Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
1998-05-05
2001-03-13
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
C600S426000
Reexamination Certificate
active
06200279
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for monitoring the progress of labor during childbirth.
Normal labor is generally divided into three stages: The first stage begins with the onset of labor and ends when dilatation of the cervix is complete; the second stage begins at that point and ends with the complete birth of the baby; and this is followed by the third stage which ends with the delivery of the placenta. During labor it is common to use either an external ultrasonic system for recording the baby's heart rate, and an external system for detecting the mother's uterine contractions, or an electronic system to sense the baby's heart pulses by an electrode attached to the baby's head and the mother's contractions by a pressure catheter applied to the mother inside the uterus.
However, a number of other physiological conditions of the mother and baby during labor must also be monitored in order to determine the progress of labor. These additional conditions include: (1) effacement (the thinning out of the cervix that occurs before and during the first stage of labor); (2) cervical dilatation (the increase in size of the cervical opening); (3) position of the cervix (the relation of the cervix to the vaginal axis, normally the fetal head); and (4) station (the level of a predetermined point of the fetal presenting part with reference to the mother's pelvis). The more common determination of station is the distance between the tip of the fetal head and the ischial spines which can be palpable by the physician; but a more accurate determination of station is the distance between the bi-parietal diameter (BPD) of the fetal head and the mother's pelvic inlet.
The foregoing conditions are generally determined by a physical examination, i.e., by the insertion of a finger through the mother's vagina. However, the accuracy of such a “finger” examination is very subjective and depends to a great extent on the experience, judgment, and even finger size, of the physician. Other drawbacks in such a physical examination are that it can be done only at spaced intervals, it generally produces discomfort to the mother, and it involves a number of risks including contamination, infection, dislodgment of a fetal monitor, injury to the baby, etc. Failure to interpret the precise stage of the labor progress from the physical examination can result in injury or even death of the baby or of the mother.
Many devices have been proposed in the past for automatically monitoring these conditions. As examples, U.S. Pat. No. 4,476,871 proposes an elongated tube having electrodes spaced along its length to monitor cervical dilatation during labor; U.S. Pat. Nos. 4,942,882 and 5,135,006 propose a fetal monitor probe attached to the fetal head to monitor heart beat, which probe is calibrated to monitor progress of descent; U.S. Pat. No. 5,222,485 proposes an elongated inflatable sac to monitor the position of the fetus and the configuration of the cervix; and U.S. Pat. No. 5,406,961 proposes a pessary to monitor the configuration of the cervix. However, for one reason or another, none of the previously proposed devices has come into any widespread uses and the historical “finger” examination continues to be the one in common use to this day.
OBJECTS AND BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and apparatus having advantages over the conventional “finger” examination technique for monitoring the progress of labor in a mother during childbirth.
According to one aspect of the present invention, there is provided a method of monitoring the progress of labor in a mother during childbirth, comprising: attaching a position sensor to a predetermined point on the mother's pelvic bones; monitoring the location of the position sensor in three-dimensional space relative to a reference; and monitoring the location of the fetal presenting part with respect to the predetermined point on the mother's pelvic bones to provide an indication of the progress of labor.
Three embodiments of the invention are described below for purposes of example. In one embodiment, the location of the fetal presenting part, and also of the opposite sides of the end of the mother's uterine cervix, are monitored by position sensors attached to these respective elements. In a second described embodiment, the latter are monitored by operating an ultrasonic transducer to image the mother's cervix and pelvic bones, and the fetal head, on a screen, and by using a position sensor on the ultrasonic transducer, and a marker for marking the screen, to locate the positions of these elements. A third embodiment is described utilizing both the four position sensors applied to the mother and the fetal presenting part, and a fifth position sensor applied to an ultrasonic transducer for imaging and locating the mother's cervix and pelvic bones and the fetal head
According to further features in the described first and third embodiments, the cervical dilatation of the mother's cervix is continuously indicated by continuously monitoring the positions of the position sensors applied to the opposite sides of the end of the cervix, and continuously displaying the spatial distance between them. The position of the fetal presenting part (e.g., fetal head) is also continuously indicated by continuously monitoring and displaying their respective locations
According to further features in the described preferred embodiments, the above conditions are computed and displayed in the form of units of distance (e.g., cm), and/or in the form of a graph, called a Partogram, showing the interrelation of the cervical dilatation and the descent of the fetal presenting part
According to a further aspect of the invention there is provided apparatus for monitoring the progress of labor in a mother during childbirth, comprising: a position sensor for attachment to a predetermined point on the mother's pelvic bones, and for producing an output signal identifying its location in space; means for sensing the location of the fetal presenting part with respect to the predetermined point on the mother's pelvic bones, and for producing an output signal identifying the location of the fetal presenting part; a computer connected to receive the output signals; and an output device controlled by the computer for outputting the position of the fetal presenting part with respect to the predetermined point of the mother's pelvic bones
The output device is preferably a display, but could be a plotter, recorder, or other device for displaying, recording, and/or processing the data outputted by the computer
As will be described more particularly below, such a method and apparatus permits the progress of labor to be monitored in a manner which is continuous rather than intermittent, which is less dependent for accuracy on the experience, judgment or finger size of the attendant in the conventional “finger examination”, which subjects the mother to less discomfort, and which involves less risk of contamination, infection, dislodgment of a fetal monitor, or injury to or death of the baby or mother due to a wrong assessment of the fetal position or of labor progress. Moreover, this technique enables more precise monitoring of the critical condition, namely the changes in the spatial distance of the BPD of the baby's head with respect to the pelvic inlet
Further features and advantages of the invention will be apparent from the description below.
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patent: 5935061 (1999-08-01), Acker et al.
patent: 31 03 367 (1982-08-01), None
patent: 2158767 (1973-06-01), None
K
Kenyon & Kenyon
Ultra-Guide Ltd.
Winakur Eric F.
LandOfFree
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