Goals: Identification of Needs
· To show you different view points regarding post dates and induction.
Reading and Listening Assignments:
· Read the OBGYN Morning Rounds case study on
Post dates induction
Keep in mind that this example is from the viewpoint of the medical model of care. So, you will see that it discusses the physician as the decision maker, and emphasizes risks associated with viewing pregnancy, labor, and birth as a “disease”. While under-emphasizing the risks of medical interventions.
Here in Labor and Delivery we have Candace Scoville. Candace Scoville is a 39 year old G-1 at 41 0/7 weeks gestational age, here for induction of labor because of post-date pregnancy.
She had an uncomplicated pregnancy, with her due date confirmed by first trimester ultrasound. This is important because many cases of “post datism” are actually cases of “wrong datism”.
As pregnancy advances past 36 weeks, placental function plateaus or even starts to diminish. Because the normal placenta has great reserve capactity, this loss of placental capabilities is usually not a problem, unless the patient goes way past their due date. Among some post date pregnancies, we can see evidence of reduced placental function, including fetal growth restriction, oligohydramnios and meconium staining.
One common approach to this issue is to not allow pregnancies to persist beyond a certain cut-off date, such as 41 weeks. After that, labor is induced. Of course, the main problem with this approach is that not all patients at 41 weeks will have a favorable cervix for induction. Consequently, some of these inductions take a very long time, with some increase in the cesarean section risk and the risk of infection.
To avoid those complications, some providers generally induce patients who cross the 41 week mark, but will hold off on the induction if the cervix is generally unfavorable.
Another approach is increased monitoring of the fetus with serial non-stress testing for fetal well-being, ultrasound evalauation to detect fetal growth abnormalities and oligohydramnios, or biophysical profiles. While this approach avoids the problem of inducing unfavorable cervices, none of our monitoring systems is perfect and watchful expectancy will not totally avoid the problem of placental dysfunction.
Some providers prefer induction of labor, even in the face of an unfavorable cervix, in order to decrease the risk of excessive fetal size, which can predispose toward shoulder dystocia and brachial plexus injury to the newborn. This preference is based on the knowledge that fetuses continue to grow larger throughout pregnancy and termination of the pregnancy at term will disallow further growth. There are some problems with this line of thinking.
While it’s true that fetuses continue to grow, they don’t grow much after 38 weeks, with their maximum rate of growth of 1⁄2 pound a week seen around 32 weeks of pregnancy. The incremental growth after the 40th week is quite small. So for induction of labor to be effective in reducing delivery weight of the baby, induction would have to be initiated around 36-37 weeks. By waiting until 41 weeks, we would have waited too long…the baby is already big. But initiating delivery at 36-37 weeks creates too much risk of prematurity to be justified for routine avoidance of fetal macrosomia, so it is not done.
In the case of this patient, she had an unfavorable cervix for induction (closed, 2 cm thick, firm, posterior, with the presenting part at -3 station). Her physician opted to bring her in at 40 1/7 weeks for cervical ripening with misoprostol for 12 hours, followed by pitocing for induction of labor. During those 12 hours, her cervix has changed from closed, 2 cm thick and firm, to soft, 2 cm dilated, 1 cm thick, and mid-position. We have started pitocin and she’s responding well, with contractions every 3
minutes, lasting about 60 seconds. The baby is tolerating this labor pattern normally.
We also could have used an EASI catheter, a balloon-tipped catheter that is threaded through the cervix and then inflated. The pressure of the catheter balloon, combined with slow irrigation of the lower uterine segment with normal saline, would be expected to dilate the cervix to several cm dilatation over the course of 6 hours. However, this forcible dilatation does not always cause the molecular ripening that we see with misoprostol, and in this case, we did not employ the technique.
Here in Labor and Delivery we have Candace Scoville. Candace Scoville is a 39 year old G-1 at 41 0/7 weeks gestational age, here for induction of labor because of post-date pregnancy.
She had an uncomplicated pregnancy, with her due date confirmed by first trimester ultrasound. This is important because many cases of “post datism” are actually cases of “wrong datism”.
As pregnancy advances past 36 weeks, placental function plateaus or even starts to diminish. Because the normal placenta has great reserve capactity, this loss of placental capabilities is usually not a problem, unless the patient goes way past their due date. Among some post date pregnancies, we can see evidence of reduced placental function, including fetal growth restriction, oligohydramnios and meconium staining.
One common approach to this issue is to not allow pregnancies to persist beyond a certain cut-off date, such as 41 weeks. After that, labor is induced. Of course, the main problem with this approach is that not all patients at 41 weeks will have a favorable cervix for induction. Consequently, some of these inductions take a very long time, with some increase in the cesarean section risk and the risk of infection.
To avoid those complications, some providers generally induce patients who cross the 41 week mark, but will hold off on the induction if the cervix is generally unfavorable.
Another approach is increased monitoring of the fetus with serial non-stress testing for fetal well-being, ultrasound evalauation to detect fetal growth abnormalities and oligohydramnios, or biophysical profiles. While this approach avoids the problem of inducing unfavorable cervices, none of our monitoring systems is perfect and watchful expectancy will not totally avoid the problem of placental dysfunction.
Some providers prefer induction of labor, even in the face of an unfavorable cervix, in order to decrease the risk of excessive fetal size, which can predispose toward shoulder dystocia and brachial plexus injury to the newborn. This preference is based on the knowledge that fetuses continue to grow larger throughout pregnancy and termination of the pregnancy at term will disallow further growth. There are some problems with this line of thinking.
While it’s true that fetuses continue to grow, they don’t grow much after 38 weeks, with their maximum rate of growth of 1⁄2 pound a week seen around 32 weeks of pregnancy. The incremental growth after the 40th week is quite small. So for induction of labor to be effective in reducing delivery weight of the baby, induction would have to be initiated around 36-37 weeks. By waiting until 41 weeks, we would have waited too long…the baby is already big. But initiating delivery at 36-37 weeks creates too much risk of prematurity to be justified for routine avoidance of fetal macrosomia, so it is not done.
In the case of this patient, she had an unfavorable cervix for induction (closed, 2 cm thick, firm, posterior, with the presenting part at -3 station). Her physician opted to bring her in at 40 1/7 weeks for cervical ripening with misoprostol for 12 hours, followed by pitocing for induction of labor. During those 12 hours, her cervix has changed from closed, 2 cm thick and firm, to soft, 2 cm dilated, 1 cm thick, and mid-position. We have started pitocin and she’s responding well, with contractions every 3
minutes, lasting about 60 seconds. The baby is tolerating this labor pattern normally.
We also could have used an EASI catheter, a balloon-tipped catheter that is threaded through the cervix and then inflated. The pressure of the catheter balloon, combined with slow irrigation of the lower uterine segment with normal saline, would be expected to dilate the cervix to several cm dilatation over the course of 6 hours. However, this forcible dilatation does not always cause the molecular ripening that we see with misoprostol, and in this case, we did not employ the technique.
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