Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
2000-06-08
2002-07-23
Shaver, Kevin (Department: 3736)
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
active
06423016
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of medical diagnostic devices and systems in the area of clinical obstetrics and more particularly to a system and method for the assessment of labour progress during childbirth. This invention is applicable in assisting decision making in clinical medicine and can be used to reduce the number of unnecessary caesarean deliveries.
BACKGROUND OF THE INVENTION
The labor of childbirth is the process by which uterine contractions cause the fetus and placenta to be expelled from the uterus and birth canal. Rhythmic contractions of the uterine muscle create a force that pushes the fetus against the opening of the uterus, commonly referred to as the cervix. The cervix is a tubular structure that is firm and closed during pregnancy, keeping the baby and membranes protected inside the uterus. At term, the cervix softens and in labor the continuing pressure of the fetus on the cervix causes it to shorten (efface) and to open (dilate) up to 10 centimeters. As the cervix completely effaces and dilates, the contractions and the mother push the baby through the birth canal. The level of descent of the baby through this passage is referred to as station. Contractions are the forces that promote cervical dilatation. Resistance of the cervix and the birth canal are the opposing forces to the contractions. In addition, the resistance of the cervix changes as it becomes more effaced and more dilated.
Commonly, the effacement, the dilatation, the frequency of the contractions and the station are measured clinically during labor and are used by the doctors to determine if the labor is progressing normally. Generally, if the doctor determines that the labor is progressing normally, the delivery is permitted to continue through the birth canal. However, if the doctor determines that the labor is not progressing normally, a cesarean section is effected to complete the delivery.
Cesarean deliveries are associated with maternal morbidity and an increase in the risk of complications during the current and the subsequent pregnancies. Cesarean deliveries are also more expensive than vaginal births.
Due to the very large number of possible combinations of values for the dilation, the effacement, the frequency of the contractions and the station, the evaluation of labor progress is a difficult task for doctors. Unlike most surgical procedures, there is no suitable postoperative confirmation of the preoperative diagnosis that can be used to validate the doctor's decision. By examining outcomes and cesarean rates in various centers, it is likely that a large number of cesarean deliveries may have been unnecessary.
Consequently, there is a need in the industry for providing an improved system and method for evaluating labor progress during childbirth such as to reduce the number of unnecessary cesarean deliveries.
SUMMARY OF THE INVENTION
In accordance with a broad aspect, the invention provides a method and apparatus for tracking the labor progress of a patient during childbirth. The apparatus includes an input for receiving a group of clinical measurements associated to a patient. The group of clinical measurements include clinical measurement collection during the last pelvic exam. The group of clinical measurements includes data elements indicative of a measurement of a previous dilatation of the cervix of the patient, a contraction count, a previous level of descent of the child, a previous effacement measurement of the cervix, an epidural status and a parity status. The parity status is indicative of either one of a first childbirth for the patient and a childbirth subsequent to a first childbirth. The apparatus also includes a processing unit operative for generating a reference measure indicative of a certain expected dilatation of the cervix allowing to assess the progress of childbirth by using the following formula:
x=AA+BB
*(1−
y
)+
CC*z+DD*w+EE*v+FF*u
where:
x is the certain expected dilatation of the cervix;
y is the epidural status;
z is the previous dilatation of the cervix measurement;
w is the previous effacement measurement of the cervix;
v is the previous level of descent of the child;
u is the contraction count;
and where AA, BB, CC, DD, EE and FF are a set of real numbers conditioned at least in part on the basis of the parity status. A signal indicative of a measurement of the certain expected dilatation of the cervix is released at an output.
In accordance with a specific example of implementation, the formula includes an error estimate data element indicative of a residual value. The processing unit is further operative to derive a range of expected dilatations of the cervix having a normal distribution on the basis of the error estimate.
Continuing the specific example of implementation, the group of clinical measurements includes a data element indicative of a current dilatation of the cervix measurement. The current dilatation of the cervix measurement to derive a ranking data element indicative of a percentile ranking of the current dilation of the cervix measurement with respect to the range of expected dilatations of the cervix on the basis of the certain expected dilatation of the cervix and the error estimate. A signal indicative of the ranking data element is then released at the output.
In accordance with a broad aspect, the invention provides the use of the signal indicative of the ranking data element released by the apparatus described here above for assisting in the determination of whether a cesarean delivery is required for the patient. More specifically, the ranking data element is indicative of the performance of the patient with respect to a reference population. For instance, a percentile of 90 means that the performance of this patient is at the level of, or is better than the lowest 90 out of 100 similar patients who delivered vaginally. In other words, this performance is much faster than average. A percentile ranking of 10 means that the performance of this patient is at the level of, or is better than the lowest 10 out of 100 similar patients who delivered vaginally. In other words, this performance is much slower than average. If a patient has a performance below a certain percentile, herein designated as the minimum normal percentile, the doctor may make the decision that a cesarean may be recommended. The minimum normal percentile may be determined by the hospital in which the delivery is taking place or by health standards or the likes. Typical minimum normal percentiles are in the range of 1.5 to 4 but may be higher or lower depending upon the hospital (or health institution policies) and depending on the condition of the patient.
An advantage of the present invention is that abnormal labor patterns can be more objectively diagnosed thereby potentially reducing the number of unnecessary cesarean deliveries.
In accordance with another broad aspect, the invention provides a computer readable medium comprising a program element suitable for execution by a computing apparatus for implementing the above-described apparatus.
In accordance with another broad aspect, the invention provides a system for tracking the labor progress of a patient during childbirth. The system includes an information gathering unit associated to a first entity identifier, the information gathering unit being suitable for receiving a group of clinical measurements associated to a patient. The system also includes a labor progress unit associated to a second entity identifier. The labor progress unit is operative for generating a reference measure indicative of a certain expected dilatation of the cervix allowing to assess the progress of childbirth. The system also includes a broker unit comprising a first communication port suitable for exchanging messages with the information gathering unit, each message including a destination entity identifier. The broker unit also comprises a second communication port suitable for exchanging messages with the labor progress unit, each message inclu
Bendavid Bruno
Boisclair Mario
Hamilton Emily
Kimanani Ebi
LMS Medical Systems Ltd.
Ratner & Prestia
Shaver Kevin
Szmal Brian
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