the length of the panels and the insertion depth limiter. The control rod acts as part of a transmission mechanism, which converts linear or rotational movement of the control rod (or rotation of a thumb nut threaded onto the rod) into radial displacement of the contoured panels. In a preferred embodiment, the contoured panels are attached to the control rod by swing arms that are pivotally attached to both the control rod and the panels such that linear displacement of the control rod along its axis, causes the swing arm to fold outwardly, which in turn causes the panels to expand radially away from the control rod. 
         [0009]    The distal end of the expandable malecot is rounded or blunted and smooth to facilitate cervix insertion and to avoid trauma to the cervix. In one embodiment, swing arms that enable expansion of the malecot panel can themselves be rounded to provide the rounded distal end. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of an embodiment of cervical dilator with the malecot panels in their fully retracted position; 
           [0011]      FIG. 2  is a perspective view of the cervical dilator of  FIG. 1 , but with the malecot panels in an extended position; 
           [0012]      FIG. 2A  is a schematic depiction of the swing arm and control geometry that effectuates radial displacement of the contoured panels by the linear displacement of the control rod; 
           [0013]      FIG. 3  is a cross-sectional depiction of the cervix dilator in use; 
           [0014]      FIG. 4 . shows a cross-section of the malecot along sections lines  4 - 4  in  FIG. 1 , with the panels in their fully retracted position; 
           [0015]      FIG. 5  shows a cross-section of the malecot along sections lines  4 - 4  in  FIG. 1 , with the panels in an extended position; 
           [0016]      FIG. 6  is a length-wise cross-section of a cervix dilator, showing additional details of the transmission mechanisms 
           [0017]      FIG. 7  shows a cervix dilator an alternate embodiment of a transmission mechanism, one that converts rotational movement into radial displacement; 
           [0018]      FIGS. 8 and 9  show another embodiment of a cervix dilator wherein one panel is fixed and the second panel translates radially by movement of the control rod; and 
           [0019]      FIGS. 10A ,  10 B,  11 A,  11 B and  12   w  depict alternate embodiments that use wavy or boustrophedonic surfaces to controllably displace panels away from each other. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a perspective view of a Maasal cervical dilator  100  according to one embodiment of the invention claimed herein. The dilator  100  is comprised of a thin and elongated dilating element embodied as dilating malecot  110  and an insertion depth limiter  112 , which has an intermediate portion  111  that is narrowed to provide a grip for a user. The malecot  110  is in turn comprised of first and second elongated and contoured deflection panels  110 A and  110 B, which can be expanded away from each other as described below. 
         [0021]    The malecot  110  has a rounded or tapered distal end  103 , shaped as such to facilitate insertion of the malecot  110  and to avoid trauma to the cervix and cervical of the uterus as shown in  FIG. 3 . The rounded distal end  104  of the malecot is provided by rounding the distal end  104  of each of the contoured deflection panels  110 A and  110 B. In an alternate embodiment, a tapered and smoothened end is provided by modifying the distal set of the swing arms,  122 , to form a tapered and smooth advancing end and articulate with the expanding malecots,  110 . 
         [0022]    The distal end  104  of the malecot  110  is separated from the proximal end  106  by a predetermined distance or length along a longitudinal axis  108  (not shown in  FIG. 1 ) that runs through the center of the dilator  100 . The distance between the proximal end  106  in the distal end  104  corresponds to the length of the malecot  110  that will extend into the cervical canal. The malecot&#39;s length is therefore preferably equal to or slightly less than the length of the cervical canal so that the entire length of the canal can be dilated, although malecots longer than and shorter than the cervix canal&#39;s length are also contemplated by the invention disclosed and claimed hereinafter. The longitudinal axis  108  along which the malecot&#39;s length is measured, can be considered to be a geometric center line that runs through the geometric center of the dilating element  102  as well as the insertion depth limiter  112 , which is described below. In alternate embodiments, however, the longitudinal axis  108  can be off-center from the geometric center line. 
         [0023]    The insertion depth limiter  112  acts as a handle for a user but it also importantly prevents the malecot  110  from being inserted too deeply. The narrowed portion  111  provides structure that improves the user&#39;s grip on the device. A circumferential groove  113  around the exterior surface of the insertion depth limiter  112  near the proximal end  106  of the malecot  110  is sized, shaped and arranged to accept the rim of the mouth of a prophylactic cover, not shown in the drawings. 
         [0024]      FIG. 2  is a perspective view of Maasal dilator  100  but with the contoured deflection panels  110 A and  110 B of the malecot  110  radially displaced from an elongated control rod  114  that itself has a central axis coincident with the longitudinal axis  108  of the dilating element  102  and the insertion depth limiter  112 . The deflection panels  110 A and  110 B are radially displaced away from the control rod  114  and the longitudinal axis  108  by the deflection of the several swing arms  122  that extend between the control rod  114 . 
         [0025]    Each of the swing arms  122  are rigid rods or tubes that have first and second opposing ends  124  and  126  that are each pivotally connected to the deflection panels  110  and control rod  114  respectively. Since the swing arms  122  are rigid, they are virtually incompressible such that a radial force exerted on the end attached to the back side of the deflection panels  110 A and  110 B will cause the swing arms  122  to rotate about the opposite end, i.e., the end attached to the control rod. Thus, if the angle between the swing arms  122  and the control rod  114  is greater than zero, the application of an axial force on the control rod  114  that causes the control rod  114  to move toward the handle  202  will create an axial force down the length of the swing arms  122  but it will also induce a radial force at the swing arm&#39;s point of attachment at the panels  110 A and  110 B. 
         [0026]    The axial force exerted on the swing arms  122  by retraction of the control  114  toward the handle  202  will cause the deflection panels  110 A and  110 B to butt up against the shoulder  118  of the insertion depth limiter  112 . The radial force, however, will urge the panels outwardly, causing them to push against the cervix, in turn causing the cervix to dilate. In one embodiment, three swing arms are used to deflect each panel  110 : one arm at each of the distal and proximal ends and one arm between the proximal and distal ends to prevent the panel  110  from bending and to prevent “waisting” of the panels to insure equal dilation along the whole length of the cervix. 
         [0027]    Radial displacement of the panels  110  relative to the control rod  114  (as well as the central axis  108 ) is accomplished through the control rod  114 . In the embodiment shown in  FIGS. 1 ,  2  and  3 , translational movement of the control rod  114  along the central axis  108  causes the panels  110 A and  110 B to deflect outwardly. 
         [0028]      FIG. 2A  shows how the longitudinal movement of the control rod  114  from right to left, or “toward” the proximal end  106  of the panels  110  (as well as toward the control handle  202 ) will cause the panels  110  to deflect outwardly and radially away from the control rod  114 . Thus radial displacement and radial expansion of the malecot  110  can be effectuated and controlled by a linear displacement (or linear movement) of the control rod relative to the insertion depth limiter  112  and the panels  110 . 
         [0029]    In  FIG. 2A  the vector A depicts movement of the control rod  114  vis-à-vis the swing arms  122 . The two fixed-length line segments S 1  and S 2  represent two swing arms, each of them having a common end P and opposing ends Q 1  and Q 2 . 
         [0030]    As can be seen in  FIG. 2A , the radial distance between the ends Q 1  and Q 2  and the line representing vector A is denoted in  FIG. 2A  as “d.” The distance “d” is equal to the length of the line segments S 1  or S 2 , which is “L”, multiplied by the sine of the angle θ formed between the line segments and the vector A. The equation is written as: 
         [0000]        d =( L )·sin θ  (1) 
         [0031]    Since the total radial displacement distance between two panels  110 A and  110 B is equal to 2d, for every angle θ, there will be a corresponding total radial expansion or displacement equal to 2L sin θ, where d=L sin θ. 
         [0032]    Those of ordinary skill in the art will recognize that since “d” is equal to L multiplied by sin θ, the lateral translation of the control rod  114  for any value of the panel expansion “d,” relative to a fixed point, such as the insertion depth limiter, is equal to L, multiplied by cosine θ. Therefore, for every radial displacement of 2L sin θ, the corresponding linear displacement of the control rod will be L cos θ. Thus, in an alternate embodiment, control rod  114  is marked with displacement indicator lines  115  as shown in  FIGS. 3 ,  6  and  7 , which can be used to directly display radial displacement or opening of the malecot&#39;s panels  110 A and  110 B relative to each other or relative to the control rod  114  central axis. As set forth above, the spacing between the lines  115  on the control rod or other indicator rod will be non-linear, when using a swing-arm transmission described above. 
         [0033]    Referring again to  FIG. 2A , it can be seen that as the vector A moves to the left in  FIG. 2A , the angle θ will increase and “d” will increase. It is also important to note, however, that if the angle θ is zero or less than zero, the axial force exerted on the line segments S 1  and S 2  by the force represented by vector A will be entirely compressive, i.e., no radial force will be exerted at points Q 1  and Q 2 . If no radial force is exerted at Q 1  and Q 2 , neither of them will move away from the vector A. Thus, it is important that the swing arms  122  form a non-zero angle with the longitudinal axis  108  when the panels  110 A and  110 B are in their fully-retracted position in order to insure that a radial force will be exerted on the swing arms  122  and hence on the panels  110 A and  110 B. 
         [0034]      FIG. 4  shows an end view of the dilating element  102 , taken along the section lines  4 - 4  shown in  FIG. 1 . In  FIG. 4 , the deflection panels are  110 A and  110 B fully retracted and the distance “d” is small. 
         [0035]      FIG. 5  shows the same end view of the dilating element  102 , albeit with the deflection panels radially displaced from the control rod  114 . As can be seen in  FIG. 4  and  FIG. 5 , the contoured panels  110 A and  110 B that form the malecot  110  are radially expandable relative to the longitudinal axis  108  and the control rod  114 . Those of ordinary skill in the art will see that  FIGS. 1 ,  2 ,  2 A demonstrate that the radial displacement ( 2   d ′) of the panels  110 A and  110 B, which form the malecot  110  will be a function of the length of the swing arms  122  and the linear movement of the control rod along the longitudinal axis  108 . 
         [0036]    At least one significant advantage of the Maasal cervical dilator  100  over the prior art is that cervical dilation can be precisely controlled. Another significant advantage is that penetration depth of the malecot  110  is limited to be the length of the two elongated and contoured panels  110 A and  110 B by the shoulder  118  of the insertion depth limiter  112 . 
         [0037]    Referring again to  FIG. 1  and  FIG. 2 , the insertion depth limiter  112  is essentially a tube or cylinder having an outside diameter at the end next to the panels  110 A and  110 B that is large enough so that it cannot be inserted into the cervical canal. At the proximal end of the malecot  110 , the insertion depth limiter  112  the shoulder  118  diameter (See the outside diameter “D” in  FIG. 7 .) is large enough to prevent it from being accidentally inserted into the cervical canal. Since the insertion depth limiter  112  is too large in diameter to enter the cervix or the canal, perforation of the uterus by the malecot  110  is prevented. 
         [0038]      FIG. 3  shows a diagrammatic representation of the human cervical canal  101 .  FIG. 3  also shows the malecot  110  and its contoured panels  110 A and  110 B inserted into the canal  101 . The embodiment of the insertion depth limiter  112  shown in  FIG. 3  has an outside diameter that blocks the limiter  112  from entering the canal  101 . The distance or space between the outside diameter and the exterior surfaces of the malecot  110  form a shoulder  118 . The shoulder  118  abuts the opening of the cervical canal. 
         [0039]    In a preferred embodiment the length of the panels  110 A and  110 B is approximately 5 cm. The outside diameter of the insertion depth limiter  112  is at least 2 cm., in order to prevent the insertion depth limiter  112  from entering the cervix. The outside diameter of the collapsed or closed malecot  110  is preferably less than 4 mm and preferably 3-3.5 mm. At the malecot&#39;s  110  maximum displacement, the spacing between the contoured panels  110 A and  110  is preferably about 2 cm. Because of anatomical differences and because some cervix&#39; may be partially dilated for a various reasons, alternate embodiments also include malecots having a collapsed or closed outside diameter of 1 cm. or more. 
         [0040]      FIG. 6  shows a cross-sectional view of the dilating element  102  and a partial cut away of the insertion depth limiter  112 .  FIG. 6  also shows the circumferential groove  113  that accepts a binding ring of an elastic cover (not shown) and the narrowed grip region  111 . More importantly, however,  FIG. 6  shows additional detail of a transmission mechanism  200  that both couples the control rod  114  to the malecot  110  and which controls a linear movement of the control rod  114  so as to cause the malecot  110  to displaced radially. 
         [0041]    In  FIG. 6 , two operator handles  202  and  203  cooperate to effectuate translation of the control rod  114  with respect to the malecot  110 , the panels  110 A and  110 B, and the insertion depth limiter  112 . An axis or pivot point  204  allows one of the handles  202  or  203 , to pivot or rotate around the axis  204  and displace the control rod  114 . Those of ordinary skill in the art will recognize that either one of the handles or both handles can be configured to move the control rod  114  along its axis. When the control rod  114  is moved toward the handles  202  and  203 , the panels  110 A and  110 B will butt up against the shoulder  118  but they will also be urged outwardly and away from the control rod  114 . 
         [0042]      FIGS. 1 ,  2  and  6  depict one implementation of a transmission mechanism  200  that couples the control rod to the malecot  110  such that linear movement of the control rod  114  along the longitudinal axis  108  causes the malecot  110  to displaced radially.  FIG. 7  shows another embodiment of a transmission mechanism. 
         [0043]    In  FIG. 7 , the transmission mechanism  200  includes a knurled thumb nut  208 , the interior of which is threaded to mate with exterior threads on the control rod  114 . As the thumb nut  208  rotates clockwise or counterclockwise in the handle of the maasal cervical dilator  100 , it causes the control rod  114  (having an exterior thread that mates with and engages threads inside of the thumb nut  208 ) to translate linearly. In the embodiment shown, the threaded control rod  114  retracts into a handle  117 . The handle  117  is provided with a window through which the deflection scale markings  115  can be seen. When the control rod  114  moves along the axis  108  by the rotation of the thumb nut  208 , the contoured panels  110 A and  110 B that comprise of the malecot  110  will displaced radially with respect to the axis  108 . 
         [0044]    In the embodiment shown in  FIG. 7 , rotation of the thumb nut  208  will cause radial displacement of the panels  110 A and  110 B and hence the enlargement i.e. displacement of the malecot  110 . The thumb nut  208  can also be attached to the control rod  114  and rotably mounted to the insertion depth limiter  112  such that the control rod  114  rotates with the fixed thumb nut  208 . In such an alternate embodiment, the swing arms are pivotally attached to freely-rotating nuts that are threaded onto the control rod (not shown) in order to allow the control rod to rotate within the nuts to which the swing arms are attached. In such an embodiment, rotation of the thumb nut  208  will cause the swing arms to translate along the axis  108 , however, the control rod  114  will not. 
         [0045]      FIGS. 8 and 9  depict another embodiment of a transmission mechanism  200  that couples the control rod  114  to the malecot  1110  such that linear movement of the control rod  114  will cause the malecot  110  contoured panels to displaced radially. In these figures, one panel  110 C is fixed to the insertion depth limiter  112  but the other panel  110 D is free to move radially and laterally. 
         [0046]    As the control rod  114  is pulled to the left, i.e., toward the handle  203 , the proximal end  106  of the moveable panel  110 D slides outwardly as it slides “up” or away from the fixed panel  110 C, on a ramped slot  119  formed into the shoulder  118  of the insertion depth limiter  112 . As the proximal end  106  slides “up” the ramped slot  119  under the force exerted by the control rod  114 , the panel  110 D also slides away from the distal end toward the handle  203 . 
         [0047]      FIG. 10A  and  FIG. 10B  show yet another embodiment of a maasal cervical dilator. Panels  110 E and  110 F have a smooth side  180  facing outwardly or away from the control rod  114  and a wavy, sinusoidal or boustrophedonic side  181  that faces inwardly and toward the control rod  114 . In the collapsed or compressed state shown in  FIG. 10A , the boustrophedonic sides  181  nest together. The panel  110 E is fixed to the shoulder of the insertion depth limiter  112 ; the other panel  110 F is slidably coupled to an inclined ramp  119  cut into the shoulder  118 . Translational movement of the opposite panel  110 F toward the handle  203  will cause the second panel  110 F to ride “up” the slot ramp  119  but also radially away from the first panel  110 E as shown in  FIG. 110B . Thus, by moving one panel  110 F through the lateral translation of the control rod  114 , the distance between the smooth sides  180  can be controllably increased. 
         [0048]      FIG. 11A  and  FIG. 11B  show a variation of the embodiment shown in  FIGS. 10A and 10B . In  FIGS. 11A and 11B , the panels  110 G and  110 H have a smooth side  180  facing outwardly as in  FIGS. 10A and 10B . They also both have a wavy, sinusoidal or boustrophedonic side  181  that faces inwardly and toward the control rod  114 , as in  FIGS. 10A and 10B . In  FIGS. 11A and 11B , however, both of the panels  110 G and  110 H are translated relative to a fixed central deflection panel  113 , both sides of which are boustrophedonic such that the panels  110 G,  110 H and the deflection panel  113  can all be nested together in a collapsed state shown in  FIG. 11A . In  FIG. 11B , however, both of the panels  110 G and  110 H are pulled into slots formed in the shoulder  118 . As the panels  110 G and  110 H move relative to the central deflection panel  130 , both the panels are urged away from the panel  130  by the crests of the boustrophedonic surfaces. 
         [0049]    In yet another embodiment and as shown in  FIG. 12 , the panels in  FIGS. 11A and 11B  are held in place and the central deflection panel  113  is translated laterally relative to the panels  110 G and  110 H to cause the panels to separate. 
         [0050]    Those of ordinary skill in the art will appreciate that the various structures shown in the figures are controllable dilation devices that perform at least the function of controllably dilating a cervix, and importantly, while the device is inside the cervix. Two contoured panels make up the malecot in the embodiments shown in the figures, however, alternate and equivalent embodiments include three, four or more such panels, provided that additional panels are appropriately driven by the control rod. In the embodiments, shown, lateral or rotational movement of a control rod causes the radial deflection of at least one panel, relative to the control rod and/or a second panel, which can also be fixed or movable. 
         [0051]    The structure shown in the figures and identified by reference numeral  112  is an insertion depth limiting device that performs a function of limiting the insertion of any kind of malecot into a cervical canal, whether the malecot is expandable or not. By limiting insertion depth, trauma to the uterus can be avoided. 
         [0052]    In each of the foregoing embodiments, it is important to note that the distal end  104  of the dilating element  102  is rounded or blunt, to facilitate insertion of the dilating element into the cervical canal. Blunting or rounding the end of the distal end  104  of the dilating element  102  will also reduce the likelihood of cervical canal injury as the dilating element  102  is inserted into the canal. 
         [0053]    In yet another embodiment, the malecot panels  110  and perhaps part of the insertion depth limiter  112  can be wrapped in an elastic prophylactic cover, similar to a condom in order to further minimize trauma. Such a cover can also facilitate removal of the device from the cervix. The groove  113  at the proximal end of the insertion depth limiter  112  can be gripped by an elastic band formed into an elastic prophylactic cover placed over the maasal cervical dilation device but which is not shown for clarity. 
         [0054]    From the foregoing, those of ordinary skill in the art will appreciate that Maasal cervical dilator  100  provides a closely controlled dilation mechanism by which a physician or other caregiver can more carefully and less painfully effectuate cervical dilation without having to use multiple different devices, which the prior art requires. While the device shown above is straight, alternate embodiments of the invention include dilators having malecot panels  110 A and  110 B that are curved or articulated to accommodate anatomical differences. In addition, the insertion depth limiter  112  can also be curved or articulated, itself or relative to the malecot panels to accommodate anatomical differences. 
         [0055]    Those of ordinary skill in the art will also appreciate that the maasal dilator  100  described above and shown in the figures can be assembled from injection molded plastic pieces, the manufacturing cost of which is quite low. By assembling such a device it is feasible to construct a single-use dilator, the sterility of which could be more reliably assured. An alternate embodiment of the cervix dilator  100  described above could also be assembled from stainless steel or other durable materials that could be re-used. 
         [0056]    The foregoing description and the illustrations in the various figures are all examples of preferred embodiments. The true scope of the invention described herein is set forth in the appurtenant claims.