Abstract:
A measurement device for measuring the diameter and of a cervical os, including a first connector for connecting to a first portion of the cervical os, a second connector for connecting to a second portion of the cervical os, an expandable device positioned between the first connector and the second connector, and the expendable device being expandable to measure the movement of the cervical os.

Description:
PRIORITY 
       [0001]    The present invention claims priority under 35 USC section 119 based on a provisional application with a Ser. No. 60/763,289 filed on Jan. 30, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the field of medical devices and measurements. More particularly, the present invention relates to a method and apparatus for measuring the cervical os diameter of a patient during pregnancy and labor. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 6,039,701 discloses cervimeters and methods for measuring and detecting changes in a patient&#39;s cervix and cervical OS which includes a loop element which is securable to a patient&#39;s cervix where a peripheral dimension of the loop varies directly with changes in the cervical diameter. 
         [0004]    The uterine cervical canal serves as a conduit for the human fetus to exit the uterus, and the human fetus is subsequently passed through the vagina during the birthing process. It has long been known that the cervix normally undergoes a series of physical and biochemical changes during the latter portions of pregnancy which enhances the ease and safety of the birthing process for the mother and infant. For example, in the early stages of labor, the tissues of the cervical canal soften and become more pliable, the cervix shortens and the diameter of the cervical canal begins to increase at its proximal end of the internal os. As labor progresses, the cervical diameter growth propagates to the distal end of the cervical canal to the external os. In the final stages of labor, the external os dilates allowing for the unobstructed passage of the fetus. 
         [0005]    The monitoring of cervical diameter via serial vaginal exams is important in labor-management. This information regarding the progress of labor is used to diagnose such conditions as dysfunctional or arrested labor and cephalopelvic disproportion, determine the necessity for labor augmentation or cesarean section, indicate when the patient should begin to push the baby out and determine the appropriateness of timing of administrating various anesthetic/analegesic agents, among other things. The vaginal exam is performed by inserting the first and second fingers of a gloved hand into the vagina and up to the cervix. By spreading the two fingers across what is perceived to be the internal diameter of the cervix, an assessment is made based on experience, about the cervical dilation in centimeters. 
         [0006]    Acceptable, repeatable results can be achieved using this method. However, the variation between measurements can be significant due to the subjective nature of the measurements and may change with different examiners. Such measurements are discrete and must be performed serially to assess labor progress and ascertained whether intervention is required. This procedure carries with it a risk of infections; consequently it is desirable to keep the number of these procedures to a minimum. 
         [0007]    It is not surprising that there has been numerous historical attempts to provide a more accurate user-independent cervical diameter measuring device and to provide an automatic cervical diameter measuring device. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an objective of the invention to provide a measurement device to measure the dilation of the os with a simple and disposable device. 
         [0009]    It is an objective of the invention to provide a measurement device that is biocompatible. 
         [0010]    It is a further objective of the present invention to convert the output of the measurement device to a digital form and to transmit the output of the measurement device to a centralized monitoring station. 
         [0011]    It is a further objective of the present invention to activate an alarm if the output of the measurement device exceeds a predetermined limit. 
         [0012]    The measurement device of the present invention should be easy to insert. 
         [0013]    The measurement device of the present invention is both safe for the mother and child and comfortable for the mother while in use. 
         [0014]    The measurement device of the present invention includes cylinders which are designed to slip out of the mother before the dilation of the mother reaches full effacement, for example 10 cm. 
         [0015]    The measurement device of the present invention is comfortable because the measurement device has a small profile, resulting in no discomfort to the mother. 
         [0016]    The measurement device of the present invention is flexible and does not cause any trauma to the cervix of the mother or to the baby. 
         [0017]    The measurement device of the present invention should accurately determine the cervical diameter. 
         [0018]    The measurement device of the present invention should reduce the risk of infection. 
         [0019]    The measurement device of the present invention should result in the delivery process for women being less traumatic both physically and emotionally. 
         [0020]    The present invention includes a measurement device or mechanical sensor that can measure the cervical os diameter as it widens during pregnancy. As the os thins in the late stages of labor (effacement), the measuring device should fall out or out of the cervix, indicating imminent delivery. The measurement device includes a wire or tape that extends from the measurement device and extends from the body of the woman so that the user of the measuring device can detect changes in the length of the wire or tape. 
         [0021]    The measurement device includes a first connector and second connector to be attached to the diametrically opposite ends of the cervical os. Consequently, as the ends of the cervical os separate, the tape or wire is pulled by the separation of the cervical os. By the connection of the first connector and the second connector to the diametrically opposed ends of the cervical os, a direct measurement of the diameter of the cervical os can be obtained. The first and second connector can be connected with a spring to urge the first and second connectors apart. The tape or wire or can be connected to a distal end of the measurement device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which, like reference numerals identify like elements, and in which: 
           [0023]      FIG. 1  illustrates the measurement device positioned within the cervical os; 
           [0024]      FIG. 2  illustrates a cross-sectional view of the measurement device; 
           [0025]      FIG. 3  illustrates a cross-sectional view of another measurement device; 
           [0026]      FIG. 4  illustrates a perspective view of the measurement device; 
           [0027]      FIG. 5  illustrates another cross-sectional view of the measurement device. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]      FIG. 1  illustrates the measurement device  100  positioned within the cervical, and the measurement device  100  includes an expandable device  104  which includes a hollow housing to house a spring  112  or other such elastic device connected along a longitudinal axis of the expandable device  104 . The expandable device  104  is movable in the longitudinal direction and includes a first connector  102  positioned at one end of the expandable device  104  and a second connector  102  at the other end of the expandable device  104 . The first connector  104  and the second connector  104  are connected to diametrically opposing sides of the cervical os, and as a result as the cervical os expands or contracts, the expandable device  104  expands or contracts with the cervical os. The spring  112  traverses the interior of the expandable device  104  and is connected to the expandable device  104  at the distal end and at the proximal end of the expandable device  104 . The wire  108  enters the expandable device  104  at the proximal end of the expandable device  104  and is connected to the distal end of the expandable device  104  and is sufficiently flexible to allow the wire  108  to be bent so that it can exit the vagina without discomfort and sufficiently rigid to allow accurate measurement of the diameter of the cervical os. 
         [0029]      FIG. 2  illustrates that the expandable device  104  includes hollow cylinders  220 , where each successive cylinder  220  has a reduced diameter with respect to the preceding cylinder  220  so that the cylinder  220  can move within the interior of the adjacent cylinder  220 . As a consequence, the expandable device  104  expands in a telescoping manner by each cylinder  220  moving in the interior of the adjacent cylinder  220 . 
         [0030]    A cylinder  220  as illustrated in  FIG. 5  includes an outward projecting element  532  and an inward projecting element  530  to limit the amount of movement for the cylinders  220 . The cylinders  220  are designed to slip out before the dilation of the mother reaches full effacement which is approximately 10 cm. This aspect adds to the safety of the measurement device  100  because the measurement device then can be removed from the mother safely before it can interfere with the delivery of the baby. The measurement device  100  is expelled from the cervix of the mother if the cervix diameter dilates to approximately 10 cm or the head of the baby pushes the measurement device  100  out. Additionally, the measurement device is flexible so that no trauma results to the cervix or the baby. 
         [0031]      FIG. 6  illustrates an end view of the expandable device  104   
         [0032]    As the cervical os diameter expands, the spring  112  urges first connector  102  and the second connector  102  outwards, and the wire  108  which is connected to the distal end of the expandable device  104  moves towards this distal end of the expandable device  104  as the cervical os diameter expands. The wire  108  is covered by a sheath  106  which is connected to the expandable device  104  to protect the wire  108  and to avoid discomfort. The wire  108  and the sheath  106  exit the vagina and the wire  108  is connected to, in one embodiment, a scale device  110  to allow the user to measure the diameter of the cervical os. The scale device  110  includes indicia such as the number of inches or millimeters on a scale so that the user can conveniently monitor the diameter of the cervical os by the movement of the wire  108 . As the cervical os expands, the connectors  102  will move with the cervical os, and as the connectors  102  move, the expandable device  104  will expand along the diameter of the cervical os. The spring  112  will urge the connectors  102  outwards, and the wire  108  will move towards the distal end of the expandable device  104 . Consequently, the end of the wire  108  connected to the scale device  110  will move towards the vagina and the user can accurately determine the amount of movement of the cervical os diameter by examining the indicia of the scale device  110 . 
         [0033]      FIG. 3  illustrates another embodiment of the expandable device of the present invention which includes a weakened support connector  306  to support the connectors  102  in a spaced relationship. The weakened support connector  306  may separate after the connectors  102  are placed on the cervical os. 
         [0034]    The expandable device  104  should fall off or fall out of the cervix prior to delivery. The sheath  106  may be formed from transparent material and may include indicia so that the movement of the wire  108  can be observed by the user. The measurement device  100  may be disposable, 100% inert and biocompatible with no risk to baby or mother. The monitoring device  402  converts the length of travel of the wire  108  to a digital number which is read out, can transmit this digital number and provide audible or visual alarms. The expandable device  104  could be made from flexible plastic, and the connectors  102  could be formed from silicon. 
         [0035]      FIG. 4  shows a perspective view of the measuring device  400  including a monitoring device  402  to perform various functions associated with the measuring device  400 . For example, the monitoring device  402  can record changes in the movement of the wire  108  as a function of time so that the user can view these changes to determine if the delivery is proceeding satisfactorily. The monitoring device  400  could perform an integration to determine the rate of change of movement of the wire  108  and could activate an alarm if the movement of the wire  108  exceeds a predetermined threshold. The monitoring device  402  could communicate with other remote devices such as the personal computer a cell phone or other suitable device at a remote location in order to keep the user advised of the movement of the cervical os. The communication could be through a wired connection, a wireless connection, the Internet or any other suitable communication device. 
         [0036]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed.