Patent Publication Number: US-2022226021-A1

Title: Methods and apparatus for preventing vaginal lacerations during childbirth

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/050,287, filed Feb. 22, 2016, now U.S. Patent Application Publication No. 2016/0166282, which is a continuation of U.S. application Ser. No. 13/876,920, filed Jun. 14, 2013, now U.S. Patent Application Publication No. 2013/0253376, which is a national phase of International Application No. PCT/US2011/032324, filed Apr. 13, 2011, which application is a continuation-in-part of International Application No. PCT/US2010/052528, filed Oct. 13, 2010. These applications are herein incorporated by reference in their entirety. 
    
    
     INCORPORATION BY REFERENCE 
     All publications, including patents and patent applications, mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. 
     FIELD OF THE INVENTION 
     Devices and methods are described generally relating to preparing tissue for childbirth. More specifically, the devices and methods described herein are intended to prepare and dilate vaginal tissue during labor so as to prevent pelvic floor damage, and vaginal and perineal lacerations. 
     BACKGROUND OF THE INVENTION 
     Approximately 134 million women give birth worldwide each year, of whom 3.0 million give birth vaginally in the United States. Approximately 8 out of 10 women who give birth vaginally will experience some degree of vaginal tearing. In the U.S., roughly 1.2 million, or 40%, experience a spontaneous laceration or episiotomy (planned surgical cut for high risk patients) that requires surgical repair. Between 1.5% and 15% of lacerations are considered severe and require extended healing time and pain management, and can result in difficult reparative surgery and a considerable decrease in quality of life measurements. Additionally, 15-35% of women suffer damage to their pelvic floor muscles, where the muscles are being physically pulled off of the pelvic bone or over-stretched to the point where they become functionally impaired. The direct costs of treating perineal lacerations to the healthcare system is estimated to total over $650 million each year, with treatments aimed at future pelvic floor disorders even higher. 
     Specific risk factors for perineal lacerations during childbirth have been identified, leading to above-average incidence in patient populations. These risk factors include nulliparity (primigravidity, first pregnancy), short perineal body, instrumental delivery (forceps-assisted delivery, vacuum-assisted delivery), prolonged second stage of labor (&gt;1 hour), epidural analgesia, intrapartum infant factors (birth weight over 4 kg, persistent occipitoposterior position, shoulder dystocia), episiotomy, mediolateral or midline, previous anal sphincter tear, maternal age &gt;30, and Asian ethnicity. In addition to the risk factors listed above, perineal lacerations have been linked with a higher incidence of many pelvic floor disorders such as infection, incontinence and prolapse. In general, pregnancy and birth have been linked as a cause of many pelvic floor disorders. However, the exact physiologic mechanisms that lead to many of these disorders are under investigation. It is thought that damage to the pelvic floor musculature during childbirth may be one of the most significant causes of pelvic floor disorders. 
     During vaginal delivery, labor and delivery are clinically divided into three stages. The first stage begins with cervical effacement and is completed with full cervical dilation that will allow the passage of the fetus through the birth canal. The second stage is defined by the passage of the fetus through the birth canal, described as the Cardinal Movements of Labor. It begins with complete cervical effacement and dilation and ends in the delivery of the fetus. The third stage is comprised of the separation and expulsion of the placenta. 
     During the first phase of labor, the birth canal is functionally closed and maintained in proper position by a number of layers of muscular and connective tissues that collectively form the pelvic floor. During the second phase of labor, the presenting part of the fetal head descends into the birth canal and exerts direct pressure on the pelvic floor. The fetus passes through the birth canal by stretching the fibers of the levator ani muscle and connective tissues, drastically distending and damaging the pelvic floor musculature, and stretching the perineum into a thin membranous structure that often lacerates during the process of delivery. 
     Pelvic floor and perineal tissues dilate rapidly during the second phase of labor. The introitus, or opening of the vagina, for the average woman, has a baseline resting diameter of roughly 2.6 cm. During the first phase of labor, while the cervix is dilating, the vagina stays at this baseline diameter and only when the baby has passed through the cervix does this tissue dilate from 2.6 cm up to 10 cm, the average head diameter of a newborn baby. This 3.8× expansion in diameter and approximately 15× expansion in area occurs in a matter of seconds to minutes. 
     Currently, there are no devices or tools that have proven to significantly reduce trauma to the pelvic floor during vaginal delivery, and there are no other devices that can be used to isolate the variables associated with pelvic floor disorders resulting from childbirth. No effective treatments exist to assist a woman in preconditioning the tissues of the vagina and perineum prior to and during labor. 
     Historically, gourds of increasing size have been used in Africa in an attempt to prepare the tissue for labor. Today, there are techniques such as perineal massage, hot compresses and “hands-on” delivery that can be performed in the hospital and have anecdotally showed promise, but none of these have been proven to be effective in the clinical trial setting. 
     One device previously introduced with the goal of pre-stretching tissue to prevent lacerations is called the Epi-No. The Epi-No is a small balloon that was intended to be used at home by the pregnant woman, 1-3 months before the baby was due. The goal was to inflate the balloon up to approximately 5 cm, at which time the woman would then practice pushing out the device. A problem with such a balloon-style dilator is that it can change in shape and size during expansion, which can result in poor stability of the device in the vagina and inability to accurately gauge and control the amount of dilation. 
     Vaginismus is a condition that causes involuntary tightness of the vagina during intercourse, caused by involuntary contractions of the pelvic floor muscles surrounding the vagina. Vaginismus can be painful, thereby preventing enjoyment of intercourse. Vaginal dilators combined with appropriate exercises have helped some women overcome these involuntary muscle contractions. 
     SUMMARY OF THE INVENTION 
     A vaginal dilation device is provided comprising a handle, a plurality of arms coupled to the handle, each arm having a pad disposed thereon that is shaped and configured to conform to a vagina, an expansion mechanism coupled to the arms and configured to move the arms and the pads radially outwards from the device, and a force sensor disposed on the device and configured to measure a force applied against the pads. 
     In some embodiments, each of the plurality of arms comprises a scissor-like assembly coupled to each of the pads. The expansion mechanism can be coupled to a central rod which is coupled to the handle and the arms, wherein axial movement of the central rod changes a distance of the pads from the central rod. 
     In one embodiment, actuation of the expansion mechanism is configured to move the central rod proximally towards the handle to move the arms and pads radially outwards from the central rod. 
     In some embodiments, the pads are arranged in a substantially parallel configuration as the arms and pads move radially outwards. 
     In some embodiments, the vaginal dilation device further comprises a closed configuration wherein the pads are arranged circumferentially around the central rod, and an expanded configuration wherein the pads are extended away from the central rod and away from adjacent pads. In one embodiment, an outer diameter of the pads in the closed configuration is less than 4 cm. In another embodiment, an outer diameter of the pads in the expanded configuration is approximately 8-10 cm. 
     In one embodiment, the vaginal dilation device further comprises a quick-release mechanism configured to quickly reduce an outer diameter of the device. In some embodiments, the device further comprises an actuation mechanism disposed on the handle that is configured to engage the quick-release mechanism. In another embodiment, the device further comprises a bump-release disposed on a distal portion of the device that is configured to engage the quick-release mechanism. In some embodiments, the bump-release is configured to be engaged by a baby entering a vaginal canal. 
     In some embodiments, a center of mass of the vaginal dilation device shifts forward under the pads as the device is expanded from the closed configuration to the expanded configuration. 
     In one embodiment, the vaginal dilation device further comprises a diameter sensor configured to indicate a dilation diameter of the vagina. 
     In some embodiments, the vaginal dilation device further comprises a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards based on the force measured by the force sensor. For example, in some embodiments, the force sensor can measure a force applied by the pads, and the controller can automatically expand or contract the device based on the measured force. The controller can automatically increase the applied force if the measured force is too low, or can automatically decrease the applied force if the measured force is too high (e.g., the applied force is above a force threshold). 
     In some embodiments, the controller is configured to automatically move the arms and the pads radially outwards to apply a constant force to the vagina with the pads. In some embodiments, the vaginal dilation device further comprises a motor coupled to the central rod and a controller coupled to the force sensor and the motor, the controller configured to automatically move the central rod axially, and the arms and the pads radially outwards, based on the force measured by the force sensor. In some embodiments, the device further comprises a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards until the force measured by the force sensor exceeds a force threshold. 
     In other embodiments, the controller is configured to automatically move the central rod axially to apply a constant force with the pads. 
     In some embodiments, the expansion mechanism is configured to automatically move the arms and the pads of the device radially outwards at a constant force. In some embodiments, the expansion mechanism comprises a spring coupled to the central rod, wherein the spring pushes against the central rod with a constant force to move the arms and the pads radially outwards from the central rod. In one embodiment, the constant force of the spring is user adjustable. 
     In some embodiments, a force applied by the spring to the dilation device can be adjusted. In other embodiments, the spring can be an adjustable clock spring. In some embodiments, a pivot point of the spring can be adjusted. 
     Some embodiments of the vaginal dilation device further comprise an expandable sheath disposed over the pads. Other embodiments further comprise a working channel disposed on or in the device. 
     In some embodiments of the vaginal dilation device, the force sensor comprises a plurality of force sensors disposed on the pads. In other embodiments, the force sensor comprises a plurality of force sensors disposed under the pads. In other embodiments, the force sensor comprises a plurality of force sensors disposed on the plurality of arms. 
     Some embodiments of the vaginal dilation device further comprise a clutching mechanism configured to prevent over-expansion of the pads. Other embodiments further comprise an automatic oscillation mechanism configured to prevent pressure necrosis. 
     In one embodiment of the vaginal dilation device, none of the pads contact a urethra or any nerve bundles positioned along an anterior portion of the vagina of the patient when the pads move radially outwards from the device. In other embodiments, none of the pads contact a perineum of the patient when the pads move radially outwards from the device. 
     In some embodiments, the expansion mechanism is remotely coupled to the arms via a flexible assembly. 
     In some embodiments, the vaginal dilation device further comprises a cam coupled to the expansion mechanism to linearize a force needed to expand the device from a closed configuration to an expanded configuration. In one embodiment, the cam is a ratcheted cam. In another embodiment, the cam is a geared cam mechanism with multiple gears. In some embodiments, a lever or bump mechanism can be utilized to linearize the force needed to expand the device from the closed configuration to the expanded configuration. 
     In some embodiments, the expansion mechanism can comprise a stent or yurt-like device. In other embodiments, the expansion mechanism can comprise a living hinge structure. 
     Another vaginal dilation device is provided, comprising, a handle, a plurality of arms coupled to the handle, each arm having a pad disposed thereon that is shaped and configured to conform to a vagina, and an expansion mechanism coupled to the arms and configured to move the arms and the pads radially outwards from the device at a constant force. 
     In some embodiments, each of the plurality of arms comprises a scissor-like assembly coupled to each of the pads. The expansion mechanism can be coupled to a central rod which is coupled to the handle and the arms, wherein axial movement of the central rod changes a distance of the pads from the central rod. 
     In one embodiment, actuation of the expansion mechanism is configured to move the central rod proximally towards the handle to move the arms and pads radially outwards from the central rod. 
     In some embodiments, the pads are arranged in a substantially parallel configuration as the arms and pads move radially outwards. 
     In some embodiments, the vaginal dilation device further comprises a closed configuration wherein the pads are arranged circumferentially around the central rod, and an expanded configuration wherein the pads are extended away from the central rod and away from adjacent pads. In one embodiment, an outer diameter of the pads in the closed configuration is less than 4 cm. In another embodiment, an outer diameter of the pads in the expanded configuration is approximately 8-10 cm. 
     In one embodiment, the vaginal dilation device further comprises a quick-release mechanism configured to quickly reduce an outer diameter of the device. In some embodiments, the device further comprises an actuation mechanism disposed on the handle that is configured to engage the quick-release mechanism. In another embodiment, the device further comprises a bump-release disposed on a distal portion of the device that is configured to engage the quick-release mechanism. In some embodiments, the bump-release is configured to be engaged by a baby entering a vaginal canal. 
     In some embodiments, a center of mass of the vaginal dilation device shifts forward under the pads as the device is expanded from the closed configuration to the expanded configuration. 
     In one embodiment, the vaginal dilation device further comprises a diameter sensor configured to indicate a dilation diameter of the vagina. 
     In some embodiments, the vaginal dilation device further comprises a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards based on the force measured by the force sensor. For example, in some embodiments, the force sensor can measure a force applied by the pads, and the controller can automatically expand or contract the device based on the measured force. The controller can automatically increase the applied force if the measured force is too low, or can automatically decrease the applied force if the measured force is too high (e.g., the applied force is above or below a desired constant force threshold). 
     In some embodiments, the controller is configured to automatically move the arms and the pads radially outwards to apply a constant force to the vagina with the pads. In some embodiments, the vaginal dilation device further comprises a motor coupled to the central rod and a controller coupled to the force sensor and the motor, the controller configured to automatically move the central rod axially, and the arms and the pads radially outwards, based on the force measured by the force sensor. In some embodiments, the device further comprises a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards to maintain the force applied by the device at the constant force. In other embodiments, the controller is configured to automatically move the central rod axially to apply a constant force with the pads. 
     In some embodiments, the expansion mechanism is configured to automatically move the arms and the pads of the device radially outwards at a constant force. In some embodiments, the expansion mechanism comprises a spring coupled to the central rod, wherein the spring pushes against the central rod with a constant force to move the arms and the pads radially outwards from the central rod. In one embodiment, the constant force of the spring is user adjustable. 
     Some embodiments of the vaginal dilation device further comprise an expandable sheath disposed over the pads. Other embodiments further comprise a working channel disposed on or in the device. 
     In some embodiments of the vaginal dilation device, the force sensor comprises a plurality of force sensors disposed on the pads. In other embodiments, the force sensor comprises a plurality of force sensors disposed under the pads. In other embodiments, the force sensor comprises a plurality of force sensors disposed on the plurality of arms. 
     Some embodiments of the vaginal dilation device further comprise a clutching mechanism configured to prevent over-expansion of the pads. Other embodiments further comprise an automatic oscillation mechanism configured to prevent pressure necrosis. 
     In one embodiment of the vaginal dilation device, none of the pads contact a urethra or any nerve bundles positioned along an anterior portion of the vagina of the patient when the pads move radially outwards from the device. In other embodiments, none of the pads contact a perineum of the patient when the pads move radially outwards from the device. 
     In some embodiments, the expansion mechanism is remotely coupled to the arms via a flexible assembly. 
     In some embodiments, the expansion mechanism is configured to move the arms and the pads radially outwards from the device at the constant force for a preset period of time. In some embodiments, the preset period of time comprises 5-10 minutes. In other embodiments, the preset period of time comprises 5-60 minutes. In additional embodiments, the preset period of time comprises less than 2 hours. 
     In another embodiment, a vaginal dilation device is provided, comprising a handle, a plurality of arms coupled to the handle, each arm having a pad disposed thereon that is shaped and configured to conform to a vagina, an expansion mechanism coupled to the arms and configured to move the arms and the pads radially outwards from the device, and a diameter sensor disposed on the device and configured to measure a diameter of the device. 
     In some embodiments, each of the plurality of arms comprises a scissor-like assembly coupled to each of the pads. The expansion mechanism can be coupled to a central rod which is coupled to the handle and the arms, wherein axial movement of the central rod changes a distance of the pads from the central rod. 
     In one embodiment, actuation of the expansion mechanism is configured to move the central rod proximally towards the handle to move the arms and pads radially outwards from the central rod. 
     In some embodiments, the pads are arranged in a substantially parallel configuration as the arms and pads move radially outwards. 
     In some embodiments, the vaginal dilation device further comprises a closed configuration wherein the pads are arranged circumferentially around the central rod, and an expanded configuration wherein the pads are extended away from the central rod and away from adjacent pads. In one embodiment, an outer diameter of the pads in the closed configuration is less than 4 cm. In another embodiment, an outer diameter of the pads in the expanded configuration is approximately 8-10 cm. 
     In one embodiment, the vaginal dilation device further comprises a quick-release mechanism configured to quickly reduce an outer diameter of the device. In some embodiments, the device further comprises an actuation mechanism disposed on the handle that is configured to engage the quick-release mechanism. In another embodiment, the device further comprises a bump-release disposed on a distal portion of the device that is configured to engage the quick-release mechanism. In some embodiments, the bump-release is configured to be engaged by a baby entering a vaginal canal. 
     In some embodiments, a center of mass of the vaginal dilation device shifts forward under the pads as the device is expanded from the closed configuration to the expanded configuration. 
     In some embodiments, the vaginal dilation device further comprises a controller coupled to the expansion mechanism and the diameter sensor, the controller configured to automatically move the arms and the pads radially outwards based on the diameter measured by the diameter sensor. For example, in some embodiments, the diameter sensor can measure a diameter of the device, and the controller can automatically expand or contract the device based on the measured diameter. The controller can automatically increase the diameter if the measured diameter is too low, or can automatically decrease the diameter if the measured diameter is too high. 
     In some embodiments, the vaginal dilation device further comprises a motor coupled to the central rod and a controller coupled to the diameter sensor and the motor, the controller configured to automatically move the central rod axially, and the arms and the pads radially outwards at a constant rate of dilation. In some embodiments, the device further comprises a controller coupled to the expansion mechanism and the diameter sensor, the controller configured to automatically move the arms and the pads radially outwards based on the diameter measured by the diameter sensor. 
     Some embodiments of the vaginal dilation device further comprise an expandable sheath disposed over the pads. Other embodiments further comprise a working channel disposed on or in the device. 
     Some embodiments of the vaginal dilation device further comprise a clutching mechanism configured to prevent over-expansion of the pads. Other embodiments further comprise an automatic oscillation mechanism configured to prevent pressure necrosis. 
     In one embodiment of the vaginal dilation device, none of the pads contact a urethra or any nerve bundles positioned along an anterior portion of the vagina of the patient when the pads move radially outwards from the device. In other embodiments, none of the pads contact a perineum of the patient when the pads move radially outwards from the device. 
     In some embodiments, the expansion mechanism is remotely coupled to the arms via a flexible assembly. 
     In some embodiments, the constant rate of dilation is user adjustable. 
     In some embodiments, the vaginal dilation device further comprises a timer configured to alert a user to increase the diameter of the device. 
     In one embodiment, the expansion mechanism comprises a trigger assembly configured to expand the device by a preset dilation increment with a single actuation of the trigger assembly. In some embodiments, the preset dilation increment is user adjustable. 
     A method of dilating a vagina during labor is provided, comprising inserting a vaginal dilation device into the vagina, measuring a force applied by the vaginal dilation device to the vagina, and dilating the vagina with the vaginal dilation device. 
     In some embodiments, the method further comprises pausing dilation of the vagina with the vaginal dilation device when the force applied by the vaginal dilation device to the vagina increases to a first force threshold. In one embodiment, the method further comprises resuming dilation of the vagina when the force applied by the vaginal dilation device to the vagina decreases to a second force threshold. In another embodiment, the resuming dilation step further comprises resuming dilation of the vagina with the vaginal dilation device until the force applied by the vaginal dilation device increases to the first force threshold. In one embodiment, the resuming dilation step further comprises resuming dilation of the vagina with the vaginal dilation device until the force applied by the vaginal dilation device increases to a third force threshold, the third force threshold being larger than the first force threshold. In one embodiment, the first force threshold is larger than the second force threshold. In another embodiment, the first force threshold is less than 8 lbs. of force. 
     In some embodiments of the method, the inserting step further comprises inserting the vaginal dilation device into the vagina during a first phase of labor. The method can further comprise removing the vaginal dilation device from the vagina prior to a second phase of labor. 
     In some embodiments, the measuring a force step further comprises measuring the force with the vaginal dilation device. 
     In one embodiment, the method further comprises measuring a diameter of the vagina with the vaginal dilation device. The method can further comprise dilating the vagina with the vaginal dilation device based on the measured diameter. 
     In some embodiments, the dilating step further comprises dilating the vagina at a constant force with the vaginal dilation device. In other embodiments, the dilating step further comprises manually dilating the vagina with the vaginal dilation device. In an additional embodiment, the dilating step further comprises automatically dilating the vagina with the vaginal dilation device. 
     In another embodiment, the dilating step further comprises dilating the vagina with the vaginal dilation device at a location remote from the patient. 
     Another method of dilating a vagina during labor is provided, comprising inserting a vaginal dilation device into the vagina, and applying a constant force to the vagina with the vaginal dilation device to dilate the vagina. In some embodiments, the constant force is less than 8 lbs. of force. In other embodiments, the constant force is adjustable. 
     In some embodiments of the method, the inserting step further comprises inserting the vaginal dilation device into the vagina during a first phase of labor. In other embodiments, the method comprises removing the vaginal dilation device from the vagina prior to a second phase of labor. In additional embodiments, the method comprises removing the vaginal dilation device from the vagina when the vagina is dilated to a diameter of approximately 8-10 cm. 
     In some embodiments, the method comprises measuring a diameter of the vagina with the vaginal dilation device. 
     In another embodiment, the applying step further comprises automatically applying a constant force to the vagina with the vaginal dilation device to dilate the vagina. In one embodiment, the applying step further comprises automatically applying the constant force to the vagina with a constant force spring disposed in the vaginal dilation device. In another embodiment, the applying step further comprises automatically applying the constant force to the vagina with an automated controller and a motor coupled to the vaginal dilation device. In another embodiment, the applying step further comprises applying the constant force to the vagina with the vaginal dilation device for a preset period of time to dilate the vagina. In some embodiments, the preset period of time comprises less than 5 minutes. In other embodiments, the preset period of time comprises 5-10 minutes. In additional embodiments, the preset period of time comprises 5-60 minutes. In yet another embodiment, the preset period of time comprises less than 2 hours. 
     Another embodiment of the method comprises measuring a force applied by the vaginal dilation device to the vagina. 
     A method of preventing tissue damage during childbirth is provided, comprising inserting a vaginal dilation device into a patient&#39;s vagina during a first phase of labor, and dilating the patient&#39;s vagina with the vaginal dilation device. 
     In some embodiments, the method further comprises removing the vaginal dilation device from the patient&#39;s vagina prior to a second phase of labor. 
     In another embodiment, the dilating step comprises dilating the patient&#39;s vagina to approximately 7-10 cm with the vaginal dilation device. 
     A vaginal exercise device is provided, comprising a handle, a plurality of arms coupled to the handle, each arm having a pad disposed thereon that is shaped and configured to conform to a vagina, an expansion mechanism coupled to the arms and configured to move the arms and the pads radially outwards from the device at a user-specified force, and a force sensor disposed on the device and configured to measure a force applied by the vagina against the pads. 
     In some embodiments, axial movement of the expansion mechanism engages a sloping interior cam surface of the pads to expand the pads radially outward. In other embodiments, the expansion mechanism comprises a cone shaped object. 
     In some embodiments, the expansion mechanism comprises a plurality of living hinges. 
     In one embodiment, the expansion mechanism is coupled to a central rod which is coupled to the handle and the arms, wherein axial movement of the central rod changes a distance of the pads from the central rod. 
     In some embodiments, actuation of the expansion mechanism is configured to move the central rod proximally towards the handle to move the arms and pads radially outwards from the central rod. 
     In some embodiments, the pads are arranged in a substantially parallel configuration as the arms and pads move radially outwards. 
     One embodiment further comprises a closed configuration wherein the pads are arranged circumferentially around the central rod, and an expanded configuration wherein the pads are extended away from the central rod and away from adjacent pads. In one embodiment, an outer diameter of the pads in the closed configuration is less than 1 cm. In another embodiment, an outer diameter of the pads in the expanded configuration is approximately 2-4 cm. 
     Some embodiments further comprise a diameter sensor configured to indicate a dilation diameter of the vagina. 
     In one embodiment, the expansion mechanism is configured to automatically move the arms and the pads of the device radially outwards at the user-specified force. In another embodiment, the expansion mechanism comprises a spring coupled to the central rod, wherein the spring pushes against the central rod with a constant force to move the arms and the pads radially outwards from the central rod. 
     In some embodiments, none of the pads contact a urethra or any nerve bundles positioned along an anterior portion of the vagina of the patient when the pads move radially outwards from the device. 
     In another embodiment, none of the pads contact a perineum of the patient when the pads move radially outwards from the device. 
     In one embodiment, the expansion mechanism is remotely coupled to the arms via a flexible assembly. 
     A cervical dilation device is provided, comprising a handle, a plurality of arms coupled to the handle, each arm having a pad disposed thereon that is shaped and configured to conform to a cervix of a patient, an expansion mechanism coupled to the arms and configured to move the arms and the pads radially outwards from the device at a constant force, a force sensor disposed on the device and configured to measure a force applied against the pads, and an extension mechanism coupling the handle to the arms and the expansion mechanism, the extension mechanism sized and configured to allow the arms to access the cervix while the handle remains outside of the patient. 
     In some embodiments, the expansion mechanism is coupled to a central rod which is coupled to the handle and the arms, wherein axial movement of the central rod changes a distance of the pads from the central rod. 
     In one embodiment, actuation of the expansion mechanism is configured to move the central rod proximally towards the handle to move the arms and pads radially outwards from the central rod. 
     In some embodiment, the pads are arranged in a substantially parallel configuration as the arms and pads move radially outwards. 
     Another embodiment of the device comprises a closed configuration wherein the pads are arranged circumferentially around the central rod, and an expanded configuration wherein the pads are extended away from the central rod and away from adjacent pads. In some embodiments, an outer diameter of the pads in the closed configuration is less than 1 cm. In other embodiments, an outer diameter of the pads in the expanded configuration is approximately 2-10 cm. 
     Some embodiments of the device further include a diameter sensor configured to indicate a dilation diameter of the cervix. 
     In some embodiments, the expansion mechanism is configured to automatically move the arms and the pads of the device radially outwards at the constant force. 
     In other embodiments, the expansion mechanism comprises a spring coupled to the central rod, wherein the spring pushes against the central rod with the constant force to move the arms and the pads radially outwards from the central rod. 
     In some embodiments, each of the plurality of arms comprises a scissor-like assembly coupled to each of the pads. 
     Some embodiments further comprise a quick-release mechanism configured to quickly reduce an outer diameter of the device. 
     In one embodiment, the device further comprises an actuation mechanism disposed on the handle that is configured to engage the quick-release. 
     Some embodiments further comprise a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards based on the force measured by the force sensor. 
     In one embodiment, the controller is configured to automatically move the arms and the pads radially outwards to apply the constant force with the pads. 
     Some embodiments further comprise a motor coupled to the central rod and a controller coupled to the force sensor and the motor, the controller configured to automatically move the central rod axially, and the arms and the pads radially outwards, based on the force measured by the force sensor. 
     In some embodiments, the controller is configured to automatically move the central rod axially to apply the constant force with the pads. 
     Some embodiments further comprise a controller coupled to the expansion mechanism and the force sensor, the controller configured to automatically move the arms and the pads radially outwards until the force measured by the force sensor exceeds a force threshold. 
     A method of dilating a cervix during labor is provided, comprising inserting a cervical dilation device into the cervix, measuring a force applied by the cervical dilation device to the cervix, dilating the cervix with the cervical dilation device, and pausing dilation of the cervix with the cervical dilation device when the force applied by the cervical dilation device to the cervix increases to a first force threshold. 
     In some embodiments the method comprises resuming dilation of the cervix when the force applied by the cervical dilation device to the cervix decreases to a second force threshold. In one embodiment, the resuming dilation step further comprises resuming dilation of the cervix with the cervical dilation device until the force applied by the cervical dilation device increases to the first force threshold. In another embodiment, the resuming dilation step further comprises resuming dilation of the cervix with the cervical dilation device until the force applied by the cervical dilation device increases to a third force threshold, the third force threshold being larger than the first force threshold. 
     In some embodiments, the first force threshold is larger than the second force threshold. In other embodiments, the first force threshold is less than 8 lbs. of force. 
     In some embodiments, the inserting step further comprises inserting the cervical dilation device into the cervix during a first phase of labor. 
     Some embodiments further comprise removing the cervical dilation device from the cervix prior to a second phase of labor. 
     In one embodiment, the measuring a force step further comprises measuring the force with the cervical dilation device. 
     Other embodiments of the method further comprise measuring a diameter of the cervix with the vaginal dilation device. 
     Other embodiments of the method further comprise dilating the cervix with the cervical dilation device based on the measured diameter. 
     In some embodiments, the dilating step further comprises dilating the cervix at a constant force with the cervical dilation device. In additional embodiments, the dilating step further comprises manually dilating the cervix with the cervical dilation device. In another embodiment, the dilating step further comprises automatically dilating the cervix with the cervical dilation device. In another embodiment, the dilating step further comprises dilating the cervix with the cervical dilation device at a location remote from the patient. 
     A method of exercising pelvic muscles surrounding a vagina is provided, comprising inserting a vaginal exercise device into the vagina, applying a constant force to the vagina with the vaginal exercise device, and measuring the force applied by the vagina to the vaginal exercise device. 
     In some embodiments, the constant force is less than 8 lbs. of force. In other embodiments, the constant force is user adjustable. 
     In some embodiments, the vaginal exercise device expands outwardly to a diameter of 2-4 cm. 
     In one embodiment, the applying step further comprises automatically applying a constant force to the vagina with the vaginal exercise device. 
     In another embodiment, the applying step further comprises automatically applying the constant force to the vagina with a constant force spring disposed in the vaginal exercise device. 
     In one embodiment, the applying step further comprises automatically applying the constant force to the vagina with an automated controller and a motor coupled to the vaginal exercise device. 
     In some embodiments, the applying step further comprises applying the constant force to the vagina with the vaginal exercise device for a preset period of time to exercise the pelvic muscles surrounding the vagina. 
     In some embodiments, the preset period of time comprises less than 5 minutes, 5-10 minutes, 5-60 minutes, or less than 2 hours. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1D  illustrate some embodiments of a vaginal dilation device. 
         FIG. 2  is one view of a vaginal dilation device in an expanded configuration. 
         FIGS. 3A-3D  show cross-sectional views of a vaginal dilation device. 
         FIGS. 4A-4B  show cross-sectional views of an automated vaginal dilation device. 
         FIGS. 5A-5D  illustrate various embodiments of pad shapes for use with a vaginal dilation device. 
         FIGS. 6A-6G  illustrate various embodiments of force sensors disposed on or in a vaginal dilation device. 
         FIGS. 7A-7B  show embodiments of a vaginal dilation device with a protective sheath. 
         FIGS. 8A-8D  illustrate various embodiments of a vaginal dilation device having working channels or through ports. 
         FIG. 9  illustrates a vaginal dilation device with a quick-release mechanism. 
         FIGS. 10A-10B  illustrate a vaginal dilation device with a quick-release mechanism inserted into a female patient during labor. 
         FIGS. 11-12  illustrate the female reproductive anatomy. 
         FIGS. 13A-13B  illustrate a vaginal dilation device inserted into a female patient in both a closed and expanded configuration, respectively. 
         FIGS. 14A-14D  illustrate a vaginal dilation device inserted into a female patient during labor. 
         FIG. 15  is a chart illustrating one method of dilating vaginal tissue during labor. 
         FIG. 16  is a chart illustrating another method of dilating vaginal tissue during labor. 
         FIG. 17  is a chart illustrating another method of dilating vaginal tissue during labor. 
         FIG. 18  is a chart illustrating an additional method of dilating vaginal tissue during labor. 
         FIGS. 19A-19B  illustrate yet another embodiment of a vaginal dilation device. 
         FIGS. 20A-20D  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 21A-21C  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 22A-22E  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 23A-23B  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 24A-24C  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 25A-25C  illustrate another embodiment of a vaginal dilation device. 
         FIGS. 26A-26C  illustrate another embodiment of a vaginal dilation device. 
         FIG. 27  illustrates another embodiment of a vaginal dilation device. 
         FIG. 28  illustrates another embodiment of a vaginal dilation device. 
         FIGS. 29A-29B  illustrate another embodiment of a vaginal dilation device. 
         FIG. 30  illustrates another embodiment of a vaginal dilation device. 
         FIG. 31  illustrates another embodiment of a vaginal dilation device. 
         FIG. 32  illustrates another embodiment of a vaginal dilation device. 
         FIG. 33  illustrates another embodiment of a vaginal dilation device or a vaginal exercise device. 
         FIGS. 34A-34B  illustrate another embodiment of a vaginal dilation device or a vaginal exercise device. 
         FIG. 35  illustrates another embodiment of a vaginal dilation device or a vaginal exercise device. 
         FIG. 36  illustrates one embodiment of a cervical dilation device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The devices and methods described herein are intended to prepare and dilate vaginal tissue during labor so as to prevent pelvic floor damage, and vaginal and perineal lacerations. Some embodiments of the device can stretch the perineal tissue until the diameter of the vaginal introitus has reached a target diameter of approximately 10 cm, roughly the size of the fetal head. In some embodiments, the device is a mechanical dilator that penetrates the first 3-4 cm of the vagina, the introitus, and gradually expands the vagina from a resting diameter of 2-3 cm to a fully expanded diameter equal to the size of the delivering fetus, approximately 10 cm. Expansion can be controlled either manually or via an automatic actuation system, and the device can be quickly collapsed and removed if needed. 
     The devices described herein can be inserted during the first phase of labor and removed just prior to the second phase of labor, allowing the rest of the birthing process to proceed as normal. The device is intended to be used prior to the second phase of labor to prevent a baby from contacting the device during delivery. Depending on how long it takes to achieve full vaginal dilation to approximately 10 cm, the device can be inserted early during the first phase of labor with only very minor amounts of dilation. The dilation diameter target of 10 cm means that the device should be used in a hospital under the supervision of trained obstetricians and nurses. The device can be used without any anesthesia, or under local anesthetic. The tissue can also be prepared after administering an epidural, which would eliminate any pain or discomfort the device may cause. Local anesthesia can also be placed on the tissue contacting surfaces of the device to minimize pain. 
       FIGS. 1A-1C  illustrate one embodiment of a vaginal dilation device  100 . Vaginal dilation device  100  can include rigid or semi-rigid pads  102 , arms  104 , handle  106 , and expansion mechanism  108 . In the embodiment of  FIGS. 1A-1C , device  100  includes four sets of pads  102  and arms  104 . In other embodiments, any number of pads and arms can be used. For example, one embodiment comprises as few as 2 or 3 sets of pads and arms, and other embodiments can include more than four sets of pads and arms, such as 5, 6, 7, or even 8 or more sets of pads and arms. The sets of pads and arms can be arranged symmetrically or asymmetrically around a central axis of the device. 
     The pads  102  can be coupled to arms  104 , which can be coupled to a central rod (not shown) that extends along a longitudinal axis of the device, through the handle  106 , and is coupled to expansion mechanism  108 . The tissue contacting pads  102  can be designed to maintain stability through all dilation diameters. In some embodiments, the pads can have a saddle shape that maintains a constant waist size and pitch when expanded. These pads can be overmolded with a very compliant biocompatible elastomeric material to help evenly distribute force against the tissue and prevent trauma. Additional pad shapes and designs will be discussed below. 
     In the embodiment shown in  FIGS. 1A-1C , arms  104  comprise a scissor-like assembly, and include shafts  110  and  112  which rotate around pivot  114 . Shafts  110  and  112  can be coupled to the pads and to the central rod. In  FIGS. 1A-1C , expansion mechanism  108  comprises a mechanical knob configured to expand the arms of the vaginal dilation device. Manual rotation of the knob can cause the knob to move away from the handle and the central rod to move proximally into the handle, allowing shafts  110  and  112  to rotate around pivot  114  and push pads  102  radially outwards from the central rod of the device. Since the arms  104  comprise a scissor-like assembly, the pads  102  can remain parallel to the device and to one another during expansion, which maintains the orientation of the pads to the tissue stable during dilation. Additionally, maintaining the pads in a parallel orientation can help keep the device in place in the tissue while maximizing force distribution along the pads. 
     Rotation of the knob in the opposite direction can cause the central rod to move distally, causing the scissor-like assembly to collapse and moving the pads inwards towards the central rod. In some embodiments, the sets of arms  104  can have varying radii of curvature, which can expand the arms out at different rates if desired. 
     Although most embodiments described herein show the arms as a scissor-like assembly, it should be understood that other methods and apparatus for expanding the pads can be used. For example, the arms can be singular arms attached to the pads (e.g., similar to a speculum). 
     The vaginal dilation device can be sized, shaped, and configured to penetrate approximately the first third, or 3-4 cm, of the vagina, and to gradually expand the vaginal introitus from a resting diameter of approximately 2 cm to a fully dilated diameter of approximately 10 cm. The vaginal dilation device  100  can be configured to expand from a compact, closed configuration, as shown in  FIG. 1A , to an expanded configuration, as shown in  FIG. 1C . When the device is in the closed configuration, the pads can be seamlessly closed against each adjacent pad so as to form a solid shape (e.g., circle, oval, etc.). 
     When the device is in the closed configuration of  FIG. 1A , pads  102  can be configured to rest against each adjacent pad so as to reduce the outer diameter of the device. In some embodiments, the diameter of the pads in the closed configuration can be less than 4 cm. In one embodiment, the outer diameter of the pads in the closed configuration is approximately 2-4 cm. In other embodiments, the pads do not rest against adjacent pads in the closed configuration, but this can result in the minimum outer diameter of the pads being larger, or alternatively, in the individual pads  102  having a smaller surface area, which may lead to patient discomfort during tissue dilation. 
     As the device dilates to the expanded configuration, as shown in  FIGS. 1B-1C , pads  102  and arms  104  move radially outwards from the device, causing the pads to separate from one another. In some embodiments, the maximum diameter of the pads in the expanded configuration can be approximately 10 cm. In one embodiment, the maximum outer diameter of the pads in the expanded configuration is approximately 8-12 cm. 
     The vaginal dilation device  100  is specifically designed to promote compactness, effective dilation, and good tissue contact during expansion. As the device expands from the closed configuration to the expanded configuration, the center of mass of the device can move under the pads, as shown by arrow  116  in  FIG. 1C , which helps keep the device in place without rotating and falling out of the vagina. 
     The vaginal dilation device  100  can further comprise indicator(s) or gauge(s)  118 . In the embodiment of  FIGS. 1A-1C , the gauge  118  is disposed on handle  106 , however the gauge can be disposed in any location on the device, or even remotely from the device such as on a display monitor. In some embodiments, the gauge gives the user an indication of the diameter of the pads  102 . A user, such as a physician, can then use the gauge to know the exact amount of tissue dilation. Gauge  118  can comprise a simple binary readout (showing the diameter is above or below some threshold to continue dilating), or can have a scale showing the actual diameter of the device, for example. 
     In other embodiments, the vaginal dilation device  100  includes force sensors (not shown) configured to measure a force applied by the pads against tissue, or alternatively, to measure a force applied against the pads, and the gauge  118  can give the user an indication of the measured force. The force sensors can be strain gauges, whetstone bridges, piezoelectric crystals, hydraulic/pneumatic load cells, elastic devices, or any other force sensor or force transducer known in the art. Gauge  118  can comprise a simple binary readout (showing the force is above or below some threshold to continue dilating), or can have a scale showing the actual force being applied to the tissue, for example. In additional embodiments, gauge  118  can indicate both a diameter of the pads and a force sensed by the pads. Alternatively, the vaginal dilation device can comprise multiple gauges, including diameter gauges and force gauges. 
     The dilation device may additionally include a quick-release mechanism configured to collapse the device from the expanded configuration to the closed configuration. The quick-release mechanism can comprise bump-release  120  and quick-release lever  122 . Additional details regarding the quick-release mechanism will be discussed below. 
       FIG. 1D  illustrates one embodiment similar to the device of  FIGS. 1A-1C , however the expansion mechanism  108  of  FIG. 1D  remotely coupled to the rest of the device (e.g., remotely coupled to the central shaft, arms, and pads) via flexible assembly or flexible tube  109 . The device of  FIG. 1D  operates in the same manner as the device described above in  FIGS. 1A-1C , however the remote expansion mechanism allows a user to expand/dilate the device from a distance away from the patient. This is advantageous because during labor, the patient&#39;s legs are typically covered with sheets or a blanket, so the remote expansion mechanism allows for actuation of the device without having to remove the covers, protecting the patient&#39;s privacy. 
     In other embodiments, the device can include an alarm or alert mechanism, such as a visual alert (e.g., a light, or a warning indicator on a display) or an audible alert (e.g., a buzzer or an alarm sound) to indicate to a user that the device is applying too much, or too little force to the vagina. The alert mechanism can also include a timer configured to alert the user (e.g., by an audible or visual signal) when to dilate the device. 
       FIG. 2  is a cutaway view of a vaginal dilation device  200  in an expanded configuration, showing the operation of a diameter gauge  218  according to one embodiment. Vaginal dilation device  200  is a variation of the vaginal dilation device  100  described above.  FIG. 2  illustrates the interior of handle  206 , including expansion mechanism  208 , diameter gauge  218 , central rod  224 , spring  226 , and nut  228 . Rotation of the expansion mechanism can cause central rod  224  to move proximally into the handle, which in turn causes nut  228  to move proximally to compress spring  226 . As the spring is compressed, it can apply pressure to the diameter gauge  218 , causing it to move according to the diameter of the pads  202  and arms  204  as they expand radially outwards. Since the outward movement of a scissor-like mechanism as shown in  FIG. 2  is not linear, the vaginal dilation device may further include a diameter gauge amplifying mechanism  230 , such as an additional spring coupled to a rotating portion of the gauge, to provide a more linear read out for the diameter gauge  218 . 
     The tip of gauge  218  may extend out through a window in the handle  206 . In some embodiments, the handle can include indicator marks or diameter measurements along the length of the window to provide an indication to the user of the diameter of the device. The marks can be colors, such as green, yellow, red, to give an indication of the amount of dilation, or can be accurate diameter measurements, such as marks indicating 0-10 cm of dilation. Other marks or indicators can also be used, as long as they give an approximate or accurate read-out of the diameter of the device as it expands. 
       FIGS. 3A-3B  show cross-sectional views of another embodiment of a vaginal dilation device  300 . The vaginal dilation devices described above in  FIGS. 1 and 2  were directed to a device actuated by manual rotation of a knob. However, the vaginal dilation device  300  of  FIGS. 3A-3B  can include an actuation mechanism that comprises a constant force device  332  and a button  336  to actuate expansion of the device. In the embodiment shown in  FIGS. 3A-3B , the constant force device  332  comprises a spring. However, any similar stored energy device can be used in place of the spring, including a pump or a piston, an elastic band, or gears, for example. 
     The vaginal dilation device of  FIGS. 3A-3B  can include arms  304 , handle  306 , gauge  318 , central rod  324 , shuttle assembly  325 , rack assembly  334 , button  336 , and pad supports  340 . In the embodiment of  FIGS. 3A-3B , button  336  can be coupled to a pin  338 . Pad supports are configured to support pads, such as pads  102  or  202  described above. It should be understood that button  336  could be any other form of actuating device, such as a lever, a trigger, or a rotating dial, for example. 
     Referring still to  FIGS. 3A-3B , the operation of vaginal dilation device  300  will now be described. As shown, arms  304  can comprise a scissor-like assembly. A proximal portion of the scissor-like assemblies can be coupled to the handle  306 , and a distal portion of the scissor-like assemblies can be coupled to shuttle assembly  325 . Central rod  324  can extend from shuttle assembly  325  along a longitudinal axis of the device into handle  306 , terminating at rack assembly  334 . Constant force device  332 , such as a spring, can be disposed inside the handle around the central rod, compressed between an inner wall of the handle and the rack assembly. The rack assembly can comprise a plurality of gears or teeth, which can engage pin  338  of button  336 . 
     When button  336  is depressed, pin  338  disengages rack assembly  334 . Constant force device  332  (e.g., a spring) is then allowed to decompress and expand, thereby applying a constant force against the rack assembly and the central rod  324 , and thus shuttle assembly  325 , proximally towards handle  306 . As the distance between shuttle assembly  325  and handle  306  decreases, the scissor-like assemblies expand, pushing pad supports and pads (not shown) radially outward from the device. It should also be understood that device  300  of  FIGS. 3A-3B  can comprise an actuation mechanism remotely coupled to the device (e.g., via a flexible tube as shown in  FIG. 1D ) so as to allow for expansion of the device from a location remote from or a distance away from the patient. 
     As the constant force device  332  pushes against rack assembly  334  and central rod  324 , gauge  318  moves proximally with the rack assembly, giving the user an indication of the dilation diameter of the pads of the vaginal dilation device. Expansion of the device continues until the next tooth or gear in the rack assembly engages pin  338  of button  336 . The teeth of rack assembly  334  can be spaced at specific increments of dilation, for example, spaced 1 cm apart along the desired range of dilation, such as from 1 cm to 10 cm. Once the rack assembly has re-engaged pin  338 , the user can again depress button  336  to initiate the next interval of dilation. In some embodiments, the button can also remain in the pushed “on” position, which would allow the device to continue expanding and dilating tissue with a constant force. Similarly, in another embodiment, the rack assembly can include only a single tooth or gear, allowing the device to continue to expand at a constant force once the pin  338  has disengaged the single tooth. 
     Since the vaginal dilation device is configured to expand at a constant force, the amount of force applied by the device to tissue can be determined and controlled so as to maximize effectiveness of the device and prevent the device itself from causing tissue damage. The constant force can be set at a level to reduce the risk of causing trauma, yet be enough to successfully, controllably dilate the tissue. In another embodiment, the vaginal dilation device can include a clutching mechanism, such as another spring or a torque-wrench type mechanism to prevent over-expansion of the pads. The clutching mechanism can be configured to engage at a preset force threshold to prevent the device from applying a force higher than the force threshold to tissue. In other embodiments, the device can include an alarm or alert mechanism, such as a visual alert (e.g., a light, or a warning indicator on a display) or an audible alert (e.g., a buzzer or an alarm sound) to indicate to a user that the device is applying too much, or too little force to the vagina. The alert mechanism can also include a timer configured to alert the user (e.g., by an audible or visual signal) when to dilate the device. 
     As described above, the constant force device  332  can comprise any device configured to apply a constant force, such as a spring, a piston, or a pump. The constant force device can be configured to automatically apply a constant force of any desired amount from the pads of the device to tissue. In some embodiments, the constant force device can apply a constant force to tissue ranging from approximately less than 10 lbs. of force. In some embodiments where a spring is used as the constant force device, the spring coils can have a variable thickness in order to adjust for gains in mechanical advantage as the vaginal dilation device is expanded, thus keeping the force applied by the device to tissue as a constant. 
       FIGS. 3A-3B  also illustrate the mechanisms that allow the pads and pad supports  340  to remain parallel as the device expands. Arms  304  can include a rotating pivot point  342  configured to slide in slot  343  as the device expands. Movement of the pivot point along the slot allows the pads to remain parallel to the central rod of the device during tissue dilation. 
       FIGS. 20A-20D  illustrate another embodiment of a mechanism configured to allow pads  2002  to remain parallel as device  2000  expands. Referring to  FIGS. 20A-20C , pads  2002  can connect to arms  2004  at pivot  2006 . Spring  2008  can be configured to push against pads  2002 . As the device  200  expands, the load against the pads increases, compressing the spring. The spring can be configured to provide enough force to overcome any initial load applied against the pads by the tissue. Thus, the spring can be chosen that has a rate to allow the pads to remain parallel as the device expands.  FIG. 20D  illustrates the device in an expanded configuration, with the springs  2008  pushing against pads  2002  to cause the pads to remain parallel. The device illustrated in  FIGS. 20A-20D  can be configured for use as a vaginal dilator device or as a vaginal exercise device. 
     In another embodiment, as shown in  FIGS. 3C-3D , the vaginal dilation device comprises a constant force mechanism  332 , such as the spring described above, and further includes a force adjustment mechanism  344  configured to change the amount of force that the constant force mechanism, and thus the vaginal dilation device, applies to tissue. As shown in  FIGS. 3C-3D , the force adjustment mechanism  344  can comprise a wheel or knob positioned adjacent to the spring. When the force adjustment mechanism is adjusted from a minimum position, as shown in  FIG. 3C , to a tensioned position, as shown in  FIG. 3D , the force adjustment mechanism compresses the spring, and adds force to which the spring will push back against the rack mechanism, thereby increasing the force the vaginal dilation device can apply to tissue. 
     In some embodiments, the vaginal dilation device of  FIGS. 3A-3D  can include a dampener (not shown), to limit any rapid dilation caused by the device. The dampener can be a piece of foam, a spring, or a piston mechanism at the proximal end of the device, for example. 
       FIG. 21A-21C  illustrate another embodiment of a vaginal dilation device  2100 , including a cam  2102  configured to normalize the force curve of arms  2104  as they expand. Certain features of a vaginal dilation device not illustrated in  FIGS. 21A-21C  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . Referring to  FIG. 21A , vaginal dilation device  2100  can include arms  2104  (e.g., a scissor-like mechanism) coupled to central rod  2106  and shuttle assembly  2108 . Cam  2102  can be coupled to the central rod, and can be in contact with wheel  2110 . The device can further include a constant force device (not shown in  FIG. 21A ) similar in function and operation to constant force device  332  described above in  FIGS. 3A-3D . As the constant force device pulls central rod  2106  and shuttle assembly  2108  in the direction indicated by arrow  2112  to expand device  2100 , cam  2102  pivots along wheel  2110 . In a vaginal dilation device utilizing a scissor-like expansion mechanism, the device requires more force to expand at the beginning of expansion than at the end of expansion (e.g., the vaginal dilation device requires more force to expand from 1 cm to 2 cm than it does to expand from 9 cm to 10 cm). This is because a scissor-like expansion mechanism gains mechanical advantage during expansion. The cam  2102  of  FIGS. 21A-21C  can be configured to linearize the force of vaginal dilation device  2100  during expansion. To do so, the cam  2102  can be designed to lose mechanical advantage at the same rate that the scissor-like arms  2104  gain mechanical advantage during expansion. For example, in one embodiment, a particular angular change in the cam  2102  can lead to a corresponding change in diameter of the pads and arms  2104  of the dilation device  2100 . 
       FIG. 21B  illustrates a cam  2102  comprising a diameter gauge  2114 , wherein the diameter gauge is configured to display a diameter of the vaginal dilation device.  FIG. 21C  illustrates another embodiment of a cam  2102  including mechanical stops, rests, or detents to provide feedback during the expansion process. In one embodiment, shown in  FIG. 21C , stops can be placed along the cam  2102  corresponding to a pre-set device diameter. Thus, in  FIG. 21C , the stops are located at centimeter intervals ranging from 3 cm-10 cm (e.g., a stop is placed at positions on the cam corresponding to device expansion diameters of 3 cm, 4 cm, 5 cm . . . 10 cm). In some embodiments, the stops on cam  2102  can prevent the vaginal dilation device from over-expanding without input from a user. 
       FIGS. 22A-22E  illustrate additional embodiments for overcoming low angle forces of a scissor-like expansion mechanism in a vaginal dilation device  2200 . Certain features of a vaginal dilation device not illustrated in  FIGS. 22A-22C  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . In the embodiment of  FIGS. 22A-22C , lever  2202  can be pivotably coupled to central rod  2206 , and the lever can be configured to engage a detent or bump  2208  on arm  2204 . As the dilation device expands and central rod  2206  moves towards a proximal end of the device, lever  2202  provides additional mechanical advantage to arms  2204  because it is at a greater angle relative to the central rod than the arms of the device.  FIG. 22B  illustrates the lever  2202  fully expanded as the dilation device and arms  2204  continue to expand. Referring now to  FIG. 22C , the arms  2204  of the dilation device have expanded beyond the point of lever  2202  engaging detent  2208 , so that the lever floats freely and the arms are allowed to expand on their own. The lever can continue to float until the arms collapse back to a point at which the lever can once again engage the detent  2208 . 
       FIGS. 22D-22E  illustrate a similar concept to the device illustrated in  FIGS. 22A-22C . Certain features of a vaginal dilation device not illustrated in  FIGS. 22D-21E  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . In  FIGS. 22D-22E , the central rod  2206  can include a detent or bump  2202  instead of a lever, and the detent  2202  can be configured to engage a corresponding detent or bump  2208  on the arms  2204 . This interaction between the detents  2202  and  2208  provides additional mechanical advantage to arms  2204  during the initial stages of expansion. Once the arms are sufficiently expanded to the point where the detents are not contacting another, as shown in  FIG. 22D , the scissor-like mechanism can continue to expand like normal. 
       FIGS. 23A-B  illustrate another embodiment of a vaginal dilation device  2300  comprising an adjustable force mechanism. Certain features of a vaginal dilation device not illustrated in  FIGS. 23A-23B  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . Referring to  FIG. 23A , dilation device  2300  comprises force mechanism  2302  (e.g., a spring), arms  2304 , central rod  2306 , force adjustment mechanism  2308 , target diameter gauge  2310 , and actual diameter gauge  2312 . The device can operate in a manner similar to the device described herein, namely, the force mechanism  2302  pulls against central rod  2306 , which causes arms  2304  to expand outward and increase the diameter of the device. In the embodiment shown in  FIG. 23A , force adjustment mechanism  2308  can be used to change the compression of force mechanism  2302 . In some embodiments, force mechanism  2308  is coupled to a target diameter gauge  2310 , which is configured to display a target diameter of dilation based on the current compression setting of force mechanism  2302 . Actual diameter gauge  2312  can be configured to display the actual dilation diameter of the device. For example, if the vaginal dilation device  2300  is inserted into a patient, and has achieved a maximum dilation for that particular force setting, a user can adjust the force setting of force mechanism  2302  with adjustment mechanism  2308  to increase or decrease the diameter of the device. The desired diameter can be dialed in according to target diameter gauge  2310 , and the user can monitor the progress of the device with actual diameter gauge  2312 . 
       FIG. 23B  is another embodiment of an adjustable force mechanism for use with a vaginal dilation device. Certain features of a vaginal dilation device not illustrated in  FIG. 23B  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . Instead of changing the compression of a force mechanism (e.g., a spring) as in the embodiment of  FIG. 23A , in this embodiment, force mechanism  2302  can be translated up and down lever  2314  by rotating adjustment mechanism  2308 . Adjusting the location of the force mechanism along the lever acts like changing the point of a fulcrum on a lever, which can adjust the amount of force the force mechanism applies to the device. Thus, a user can monitor the actual diameter gauge (not shown) and the force gauge  2310 , and adjust the position of the force mechanism according to a desired diameter or force of the device. 
       FIGS. 24A-24C  illustrate another embodiment of a vaginal dilation device  2400 , including a ratcheted cam  2403 . Certain features of a vaginal dilation device not illustrated in  FIGS. 24A-24C  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . Similar to the embodiments described above that employ a cam, the ratcheted cam of this embodiment can linearize the force needed to expand the device. In this embodiment, force mechanism  2402  can push against rack  2410 , which engages ratcheted cam  2403 . This causes central rode  2406  to move proximally towards the ratcheted cam, which expands arms  2404  and dilates the device outwardly. Force adjustment mechanism  2408  can be configured to change the compression of force mechanism  2402 , as described above. 
       FIGS. 24B-C  illustrate additional ways of adjusting the force applied by the device, similar to the embodiment described above in  FIG. 23B . In  FIG. 24B , force adjustment mechanism  2408  can be configured to adjust a pivot point  2412  of the device. The pivot point can then be connected to the central rod (not shown, but described above) to facilitate expansion of the device. In  FIG. 24C , the pivot point  2412  is fixed, so the force adjustment mechanism  2408  is configured to adjust the position of the force mechanism  2402  relative to the pivot point (similar to the fulcrum embodiment described above in  FIG. 23B ). 
       FIGS. 25A-25C  illustrate another embodiment of a vaginal dilation device comprising a ratcheted cam with multiple gears. Certain features of a vaginal dilation device not illustrated in  FIGS. 25A-25C  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . Similar to the embodiment of  FIGS. 24A-24C , force mechanism  2502  can be configured to apply pressure to rack  2510 , which engages ratcheted cam  2510  of the device, causing scissor-like arms (not shown) to expand outwardly from a central rod of the device. In this embodiment, the ratcheted cam can include multiple gears, such as gears  2503   a  and  2503   b  having varying diameters. Referring to the side views of cam  2503  and rack  2510  in  FIG. 25C , it can be seen that rack  2510  can include multiple levels configured to align with the various gears of the ratcheted cam. Using multiple gears allows a user to change the amount of force applied to the arms of the device. For example, smaller gear  2503   b  requires more force to expand the arms of the dilation device than larger gear  2503   a . Engaging the different gears can be implemented in a number of ways. In one embodiment, the ratcheted cam  2503  can be pushed laterally (e.g., in the direction of arrow  2512 ) to change from smaller gear  2503   b  to larger gear  2503   a . Although the embodiment of  FIGS. 25A-25C  illustrates only two gears, it should be understood that any number of gears can be used. 
       FIGS. 26A-26C  illustrate various embodiments of a constant force spring that can be used in a vaginal dilation device. Certain features of a vaginal dilation device not illustrated in  FIGS. 26A-26C  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . The constant force spring illustrated in  FIGS. 26A-26C  can be used, for example, as the constant force mechanism  332  of  FIGS. 3C-3D  above.  FIG. 26A  illustrates back, side, and front views, respectively, of a constant force mechanism  2632 , comprising a cam  2603 , a clock spring  2602 , a target diameter gauge  2608 , and a dial  2610 . Ratchet features disposed on the dial (not shown) can prevent the dial from unwinding. The spring would then be configured to transmit force from the cam  2603  through a central rod (not shown, but similar in function to the central rods described above), which would then expand arms of the vaginal dilation device. The embodiment of  FIG. 26A  could also include an actual diameter gauge (not shown) in addition to the target diameter gauge. 
       FIGS. 26B-26C  illustrate various embodiments for adjusting the force of the clock spring  2602  of  FIG. 26A . In  FIG. 26B , force adjustment mechanism  2612  can adjust a pivot point of lever  2614 , which changes the compression of clock spring  2602 . In  FIG. 26C , force adjustment mechanism  2612  compresses the spring directly, causing an increase or decrease in the force applied by the spring to the cam. 
       FIG. 27  illustrates another embodiment of a constant force vaginal dilation device  2700 . In  FIG. 27 , the vaginal dilation device includes a series of cylinders  2702   a - d  slidably connected to central rod  2706 . The cylinders can be separated by compression springs  2704   a - d . Flexible arch features  2706   a - b  (e.g., leaf springs, living hinges) can also span from one cylinder to the next. When the system is compressed, the arches bend and the device expands in diameter. A dial feature  2708  can house a hard stop  2710  for each cylinder (only one hard stop is illustrated in  FIG. 27 ). Engaging a particular hard stop on the dial locks out a corresponding spring(s). The force required to compress the system becomes greater with each spring that is locked out. As shown in the front view of dial  2708  in  FIG. 27 , the dial can include a number of user actuatable hard stops corresponding to various springs, and thus, various forces. For example, in one embodiment, the dial includes force settings of 1 lb., 2 lbs., 3 lbs., and 4 lbs., corresponding to actuating each of the hard stops  2710 . It should be understood that other forces and number of hard stops/springs can be used in other embodiments. 
       FIG. 28  illustrates another embodiment of a vaginal dilation device  2800 , comprising a stent or yurt-like design. In  FIG. 28 , the device can comprise a plurality of scissor-like stent features  2802  that are pre-biased to expand. When the device is inserted into tissue, for example into the vagina, the stent features can automatically expand to cause the device to increase in diameter. In some embodiments, the stent features  2802  comprise a shape memory material, such as nitinol. The stent features can be configured to expand at a preset force, depending on the application and the maximum diameter desired. In some embodiments, the device can include a diameter gauge  2804  configured to display a diameter of the device. The device of  FIG. 28  provides open access to the interior of the device, allowing a physician or user to gain access to the body cavity being dilated. 
       FIGS. 29A-29B  illustrate another embodiment of a vaginal dilation device  2900 , utilizing a simplified expansion mechanism to replace the scissor-like mechanisms described above. In  FIG. 29A , a force mechanism  2902  (e.g., a spring) can apply a force to arm  2904 , which pivots against central rod  2906 . Arm  2904  can also pivotably connect to V-shaped mechanism  2908 , which also pivots against the central rod. As the spring expands and applies force against arm  2904 , it pivots against the central rod and expands V-shaped mechanism  2908 . Expansion of the arm  2904  and V-shaped mechanism can cause the vaginal dilation device to expand, for example, by pushing pads  2910  outward.  FIG. 29B  illustrates how adjustment of dial  2912  in either direction can cause the spring to shuttle in both directions along the central arm, thereby adjusting the force applied by the force mechanism to the arm. 
       FIG. 30  illustrates yet another embodiment of a vaginal dilation device  3000 , including a simplified expansion mechanism. The embodiment of  FIG. 30  includes a rotating array  3002  comprising a plurality of spring plungers  3004 . In some embodiments, each spring plunger applies a different force to a surface  3006  of the device. For example, referring to  FIG. 30 , each of the four spring plungers  3004  can have a different strength spring to apply a different force to the device. The rotating array can be rotated to change which spring plunger comes into contact with the surface of the device. As shown in  FIG. 30 , the spring plungers can have varying thicknesses to determine how much force is exerted by the spring. When the spring plunger exerts a force against surface  3006 , the device can pivot at pivot point  3008 , allowing pads  3010  to expand outwards from the device to dilate tissue. 
       FIGS. 4A-4B  show cross-sectional views of an automated vaginal dilation device  400 . In contrast to the manual or semi-automated devices above, vaginal dilation device  400  can comprise a semi-automated or fully-automated actuation mechanism  408  comprising a controller  448  coupled to a motor  454  within the device and configured to automatically dilate, expand, and contract the pads and arms. Automated vaginal dilation device  400  can comprise pads  402 , arms  404 , handle  406 , diameter sensor  418 , central rod  424 , force sensors  446 , controller  448 , receiver  450 , transmitter  452 , motor  454 , and worm gear  456 . Pads  402  and arms  404  move mechanically in a manner similar to that described above in  FIGS. 1-3 . 
     In  FIGS. 4A-4B , controller  448  (e.g., a computer comprising hardware and software configured) can communicate with vaginal dilation device either wirelessly, via receiver  450  and transmitter  452 , or by wire (not shown). The vaginal dilation device can measure a force applied by pads  402  to tissue, or alternatively, can measure a force applied against the pads, and transmit the measured force to controller  448  (e.g., either wirelessly or by wire). The controller  448  can be configured to automatically move the arms  404  and the pads  402  radially outwards based on the force measured by the force sensor. 
     For example, hardware and software installed in controller can drive motor  454  based on the measured force. Motor  454  can include a threaded shaft  455 , which can engage a rack assembly disposed on central rod  424 . When the motor  454  is actuated by controller  448 , the threaded shaft  455  can control movement of the central rod, causing the arms and pads to expand and contract away and towards the central rod of the device. In some embodiments, motor  454  can be replaced with a pump or a computer actuated piston, for example. 
     Motor  454  can also be attached to a second threaded shaft  456 , which can engage gears on diameter sensor  418 . As the motor actuates the vaginal dilation device to expand or contract, the second threaded shaft can engage and rotate sensor  418  to indicate the diameter of the device. The measured diameter of the device can also be transmitted to controller  448  as an analog or digital signal (e.g., either wirelessly or by wire). 
     In other embodiments, the vaginal dilation device can include an alarm or alert mechanism, such as a visual alert (e.g., a light, or a warning indicator on a display) or an audible alert (e.g., a buzzer or an alarm sound) to indicate to a user that the device is applying too much, or too little force to the vagina. The alert mechanism can also include a timer configured to alert the user or the controller (e.g., by an audible or visual signal or by an input to the controller) when to dilate the device. 
     Many modes of operation are possible with the vaginal dilation device shown in  FIGS. 4A-4B . For example, controller  448  can be configured to actuate motor  454  to dilate the device outwards at a constant force (e.g., a predetermined constant of approximately less than 10 lbs. of force). In another embodiment, the controller  448  can be configured to actuate motor  454  to dilate the device outwards at a time-varying force. For example, the controller can be configured to actuate motor  454  to dilate the device until the force applied by the device to tissue approaches a force threshold. 
     In another embodiment, a physician may initially want to dilate the vaginal tissue at a first constant force. The first constant force may be low, such less than 3 lbs. of force. After a set period of time has passed, the controller can be configured to automatically stop dilating tissue until receiving more instructions from the user, or alternatively, the controller can be configured to automatically dilate the vaginal tissue at a second constant force. The second constant force may be different than the first constant force, such as approximately 3-5 lbs. of force. In this embodiment, the vaginal dilation device  400  can automatically dilate tissue at a constant force for a set period of time, and then can either stop dilating tissue or continue to dilate at a second constant force. The controller can be configured to automatically adjust the force applied by the device to the tissue (e.g., either raise or lower the constant force) until the device achieves the desired amount of tissue dilation (e.g., 10 cm of dilation). 
     In another embodiment, the vaginal dilation device does not automatically dilate for a set period of time, but rather, the vaginal dilation device is configured to automatically expand and dilate tissue until a threshold force is reached (as measured by sensors  446 ). For example, a physician or the controller may set a threshold force of approximately 3 lbs. of force. The vaginal dilation device can then be configured to automatically dilate vaginal tissue until sensors  446  measure a force greater than or equal to the threshold force of 3 lbs. of force, at which point the device would automatically stop dilating the tissue. It should be understood that in other embodiments, the threshold force can be any force and is not limited to 3 lbs. 
     In yet another embodiment, the controller can be configured to actuate the vaginal dilation device to expand until a threshold force is measured, and the controller can automatically actuate the device to contract slightly upon reaching the threshold force so as to allow the vaginal tissues to relax, and thus allow the force applied by the device to the tissue to decrease. 
     In yet an additional embodiment, the controller can be configured to actuate the vaginal dilation device based on a sensed diameter of the device, or alternatively, based on a sensed force and a sensed diameter of the device. The diameter can be measured or sensed with diameter sensor  418 . In some embodiments, the controller can be configured to dilate the device until the device reaches a preset diameter. In other embodiments, the controller can be configured to actuate the device at a first force until the device reaches a first diameter, and then to actuate the device at a second force until the device reaches a second diameter. For example, the controller can actuate the device at a force of 3 lbs. until the device reaches a diameter of 3 cm. Upon dilating to 3 cm, the controller can then automatically actuate the device at a force of 4 lbs. until the device reaches a diameter of 4 cm. This process of varying the force applied until preset diameters are reached can be continued until the target dilation diameter is achieved. 
       FIG. 31  illustrates another embodiment of a vaginal dilation device  3100 , comprising a cam and a motor configured to automatically oscillate the device. Certain features of a vaginal dilation device not illustrated in  FIG. 31  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-3 . The device functions similar to the cammed vaginal dilation device of  FIGS. 21A-21C . In operation, motor  3102  can include an offset wheel which rotates against cam  3104 , causing the arms (not shown) and pads (not shown) of the vaginal dilation device to oscillate. The arms and pads, and thus the device, can then oscillate radially inward and outward as described herein in other embodiments, either to promote tissue relaxation and dilation or to prevent pain. 
       FIG. 32  describes another embodiment of a vaginal dilation device  3200  utilizing a motor  3202  and a barrel cam  3204  to normalize a force curve of the device as it expands. Certain features of a vaginal dilation device not illustrated in  FIG. 32  can be found in other illustrations of vaginal devices described herein, specifically  FIGS. 1-4 . A barrel cam with a variable pitch groove can compensate for the varying force curve found in devices with a scissor-like expansion mechanism  3203 . The pitch of the cam groove can be high at the start of a device expansion and decrease as the device progresses towards full expansion at the end. This means the barrel cam would lose mechanical advantage at the same rate the scissor mechanism gains it. 
     A motor driving the barrel cam would see a constant load. Adding a clutch  3206  with adjustable preload  3208  between the motor and barrel cam would allow the user to control how much force is transmitted to the scissor mechanism. The clutch could act as a failsafe, preventing the device from “running away” and opening uncontrollably. In some embodiments, irregularities or “bumps” could be added to the cam groove to cause the scissor mechanism to oscillate during expansion. 
       FIGS. 5A-5D  illustrate various embodiments of pad shapes for use with a vaginal dilation device. The pads described herein can be covered by a soft atraumatic material made of a foam, silicone, or other rubber or gel like material. Pads  502  typically have a “saddle” shape, wherein both the distal and proximal portions of the pads are raised so as to cradle and conform to the vaginal tissue. The distal or anterior curve may better conform to the natural shape of the anatomy in order to more effectively distribute the force and provide greater stability. The proximal or posterior curve can resemble a “heel” shape to help keep the device from sliding out of the patient. As the vaginal dilation device expands and engages tissue, the tissue may slide slightly on the pad. However, the contacting surface of the introitus will remain in the “valley” of the pads. In some embodiments, such as those shown in  FIGS. 5B-5C , the pads can include notches or raise portions in an intermediate area of the pad to further conform to or engage the anatomy. In other embodiments, the pads may include slits to avoid putting pressure on the anterior or posterior anatomy. 
     In additional embodiments, springs can be incorporated into or below the pads. These springs can keep the force of the pad on the tissue within a particular range to keep a user from over dilating the device. For example, springs incorporated into or below the pads may apply a constant force against the pads, similar to the constant force device described above in  FIG. 3 . In yet an additional embodiment, the device or the pads may further include an automatic oscillation mechanism configured to prevent pressure necrosis. For example, springs or other similar devices on or under the pads can be configured to automatically oscillate to reduce pressure applied to the tissue. In addition, the pads can include heating or vibrating elements to increase tissue relaxation. 
       FIGS. 6A-6G  illustrate various embodiments of force sensors disposed on or in a vaginal dilation device. In  FIG. 6A , force sensor  646  is disposed on a surface of pad  602 . In  FIG. 6B , force sensor  646  is disposed below a surface of pad  602 . In  FIG. 6C , force sensor  646  is disposed on a surface of pad support  640 , below pad  602 . In  FIG. 6D , multiple force sensors  646  are disposed below a surface of pad  602 . In  FIG. 6E , multiple force sensors  646  are disposed on a surface of pad support  640 , below pad  602 .  FIG. 6F  illustrates on embodiment of a vaginal dilation device  600 , including both a diameter gauge  618   a  and a force gauge  618   b , as well as force sensors  646  disposed on pads  602 . In  FIG. 6G , force sensor  646  is positioned proximally from arms  604 . When arms  604  and pads  602  expand to dilate tissue, the arms can apply pressure to  646 , which can measure the applied force. 
       FIGS. 7A-7B  show embodiments of a vaginal dilation device  700  covered with a protective sheath  758 , to create an expandable sterile barrier to prevent infection prior to and after delivery. The protective sheath can be an elastic material, such as latex, silicon, etc. In some embodiments, the sheath could also be made from a non-elastic material that is folded in and around the device, and unfolds as the device is expanded. 
       FIGS. 8A-8D  illustrate various embodiments of a vaginal dilation device  800  comprising working channels or through-ports. In  FIG. 8A , device  800  includes a through-port  860  through which a user can insert other devices such as cervical monitoring devices, scopes, fetal monitoring devices, or cervical dilating devices. In addition, other commonly used tools such as air, water, suction, surgical cutting devices, ultrasound or other imaging devices, etc can be inserted into the through port. In  FIGS. 8B-8C , vaginal dilation device  800  can include a flexible working channel  862 . The working channel can comprise a flexible, bendable material, and can accommodate any of the devices described above. In  FIG. 8B , the working channel can be routed through the handle of the vaginal dilation device and out through a central axis of the pads  802 . In  FIG. 8C , the working channel can be routed along the side of the handle of the device, through the open space between the pads when they are expanded.  FIG. 8D  illustrates the working channel routed along the side of the handle and through the open space between pads  802 , extending out through a protective sheath  858 . There could be seals around the working channels and through-ports of  FIGS. 8A-8D  to keep the anatomy sterile. The working channels or through-ports can incorporate a one way valve to allow removal of fluids or tissue without allowing bacteria or other particles to enter the patient. 
       FIG. 9  illustrates a vaginal dilation device  100  having a quick-release mechanism. The quick-release mechanism can comprise bump-release  120 , quick-release lever  122 , and quick-release pin  164 . The device shown in  FIG. 9  is a simplified version of the device  100  described above, and includes central rod  124  and shuttle assembly  125 . The description relating to the quick-release mechanism can be applied to any of the vaginal dilation devices described herein. 
     In situations where the vaginal dilation device  100  needs to be removed from the patient quickly, quick-release lever  122  can be pulled or flipped to and contract the device back to a near closed configuration. This feature allows the user to quickly stop the device from applying force to the tissue, and prevents tissue from being pinched during a quick retraction. When quick-release lever  122  is actuated, it releases a spacer which allows central rod  124  to move distally away from the handle  106  of the device. This moves shuttle assembly  125  away from the handle which changes the angle of the arms and moves the pads (not shown) towards the central rod of the device. 
       FIGS. 10A-10B  illustrate a vaginal dilation device  100  having a quick-release mechanism in use. In  FIG. 10A , the device  100  is shown inserted into the patient&#39;s vagina as the fetus is near delivery. Ideally, the device can be removed prior to the fetus breaching the cervix, so the user can actuate quick-release lever  122  to collapse the device into the closed configuration for removal. However, in some instances, the fetus may enter the vaginal canal with the device  100  still in place. In this situation, the fetus can engage the bump-release  120 , as shown in  FIG. 10B , to collapse the device into the closed configuration for easy removal. In some embodiments, actuation of the bump-release can trigger an alarm or visual/audible signal to alert a physician that the fetus has contacted the device. 
       FIGS. 11-12  illustrate the bones and surround tissues of the female reproductive anatomy. The pelvic floor is defined by the pubococcygeus-puborectalis muscle complex PC, which forms a V-shaped sling running from the either pelvic sidewall anteriorly, and posteriorly around the anorectal junction. The levator hiatus is the V-shaped space between the muscular walls. Inside this V shape lies the urethra U (anteriorly), the vaginal canal VC (centrally) and the anus A (posteriorly). The area of the levator hiatus in young nulliparous (women who have never given birth) women varies from 6 to 36 cm2 on Valsalva manoeuvre. The bones surrounding the pelvic region, including the Pubic Sympisus, the Pubic Crest, and the Ischium, can also be seen in  FIGS. 11-12 . 
     The area of the average fetal head in the plane of minimal diameters measures 70-100 cm′ (equating to a head circumference of 300-350 mm), requiring marked distension and deformation of the levator complex. It has been shown with the help of MRI-based computer modeling that the most inferior and medial parts of the levator complex have to increase in length by a factor of 3.26 during crowning of the fetal head. Given this degree of acute distension, it is remarkable that severe muscular trauma is not even more prevalent, as such stretch is commonly thought to be well beyond the approximately 150% elastic limits of tissue strain. 
       FIGS. 13A-13B  illustrate a vaginal dilation device  100  inserted into a female patient in both a closed and expanded configuration, respectively. The vaginal dilation device of  FIGS. 13A-13B  can be any vaginal dilation device described herein. In  FIG. 13A , the device  100  is shown inserted into the vagina in a closed configuration. The outer diameter of the device in the closed configuration can be less than 4 cm to increase patient comfort.  FIG. 13B  illustrates device  100  inserted into the vagina in an expanded configuration. The outer diameter of the device in the expanded configuration can be up to approximately 10 cm. The orientation of pads  102  with respect to the anatomy is also shown. In  FIG. 13B , vaginal dilation device  100  includes four pads  102 . When the pads are expanded, the pads avoid placing pressure on critical parts of the anatomy, such as the urethra U and the perineum and anus A. In other embodiments where more than four pads are incorporated in the device, the device does not include pads that expand directly upwards (to avoid putting pressure on the urethra) or directly downwards (to avoid putting pressure on the perineum and anus). 
     Methods of using a vaginal dilation device will now be described.  FIGS. 14A-14D  illustrate a vaginal dilation device inserted into a female patient during labor. The vaginal dilation device described in these methods can be any vaginal dilation device described herein, including the fully manual vaginal dilation device of  FIGS. 1-2 , the semi-automated vaginal dilation device of  FIG. 3 , or the fully semi or fully-automated vaginal dilation device of  FIG. 4 . In addition, the vaginal dilation device shown in  FIGS. 14A-14D  may include any of the additional features described herein, including force sensors, diameter gauges/sensors, working channels, protective sheaths, etc. 
     In  FIG. 14A , vaginal dilation device  1400  is shown inserted into the vagina of a patient and can include pads  1402 , actuation mechanism  1408 , diameter gauge  1418   a , and force gauge  1418   b . The device can include sensors for measuring force and/or diameter, not shown, but described above. In the embodiment of  FIG. 14A , the device is shown with an actuation mechanism comprising a mechanical knob, but it should be understood that in other embodiments, the actuation mechanism can comprise a constant force device such as a spring, or a fully automated system such as a controller and a motor. The device  1400  of  FIG. 14A  is shown in a closed or compact configuration. The device can be inserted into the patient any time during the first phase of labor, typically when the patient arrives at the hospital prior to giving birth. On average, a woman spends 14 hours in a hospital until the second phase of labor begins. Diameter gauge  1418   a  can give an indication of the outer diameter of the pads of the device, to indicate how far the vaginal tissue has dilated. Force gauge  1418   b  can indicate the amount of force being applied by the pads to tissue, or alternatively, the amount of forced applied against the pads. 
       FIG. 14B  illustrates the vaginal dilation device  1400  after being partially dilated. Diameter gauge  1418   a  indicates the expanded diameter of the device to a user. Force gauge  1418   b  can be monitored by the user, or alternatively, by a controller (not shown) to ensure proper, safe use of the device and to prevent trauma to the tissue. In  FIG. 14C , vaginal dilation device is shown in a fully expanded configuration, effectively dilating the vaginal tissue to the desired diameter (e.g., 10 cm). Diameter gauge  1418   a  indicates that the diameter of the device has reached the target diameter to a user. Force gauge  1418   b  can be monitored by the user, or alternatively, by a controller (not shown) to ensure proper, safe use of the device and to prevent trauma to the tissue.  FIG. 14D  is an alternate view of a vaginal dilation device in an expanded configuration. The device shows diameter and force gauges  1418   a  and  1418   b  on the top of the device for easy readout by the user. Pads  1402  are shown applying pressure to the vaginal tissue, but avoiding putting pressure on the sensitive tissue areas of the urethra, the perineum, and anus. 
       FIG. 15  is a chart illustrating two methods of dilating vaginal tissue in a case study. Referring to the chart, the diameter of vaginal tissue was increased from 1.1 cm to 7 cm over a period of 1 hour and 15 minutes. The amount of force applied to tissue was ramped up gradually to avoid tissue damage. For example, initially, a force of approximately 2.5 lbs. was applied by the device to tissue to dilate the tissue to 4 cm after approximately 500 seconds. After the initial dilation, the tissue was allowed to relax, and it can be seen that the force applied by the device to tissue decreased to almost 1 lb. after approximately 1000 seconds. Next, a force of approximately 3 lbs. was applied by the device to tissue to dilate the tissue to 4.5 cm, followed by a time period of no additional dilation which allowed the force applied to decrease to below 2 lbs. This process was repeated by applying approximately 4.5 lbs. of force to dilate the tissue to 5 cm, applying approximately 5.5 lbs. of force to dilate the tissue to 5.5 cm, applying approximately 4 lbs. of force to dilate the tissue to 6 cm, applying approximately 6 lbs. of force to dilate the tissue to 6.5 cm, and applying approximately 7 lbs. of force to dilate the tissue to 7 cm. 
     It should be understood that these values are merely explanatory, as every woman&#39;s body and tissue response to treatment may be different. In general, however, a method of dilating vaginal tissue can comprise inserting a vaginal dilation device into the vagina, measuring a force applied by the vaginal dilation device to the vagina, dilating the vagina with the vaginal dilation device, and pausing or stopping dilation of the vagina with the vaginal dilation device when the force applied by the vaginal dilation device to the vagina increases to a first force threshold. In some embodiments, the method further increases measuring a diameter of the vagina with the vaginal dilation device. Next, the method can include resuming dilation of the vagina when the force applied by the vaginal dilation device to the vagina decreases to a second force threshold. For example, a user or controller may determine that the tissue has relaxed enough that it is time to begin dilating the vaginal tissue to a larger diameter. In some embodiments, dilation is resumed until the force applied by the vaginal dilation device increases to the first force threshold, or alternatively, until the force applied increases to a third force threshold larger than the first force threshold. In some embodiments, the first, second, and third force thresholds range from approximately less than 8 lbs. of force. 
     The embodiment of  FIG. 15  can utilize the visco-elastic properties of the patient&#39;s muscle and connective tissue to achieve maximum dilation. The tissue can be stretched to some predetermined maximum stress or force with the device, then the tissue can be allowed to relax to reduce the stress, followed by again increasing the diameter of the device to the maximum stress value. This cycle of tissue stressing, tissue stress relaxation, and then diameter increases to re-stress the tissue can be performed until the full tissue preparation diameter of approximately 10 cm is achieved. 
       FIG. 16  is a chart illustrating another method of dilating vaginal tissue during labor at a constant force.  FIG. 16  illustrates the results of a constant force dilation from a case study. Vaginal tissue can be dilated at a constant force with any of the vaginal dilation devices described herein, but particularly with the vaginal dilation devices described in  FIGS. 3 and 4 . Referring to the constant force dilation chart of  FIG. 16 , the vaginal diameter was increased from a baseline diameter of 1.0 cm up to 5.5 cm over approximately 1 hour. The force was held to lower values by incrementally increasing the diameter in smaller steps more frequently. As in the incremental dilation test (described above in  FIG. 15 ), there is a rapid decrease in force when first dilating to a new diameter, and by increasing the diameter more frequently, the tissue is allowed persistent stress relaxation. 
       FIG. 17  is a chart illustrating the various phases of labor and the relative dilation diameters of the patient&#39;s cervix and vagina. During the latent or first phase of labor, the cervix dilates up to approximately 3-4 cm over a span of about 8 hours. Over the final 6 hours or so of labor, the cervix dilates to approximately 10 cm. The natural stretch of perineal tissues is also shown in  FIG. 17 . It can be seen that the natural tissue response is for the perineal tissues to be dilated naturally at approximately 2 cm, until the final moment of labor when the perineal tissues stretch to 10 cm, leading to tearing and tissue damage. In one embodiment, the perineal tissues can be gradually dilated and expanded with a vaginal dilation device. For example, the perineal tissues can be dilated with the vaginal dilation device to approximately 7-10 cm during the first phase of labor. During the second phase of labor, the vaginal dilation device can be removed from the patient, allowing the birth to occur while the perineal tissues are stretch and relaxed. 
     The vaginal dilation devices described herein can be used during the first stage of labor, in the hospital, under the supervision of trained physician obstetricians and nurses. The device can be designed as a single use, disposable dilator configured to penetrate the first third of the vagina, and configured to gradually expand the vagina and the perineal tissues from a resting diameter of 2-3 cm to a fully expanded diameter in preparation of the delivering an infant, roughly 10 cm. Expansion can be controlled either manually or via an automatic actuation system, and the device can be removed quickly if needed 
     The device could be inserted any time during the first stage of labor, and can be configured to dilate in small 5-15 minute increments. In between dilations, the patient can remove the device and ambulate if needed. The progression of the cervix could be used as a guideline of the progression of labor. In order to reduce or eliminate any discomfort, the device can be used under epidural analgesia or local anesthesia on the vagina. In some embodiments, the device can dilate the tissue for approximately 1-3 hours to successfully reduce the internal stresses in the tissue and prepare the tissue for the second phase of labor. The device can then be removed prior to the second phase of labor begins, so as to allow delivery to occur unobstructed. 
       FIG. 18  is a chart illustrating an additional method of dilating vaginal tissue during labor. In  FIG. 18 , another embodiment of dilating vaginal tissue is illustrated. In this embodiment, the vaginal dilation device is configured to dilate the tissue at a constant rate. As the device dilates the tissue, the force applied by the device to the tissue will increase. This method can be used in situations where it is necessary to dilate the tissue quickly. A typical female has a resting vaginal diameter of approximately 2-3 cm. In one embodiment, it is desired to dilate the vagina to approximately 9-10 cm over the course of two hours, or approximately 3.5 cm per hour. Thus, in this embodiment, a constant rate dilation method could include dilating the device at a constant rate to achieve approximately 3-3.5 cm of dilation per hour. This could be achieved in a number of ways, such as dilating approximately 0.5 cm every 10 minutes, 1 cm every 20 minutes, etc. Any of the devices described herein can be used to dilate at a constant rate. For example, referring to the devices of  FIGS. 1-2 , the expansion mechanism or knob can be rotated at set intervals or at a constant rate to achieve a constant rate of dilation. The diameter gauge can be monitored in combination with rotation of the expansion mechanism to achieve a constant dilation. Similarly, the automated system of  FIG. 4  could be programmed to expand the device at any desired rate for any period of time. 
       FIGS. 19A-19B  illustrate another embodiment of a vaginal dilation device  1900 . The device can include pads  1902 , handle  1906 , arms (not shown), expansion mechanism  1908  central rod  1924 , diameter gauge  1918 , and any of the features described above and shown in the Figures herein. In the embodiment of  FIGS. 19A-19B , expansion mechanism  1908  comprises a trigger assembly configured to expand the device by a preset dilation increment. 
       FIG. 19B  illustrates a cutaway view of device  1900 . In  FIG. 19B , central rod  1924  can comprise a hexagonal or non-circular shape, and plates  1966  can be configured to engage the central rod to prevent the rod from travelling axially. When the trigger assembly is actuated, it causes plates  1966  to become parallel, allowing the central rod to move axially. As the trigger assembly is actuated, the central rod moves proximally, causing arms (not shown) and pads (not shown) to expand outwardly from the device, as described above in the other embodiments of the vaginal dilation device. 
     In some embodiments, a single “click” or actuation of the trigger assembly can be configured to dilate the device by a preset set dilation increment. For example, the device can be configured to expand a precise amount with each actuation of the trigger assembly. This design makes device  1900  particularly suitable for use in a constant rate dilation scheme. In one embodiment, for example, the trigger assembly can be configured to expand the device by a preset dilation increment (e.g., approximately 0.5 cm) with every “click” or actuation of the trigger. The user can then actuate the trigger assembly after a pre-determined period of time (e.g., every 10 minutes) to dilate the device at a constant rate. In other embodiments, device  1900  includes force sensors, as described above, and the user can dilate the device based on the sensed force of the device. It should be understood that in other embodiments, the preset dilation increment can be any amount (e.g., 0-1 cm per actuation, 0-2 cm per actuation, 0-3 cm per actuation, 0-4 cm per actuation, etc) and the predetermined period of time can be any period of time (e.g., anywhere from 0-2 hours or even longer). 
     All embodiments of the vaginal dilator devices described herein can be used in other applications beyond dilating vaginal tissue for childbirth. For example, in one embodiment, the vaginal dilator devices described herein can be used for the treatment of vaginismus. In contrast to using the vaginal dilation devices described herein to prepare a woman for childbirth, in which a target tissue diameter is somewhere in the range of 8-10 cm, when using a vaginal dilator to treat vaginismus it may be desirable to only dilate the vaginal muscles from 1-4 cm. Thus, many features described herein, which enable the vaginal dilation device to expand to greater than 10 cm, are unnecessary in a vaginismus application. Instead of starting at a base diameter of 1 cm and expanding to 10 cm or more, a vaginismus dilation device according to one embodiment may expand from 1 cm to 4 cm to treat vaginismus. A method of treating vaginismus can comprise, for example, expanding a vaginal dilation device described herein into a vagina of a patient, and expanding the device to up to 4 cm. A vaginal dilation device can be expanded in a vagina at a constant rate to treat vaginismus, or alternatively, the vaginal dilation device can be expanded in the vagina with a constant force. The user of the device can monitor the force being applied by the device to the vagina, as well as the diameter of the device within the tissue. Additionally, any of the devices described herein can be used as vaginal exercise devices, or additionally, as cervical dilator devices. 
       FIG. 33  illustrates one embodiment of a vaginal dilation device  3300  optimized to treat vaginismus. Since the device need only expand to approximately 4 cm, the scissor-like expansion mechanisms described above can be replaced with a simple cone structure  3302 . The cone structure can be coupled to a central rod  3304 . Manual rotation of knob  3306  can pull central rod and cone structure proximally Pads  3308  can include an internal cam surface  3310  configured to engage the cone structure. As the cone structure travels proximally, the internal cam surface  3310  of pads  3308  pushes the pads outwards, expanding tissue. It should be understood that any of the constant force (e.g., spring) or automated (e.g. motor) embodiments described above can be applied to the device of  FIG. 33  in place of the manual knob. 
     Another embodiment of an expandable vaginal dilation device is shown in  FIG. 34 . In this embodiment, the device utilizes a living hinge structure  3402  configured to expand in diameter when compressed axially. The axial compression of the device can be similar to any of the embodiments described above, in which a central rod is moved proximally within the device. The advantage of having small hinges as shown in  FIG. 34  can be to increase the initial angle of the hinge, thus requiring less initial force to open and expand the device. 
     In another embodiment, instead of preparing a woman for childbirth or treating a vaginismus condition, a vaginal dilation device can instead be used as a home workout device, similar to “Kegel Exercises.” In these embodiments, a user can use flex the vaginal muscles against any of the vaginal dilation devices described herein to build muscle strength to treat pelvic floor disorders. In these embodiments, vaginal dilation devices that provide an adjustable force and/or display the force applied by the device or the diameter of the device are preferred. 
     In  FIG. 35 , vaginal exercise device  3500  comprises a simple expansion mechanism comprising a pair of arms  3502  pivotable against a central rod  3504 . A spring or other constant force mechanism  3506  can apply a pre-load force against the arms, thereby causing pads  3508  to expand outwards at the pre-load force. A force dial  3510  can give the user feedback as to the actual force applied by the user against the device. With this device, the user can adjust the amount of force applied by the device to the tissue with knob  3512 , as well as see the amount of resistance applied by the user to the device. 
       FIG. 36  illustrates various embodiments of a cervical dilation device  3600 . The cervical dilation device can incorporate any of the features of the vaginal dilation devices, described above. Additionally, the pads of the device as well as extension apparatus  3602  can be configured to provide access to the anatomy of the cervix. The cervical dilation device can be used during labor to accurately determine the diameter of the cervix and/or help along the cervical dilation process. Any of the methods described above, relating to vaginal dilation, can be instead used to dilate a cervix of the patient. In some embodiments, the cervical dilation device is configured to dilate the cervix from approximately 1 cm to 10 cm. 
     As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed.