So sometimes the question is, how well is the fetus going to tolerate that stress?
How well will they tolerate labor?
So there's another test that we can do called a contraction stress test to answer that question.
You see those words or hear those words, Contraction Stress Test,
as opposed to a non-stress test, okay?
This is what that test looks like.
So we're going to give oxytocin because usually patients are contracting on their own,
so we're going to give some oxytocin in order to stimulate contractions.
Now that can be done through an exogenous method
which means we're going to infuse oxytocin and that would be through an IV,
or we can use endogenous oxytocin.
Did you know that whenever the nipple is stimulated it releases oxytocin?
So this is really great postpartum.
So think about the postpartum patient breastfeeding.
Every time they breast feed it causes uterine contractions which slows and stops the bleeding,
so it's nature's way as sort of providing some prophylaxis against the hemorrhage. It's perfect.
But in order to elicit exogenous oxytocin, we had to gently stimulate the breast and the nipple.
So what we would do is get a warm cloth and gently roll the nipple back and forth
a few times until contraction start, usually about 2 minutes.
Once the contractions are in a regular pattern,
we would stop the nipple stimulation so two minutes off, take a break, two minutes,
take a break, until we get regular contractions.
We want, whether we use an endogenous or exogenous method
to have three contractions in 10 minutes because that's going to mimic what labor is like.
And then, what we don't want to see are any late decelerations or variable decelerations,
exactly, because those are going to be indications of stress.
Early decelerations are okay. Remember that, early decelerations, okay.
Here we go. Here's a contraction stress test and what do you notice?
First thing we want to know is that it's set up correctly.
Do we have three contractions in 10 minute? Well, yes, we do.
We can tell what three minutes is because we know what that axis means,
we can see how far apart they are, we can see all of that.
We definitely meet that criteria. Now let's look at the top graph.
Our first question is, is our baseline heart rate within normal limits?
Well, it looks like it's about 150, so we could say, yes to that question.
Are we seeing accelerations? Hmm, the answer to that question is no.
we don't see the heart rate going up, but what we actually see is the heart rate coming down,
so then our follow up question is going to be, is the decrease an early deceleration
because that's okay. In order to be in early,
we would have to see that the deceleration of the heart rate and the apex of the contraction
are happening at the same time.
Do they line up? No, actually they don't.
So what you see is that the deceleration is happening after the contraction.
It's a late deceleration and we know that late decelerations
are caused by uterine placental insufficiency,
so not good blood flow between the uterus and the placenta.
Because of nonstress test and a contraction stress test are so close together,
let's take a minute to make sure that we have those clear.
A nonstress test means that we're looking for the reaction of fetal movement
and the fetal heart rate. So if it's reactive, that's a good thing.
Remember me doing jumping jacks, I want my heart to react and compensate,
so a reactive NST is good, a non-reactive NST is bad
because it means that the oxygenation is not where it should be.
In a contraction stress test, we're looking at the response to stress, response to contractions.
So if the response to contractions is that we have either a variable or late deceleration
with more than 50% of the contractions that means that it's not a good response to stress.
There is a response and so that makes it positive, but that's actually bad, okay.
A positive contraction stress test is bad.
A negative contraction stress test is good, okay.
Go back through that a couple of times and make sure that you've got it.
So this is a negative contraction stress test, what do you notice that's different?
Well, you may or may not see accelerations, that's not really the point.
What I don't see are decelerations. I don't see lates, I don't see variable decelerations.
So even though this might not exactly be a reactive NST,
it's definitely a negative contraction stress test because I don't see variables
and I don't see lates with more than 50% of the contractions,
so this is actually a good thing.
This means that the stress of labor is not too much for this fetus and we can continue with our plan.