170 Normal Labor: The Four Stages, Fetal Heart Rate and Tracings

Hello and welcome to episode 170 of the Physician Assistant Exam Review Podcast. This week we’re going to be covering normal labor and assessing labor. My name is Brian Wallace. I’m the host and creator here at Physician Assistant Exam Review, and I am thrilled to be back. We’ve been away a little bit over the summer with just so much going on with the 33 Days cohort. A lot of exciting things going on behind the scenes, which have taken me away from recording the podcast, but now I’m super excited to be back here with you doing this. I want to be very clear up front.

We cover medical content on this podcast, today we’re going to be covering normal labor, right? But we do it from a different angle. We do it from the angle that we want your scores to improve. We don’t just want to cover the content. I don’t just want you to listen to this and let it wash over you. I want you to be participating, thinking, building out neural networks, concentrating on the ideas, answering the questions, doing the work that’s going to improve your scores. Everything’s set up that way for you as we go through this, and that’s the best way to get the most out of this.

Now, if you’re looking for another way to improve your scores, I’m going to be hosting a 100% free Master Class on Passing the PANCE. And I guarantee if you show up, we’re going to get you 5% to 10% higher scores on every exam, especially on the PANCE. You can go to physicianassistantexamreview.com/masterclass to find out more. That’s going to be happening September 17th, I’m sorry, 15th and 17th, 8 p.m. Eastern time. And so you can go find out more and you can register there. If you show up live, we’re going to have some fun things, especially on Tuesday the 15th.

So I’d recommend that you do that.

Okay, cool. So this week, like I said, we’re going to be covering labor and assessing the laboring patient. But first, we’re going to jump in with our priming questions. What single finding separates true labor from false labor? What single finding separates true labor from false labor? Active labor begins at what cervical dilation? Active labor begins at what cervical dilation?

Late decels should make you think of what underlying problem? Late decels should make you think of what underlying problem? Name the three findings that confirm rupture of membranes. Name the three findings that confirm rupture of membranes. A tracing with a moderate variability and early decelerations only is in what category? A tracing with moderate variability and early decels is only in what category?

All right. So what we’re going to do today, we’re going to start with normal labor, right? What is labor? What are the four stages? How does the baby’s head work its way through the pelvis? Step two is going to be assessing the laboring patient. So making some decisions.

We’re going to be rechecking where the baby is, what the cervix is doing, and whether the baby’s doing okay. That’s really the three things that you’re going to be following, right? That’s the most important step. So if you can hold on to that idea, so you have the four stages of labor, and then we’re going to assess labor by checking on where the baby is, what the cervix is doing, and if the baby’s doing okay. Hope that makes sense. So we’re going to jump in with normal labor and the stages and mechanisms here. Labor is regular uterine contractions producing progressive cervical effacement and dilation, ending in the delivery of the fetus and the placenta.

Taking a breath to let that sink in. Regular uterine contractions producing progressive cervical effacement and dilation, ending in the delivery of the fetus and placenta. So the two numbers drive every decision in labor. So it’s how open is the cervix, that dilation, and how low is the baby, the station. True labor versus false labor. In true labor, we have regular contractions getting closer together and stronger, right? True labor versus false labor.

So these get closer and closer and closer in time and stronger and stronger. That’s true labor, labor, part of true labor. You also get cervical changes on repeated exams. And in true labor, the pain starts in the back and tends to wrap around to the abdomen. I’m not saying this happens all the time. Every single patient, believe me, please understand that I’m never ever saying that. I’m just giving you the right up the middle version of this, not the outliers.

The other key to true labor is rest. Rest and hydration don’t stop it. It continues. The contractions keep coming. In false labor or Braxton Hicks contractions, the contractions are irregular. So they’re not spaced uniformly apart. There’s no cervical changes.

They tend to be only pain in the lower abdomen. And a lot of times, these can be relieved with rest, hydration, or walking around. But cervical change is really a mainstay here. A bloody show is the passage of blood or streaked mucus, the streaked mucus plug from the cervix. And for true labor versus false labor, you’re probably going to get a question stem that’s going to describe a woman with contractions and ask what you should do about it, right? And it’s going to describe the contractions to you. And you’re probably going to have to come up with the next step.

So this is your clinical decision-making type question.

All right, let’s jump into the four stages of labor. So first, we have stage one, or the first stage, which is onset of labor. This is the longest stage, right? So we have from zero to complete dilation. Latent phase is zero to six centimeters, slow and highly variable. So that beginning part is called latent phase, and it’s slow. Active phase is six to 10 centimeters.

Here, dilation is accelerating. So once you cross that six centimeter threshold, this picks up speed. So the first stage is broken into latent phase and active phase. This is what always confused me, right? When we start breaking out outlines into deeper and deeper outlines. I always struggled here because I didn’t quite get it. But it’s really not that complicated.

First stage is zero to 10 centimeters broken up into two separate sections.

Now, you can get an arrest of active labor here, right? So if we have greater than six centimeters and ruptured membranes and no cervical change for greater than four hours with adequate contractions or greater than six hours with inadequate contractions. So this is where labor sort of stops for a little bit. The second stage is completion of dilation. So we are at 10 centimeters dilated through delivery of the infant. This can take, you know, this varies from person to person. But in the books, nulliparous are up to three hours, multiparous are up to two hours.

If the patient has an epidural, we can add an hour to each of those, four hours, and then three hours. The third stage is delivery of the infant to delivery of the placenta. It’s usually delivered within 30 minutes. And after 30 minutes, we start to call it a retained placenta. Then we have a fourth stage, which is the first one to two hours postpartum. This is where we’re most concerned about uterine tone and hemorrhaging. So let me walk back through that because I get a little lost here.

So we have first stage, which is zero to 10 centimeters. We have second stage, which is complete dilation. So 10 centimeters to delivery of the infant. We have third stage, which is delivery of the infant to delivery of the placenta. We have the fourth stage, which is the one to two hours after the placenta comes out.

Okay, so that’s the main overview. I’m just going to run through it quick one more time. Latent phase is zero to six centimeters. This can take a while. This takes a long time. Active phase is six to 10 centimeters. That takes a little shorter.

From complete dilation to delivery of the baby is somewhere around two to three hours, optimistically maybe, three to four hours with an epidural. And then we want to deliver the placenta within about 30 minutes. Retained placenta is a very big concern for uterine tone. When I say uterine tone, I mean the uterus clamping down and stopping the bleeding. So I do a lot of C-sections with what I do at the hospital. And we’re always assessing uterine tone because this is the concern for hemorrhaging. If the uterus doesn’t clamp down, doesn’t tighten up after the baby’s been delivered, the mother’s at serious risk for hemorrhaging.

So we want to make sure that the tone is adequate. And retained placenta. So retained pieces of placenta will kind of stop that from happening.

All right, let’s talk about how the baby moves during this. How the fetal head negotiates the pelvis. I think, I’m not sure this is going to come across in exams, but I feel like you should have a handle on it. So you get engagement to descent, to flexion, to internal rotation, to extension, to external rotation, to expulsion. I’m going to put all the notes on the website. If you just go to physicianassistantexamreview.com/170, you can see this. I don’t expect you to memorize this as you’re sitting in your car, you’re out for a run.

But just so you have it somewhere, you can find it. Engagement is putting the head at station zero. Internal rotation brings the occiput anterior, which helps the mother push and relieves back pain.

Exam keys here. What are they going to ask you? What are we looking for? So labor equals contractions plus cervical changes. No change is Braxton Hicks contractions. Active phase starts at six centimeters. Second stage is two to three hours, maybe an extra hour if you have an epidural on board.

We’re looking at 30 minutes for the placenta to be delivered. And if the head is at the ischial spines, we call that engaged or station zero.

All right, we’re going to move on to assessing the laboring patient. The bedside eval that establishes where the fetus is, how the cervix is progressing, and whether the fetus is tolerating the labor progression. So that’s what we’re checking over and over and over again. So you have the stages of labor, but now it’s what do we do? What are we actively engaged in doing during those stages of labor? We’re checking on these things. So one of the things we’re checking is the fetal orientation.

So there are three things we check there. The fetal lie, the presentation, and the position. The lie is the fetal spine relative to the maternal spine. Most importantly, are they longitudinal, which would be normal? Are they transverse, which would be a problem? Or are they oblique, which is a problem? Presentation is the part entering the pelvis first.

So what part will we like to be entering the pelvis first? Hopefully you know this by now. So normally we want the head to be entering the pelvis first, right? We can either get a breech, which would be the feet first, or a shoulder first. Position refers to where the occiput is compared to the maternal pelvis. If the occiput is anterior, that’s favorable. And then you guys should know Leopold maneuvers.

These are abdominal palpations to figure out where the lie is, and the presentation, the position at bedside. I’m going to, I don’t do this myself, but I’m going to guess we’re using ultrasound at this point to determine those things. More than we’re doing Leopold maneuvers. Although you can kind of feel everything. You can kind of feel where the head is and whatnot. Cervical exam and station. Dilation is zero to 10 centimeters.

We talked about that. Effacement is zero to 100% thinning of the cervix. It’s a thick piece of tissue. I don’t know how else to describe this. And it gets thinner and thinner and thinner throughout the laboring process. The station is a presenting part relative to the ischial spines. So graded minus five to plus five.

Station zero is the head is at the spines and the head is engaged. Positive numbers are below the spine, right? So we’re moving a negative five means the baby’s all the way up, and a plus five means we’re out five centimeters below the ischial spines. We also want to evaluate the membrane status. So we’ve got the position of the baby. We’ve got the cervical exam. Now we’re going to check for membrane status.

Confirm the rupture of membranes with this triad. So you’re going to what you’re going to do is you’re going to look at three signs to confirm rupture of membranes. This is what you’re going to get asked on an exam. First, you’ll get pooling of fluid in the posterior fornix. The posterior fornix is a term that just used to bother me because I didn’t really know what it meant. This is just the area behind the cervix. If the patient is laying down all the way at the top of the vagina behind the cervix, and you can see this on the speculum.

If there’s fluid there, there’s a good chance the membranes have ruptured, right? Just sort of makes sense. Normal vaginal pH is 3.8 to 4.5. Amniotic fluid pH is 7.1 to 7.3. So you can use nitrazine paper. If it turns blue, that indicates that you have a ruptured membranes just based on the pH. You can also get ferning, which is another thing that took me a minute to grasp when I was in PA school.

This is just taking a sample of fluid. And dried amniotic fluid will crystallize into a leaf-like pattern, looking like a fern leaf on a slide. We’re going to monitor the fetus throughout this process. So we have fetal heart rate monitoring is going to be a main way we do this. Baseline is 110 to 160. I would absolutely know that. Under 110, bradycardia.

Over 160, tachycardia. Variability is very important. Fluctuation from the baseline. And the best indicator of fetal oxygenation. So we want a 6 to 25 beat per minute changes. That’s reassuring. If it’s less than 5 or absent, that’s less than reassuring.

That’s concerning. We want accelerations, which is greater than 15 beats per minute above baseline for 15 seconds. That really makes you feel better about what’s going on. So the fetus’s heart rate is going up and then coming back down. And going up a little and then coming back down. So that’s some of the ways that we monitor the fetus to make sure that things are going okay during pregnancy. I’m sorry, during labor.

Now, rather than having accelerations, which are encouraging, we can have decelerations, which are discouraging. Early decelerations mirror contractions. So they go along with the contractions. And this is usually head compression. This is usually the baby’s head being compressed by the contractions, which causes some decelerations. If you get variable decelerations, and they’re not timed with contractions, this is likely cord compression. And this is the most common one in labor.

And when we’re saying early, variable, or late, we’re talking about in relation to the contractions. So the most common one is this variable decel where the cord is being compressed. A late decel begins after the peak and recover after the contraction ends. This tends to be uteroplacental insufficiency, and this one is concerning.

Okay, so when we say decels, we’re relating them to the contraction, if they’re early in the contraction, it’s probably the head being compressed. If they’re not related to the contraction, it’s probably the cord being compressed. And if they’re late in the contraction, it’s probably uteroplacental insufficiency, and we get worried about this one. So the question stem is going to give you a tracing, or describe a tracing that’s going to show you where the decelerations are happening, where the accelerations are happening, and if we are reassured, or we need to do something about that. So categories for our tracings. Category one is baseline 110 to 160, moderate variability, no late or variable decels. Early decels may be present.

This is normal. We don’t do anything. 110 to 160, maybe some early decels, totally normal. Category two is we’re not sure. It’s indeterminate. We’re going to keep watching this closely. So anything that’s not category one or category three falls into category two.

Category three is absent variability with recurrent late or variable decels or bradycardia. This is abnormal. We need to do something. So this is just a way for you to see what needs to happen, how to act. Again, we talk about our clinical decision-making and how that works. We’re going to get into that during that Master Class next week. But it’s that clinical decision-making where you have to make the call.

It’s not just pure memorization. So if you have no variability, if you have variability, if you have variable decels or bradycardia, then you have to do something, right? That’s the next step. And that’s what those tracing categories are for. They’re meant to be an algorithm to help you move along. You can also measure the contraction adequacy. So there’s an external belt, if you haven’t seen it yet, that they put on the mothers, which show how often contractions happen, but not how hard they are.

And we talked earlier about that labor may slow down and stall out. And one of the questions is, well, can we measure how hard the contractions are, not just how frequent they are? And the answer is yes. We can measure how hard the contractions are, but we can also use an intrauterine pressure catheter. The catheter is placed inside the uterus and can measure the strength of the contractions directly. The downside here is that the membranes must be ruptured to get into the uterus. These are measured in MVUs.

I can’t pronounce the name, Montevideo. I don’t, I’m not familiar with it. So five contractions peaking at 50 millimeters of mercury above baseline equals 250 MVUs. Again, I’m not, that’s, that’s going to be normal or adequate. I don’t think you’re going to have to get into that much detail, but I just want to pass it along to you so you have some understanding of what’s going on there more than I think it’s going to be a test question.

All right. So our exam keys for this section, station zero equals the head at the ischial spines and that it’s engaged. How do we determine ruptured membranes? We do that through pooling, nitrazine blue or ferning. Moderate variability is the best sign of fetal wellbeing. Early decels equal head compression. Variable decels equal cord compression.

Late decels equal uteroplacental insufficiency. Absent variability with recurrent late decels is category three. We need to do something. And greater than 200 MVUs equals adequate contractions. Again, I, I, I am, it’s not my area, but I don’t think that’s going to be on there.

Perfect. All right. That’s going to wrap up the medical section of this. That was enough for me. This is again, not an area I’m super familiar with. So I’m going through the notes. And piecing it back together again and trying to look for, like I always do, the pieces that I think are going to be on your exam.

So even though I don’t necessarily know the information, what I tend to do, or what I do, is I help you to find the information that’s going to be tested. I help you to find the information that’s going to be asked about. I’m going to help you find the information you can hold on to. So you, I want you to see and do the same things. When you’re first learning all of this, you don’t know any of it. It’s all just a bunch of words on a page and you have to figure out what’s important, what’s not important. How to hold on to it, what to do best.

That leads us right into our study tip for today, which is you don’t need more hours. When people are struggling, when they’re labeled at risk and the faculty says you need to do better, you need to do more. Most of the time, it’s not about the hours. It’s about what you’re doing. So just like I did in this section, I was unfamiliar with labor, right? I don’t work in labor. It’s been a long time since I studied it.

It’s not my thing. But I can go through the material. I can see the categories. I can understand how they’re laid out. I can appreciate why someone else laid them out this way to help me, understand, get a picture in my head, and then have an algorithm to walk through or a decision tree to use. And I get better and I get better and I get better. And then I look for what are test questions.

And then I look for how can I remember this more? And then I look for how can I explain this to someone else? How can I work with this? So when you sit down and you say, okay, I’m struggling in PA school like everyone. It’s not how do I spend more hours? It’s how do I get more out of the hours I spend? So this to me is what I call study skills.

Everybody rolls their eyes when I say, I’m going to talk about study skills, right? Because you’re in a master’s level program. Of course, you know how to study. On the other hand, my definition of study skills is getting more points out of every hour you’re sitting. So if we can do that, man, we can make a huge, huge difference, right? It’s getting more points out of every hour. It’s not adding more hours.

I hope that’s clear. And we’re going to cover that in the Master Class. If you go to physicianassistantexamreview.com/masterclass, we’re going to walk through all of that. On September 15th, and you’re going to love, love, love what we’re doing there if you’re struggling.

All right, let’s jump into the priming questions. What single finding separates true labor from false labor? What single finding separates true labor from false labor? This was cervical changes, right? Regular contractions without cervical changes is false labor. Active labor begins at what cervical dilation? So this was phase one, and it was six centimeters.

Late decels should make you think of what underlying problem? We’ve gone over this a few times. Uteroplacental insufficiency. Name three findings that confirm a rupture of membranes. Pooling in the posterior fornix, nitrazine paper, turning blue, and ferning on a dried slide. A tracing with moderate variability and early decelerations only is in what category? That’s category one.

Totally normal. Absolutely nothing to do.

Perfect. I hope you got a lot out of this. This was a ton of fun for me to get back behind the microphone. I haven’t been here in a little bit. Absolutely check out the Master Class. I think you’re going to get a ton out of it. Also, for those of you who are, if you’re struggling and looking for more significant help, we will be running the 33 Days to Pass the PANCE program beginning October 1st.

That’s when the next cohort starts. Registration for that’s going to open mid-September. You can find out more at physicianassistantexamreview.com/33 and get on the wait list there. We’re only opening 50 seats for self-paid seats because we have a bunch of schools who are having students come in and I want to sort of cap the total. So it’s going to be 50 self-paid seats. So you want to get on that wait list if that’s something that you’re interested in.

All right, fantastic. This was so much fun. I can’t wait to talk to you guys again next week. Until then, take care. Take care.