Cram The Pance - S1E54 Placenta Previa & Placenta Abruption

Episode Date: March 16, 2025

High Yield Placenta Previa & Placental Abruption (abruptio placentae) ReviewReview for your PANCE, PANRE, Eor's, Physician Assistant exams, Medical, USMLE, Nursing Exams.Merchandise Link: https://cram-the-pance.creator-spring.com/►Paypal Donation Link: https://bit.ly/3dxmTql (Thank you!)Included in review: Placental abruption Abruptio placentae Placenta previa Third trimester bleeding Vaginal bleeding during pregnancy Abdominal pain in pregnancy Pregnancy risk factors High-yield OB/GYN review Clinical manifestations Ultrasound diagnosis Maternal hemorrhage Retroplacental hematoma Emergency obstetrics Fetal distress OB/GYN board review Placental disorders Pregnancy emergencies Hypertension in pregnancy Smoking and pregnancy risks Medical mnemonics for examsBecome a supporter of this podcast: https://www.spreaker.com/podcast/cram-the-pance--5520744/support.

All right. So in today's podcast, we're going to be going to be going to be going to be a couple high-yield complications related to pregnancy. This is going to be the first of a few podcasts I plan on making on pregnancy-related complications. Thank you, everybody, for the support, the really nice comments, the five-star reviews on Apple Podcasts and Spotify. I truly do appreciate it. Thank you so much. Let's go ahead and get started. So let's start with placental abruption, aka abruptio-placente. What is this? Well, it's a partial or complete separation of the placenta at or after 20 weeks of gestation. So we have this. premature separation of the placenta from the uterus. We'll talk about why this happens in a moment, but first let's talk about timing. So why is timing so important? Why is it generally only considered a placental eruption if it occurs after 20 weeks? Well, if this happens prior to 20 weeks, in that case, it's usually considered to be part of a spontaneous abortion rather than an eruption, except for some rare cases. And then it also has to be prior to fetal expulsion, and this part is pretty obvious. After the fetus is delivered, the placenta naturally separates from the of the uterus, and so this is no longer an abnormal finding. So again, timing, it's after 20 weeks

and prior to delivery of the fetus. All right, so we have this placental abruption, this separation of the placenta. Why is this happening? Well, it's due to a rupture of maternal vessels in something called the decidua basalis. So this is the main area to focus on for patho. Thrombin also plays a role with the clinical consequences seen, contractions, tissue breakdown, etc. But rupture of the maternal vessels in the decidua basalis is what you need to know. So quick anatomy review. The placenta is where the nutrient and gas exchange occurs between the mother and the fetus. It has two sides, the baby side called the Corion, and the mother's side, the decidua basalis, which is attached to the uterine wall. The decidua basalis contains the maternal blood vessels, arteries and veins that supply oxygen-rich blood to the fetus.

In a placental abruption, the vessels in the decidua basalis, mom's side, become damaged or weakened, which causes them to rupture, which obviously leads to significant bleeding, causing a hematoma. And all of this just pushes the uterine wall and placenta apart. And the separation, it can be partial or complete, depending on the severity of the bleed. So basically to recap in a placental abruption vessels in the deciduous rupture, these ruptured vessels bleed and accumulate, which eventually causes the placenta to separate and peel away. So then the next question becomes, why did these vessels rupture in the first place? And that takes us to our risk factors. So think, what are some things that damage and weaken blood? blood vessels that disrupt vascular integrity. Let's start with an easy one and that is smoking.

So this is one of the few modifiable risk factors. It's also associated with a fourfold increased risk. And it's thought to be related to its vasoconstrictive effects, which cause placental hypopersion, necrosis, etc. Another one is cocaine. Again, vasoconstriction, et cetera. Up to 10% of pregnant women using cocaine in the third trimester will develop an abruption. Hypertension. This one's really important. Fivefold increased risk compared to normotensive patients. Obviously, anytime the blood pressure is increased, you can have arterial wall damage. And then the next one is trauma. So blunt trauma, a motor vehicle accident, fall, et cetera. Even though this isn't the most common risk factor, it's definitely popular on exam questions.

And I have this one in school. So in trauma, like a motor vehicle accident, for instance, you have this rapid acceleration deceleration of the uterus, where the uterine wall stretches with the sudden movement as the uterus is pretty flexible. But the placenta, it's not so stretchy so it stays in place. So you have this shearing force that just rips the two apart. And then we have our last risk factor, which is previous abruption. Like so many things in medicine, if you had it before, good chance you'll happen again. And in the case of a placental abruption, very good chance. So there are some other risk factors, but those are the five to focus on smoking, cocaine, hypertension, trauma, and previous abruption. All right, let's talk about something super high

yield next. And that is your clinical manifestations. So for clinical manifestations, there's really two things that you need to know, pain and bleeding. Neither one is 100% in real life, but in preparation for an exam, you need to assume you'll be given the most common clinical presentation, which is abrupt onset of vaginal bleeding and mild to moderate abdominal pain. So let's talk about that. Vaginal bleeding, this is usually going to be abrupt and onset, and this is a key component, but it's not very specific because there's obviously other causes of third trimester bleeding, like with placenta previa, which will go over next. And there is something called a concealed abruption where most of the blood is actually trapped behind the placenta. And in these cases,

even in a very severe abruption, there may be little to no vaginal bleeding. So that's clinical knowledge, but for an exam, always be thinking classic presentation, which is abrupt onset of vaginal bleeding, as this will be how the vast majority of patients present around 80% of individuals with a placental abruption. Next, abdominal pain. So pain this is associated with the uterine contractions, which are often high frequency and low amplitude. So the abdominal pain, it's important because on an exam, in some cases, the only thing to differentiate an abruption from placenta previa is the mention of some type of abdominal pain. So, classic presentation, mild to moderate abdominal pain is going to be typical. Back pain is also a possibility

when the placenta is on the posterior wall of the uterus. In some cases, the abdominal pain can be very severe. So abdominal pain, very important to remember. So clinical manifestations, nothing's 100% in medicine, but for the exam, associate placental abruption with painful, very severe. So, vaginal bleeding at or after 20 weeks gestation. Next is our physical exam. So really just one thing to focus on. And this is really important because it's another key to help you on your exam question. And that is the uterus.

It's going to be tender and rigid on exam. You also may hear it being described as hypertonic, which just means high muscle tone, which is from those frequent contractions. So really important to remember rigid, tender, or hypertonic uterus. Okay, diagnosis next. So in acute placental abruption, it's mainly, a clinical diagnosis, and you should suspect this in any pregnant patient that has abrupt onset of vaginal bleeding, abdominal pain, contractions, especially in the presence of uterine tenderness

and increased uterine tone, as we talked about before. There are some other things that help support the diagnosis, fetal heart rate abnormalities, disseminated intravascular coagulation, which can be associated with abruption. So remember again, this is mainly a clinical diagnosis, and you should suspect it in any pregnant patient with sudden onset vaginal bleeding, abdominal pain, contractions, tender and rigid uterus. With that being said, you should also know ultrasound can be helpful. And what you should know for your ultrasound finding is something that's known as a retro placental hematoma, so a clot behind the placenta. If this is present, this strongly supports the diagnosis. And on an exam question, if you see this mentioned,

slam dunk, it's a placental abruption. In real life, it can be absent in a good deal of patients. So it's great if it's present, but not so helpful when it's not. ultrasound is also helpful to rule out your differentials such as placenta preview which will go over next so again diagnosis mainly clinical but the ultrasound what you're looking for the classic finding is going to be a retro placental hematoma all right so treatment it depends on a lot of factors including hemodynamic stability of the mother the status of the fetus and i don't think the questions you'll get will be about treatment but just so you have an idea part of the treatment is focused on hemodynamic support for the mother so things like blood transfusion iv fluids etc Of course, continuous fetal heart rate monitoring. And then depending on a number of factors, often emergent delivery is indicated, whether by vaginal or cesarean birth. Okay, so quick recap placental abruption, placenta is peeling away from the uterus prematurely. This is at or after 20 weeks of gestation and prior to birth.

Those maternal vessels, whether diseased from hypertension, smoking or damaged from car accident fall, have ruptured and are filling that separated space with blood. Most often we'll see bleeding on physical exam. in some cases the bleeding can be hidden. One thing I want you to remember is this patient will likely be in pain, very likely, contractions, etc. The uterus is going to be tender and rigid. Diagnosis is made clinically. Ultrasound if it shows a retroplacental hematoma slam dunk, but it doesn't always. For things you need to remember that always come up in the description on an exam question, that's pain, bleeding, the rigid uterus and contractions. This is how I remembered it, and hopefully it will help you too. Instead of placental abruption, I used to remember. it as placental crab ruption. Think of a crab with its little claws literally snipping the placenta away from the uterine wall. And crab and placental crab eruption stands for four super important things

you need to remember that will be on an exam question. So C in crab is for contractions. R is for rigid as in a rigid or hypotonic uterus. A is for abdominal pain, which is so important. And then B is for bleeding. So again, placental crab ruption, crab, crab, contractions, rigorous, rich, abdominal pain bleeding. All right, let's talk about the next condition, which will be very similar in many ways to placental abruption, and that is going to be placenta previa. And this is the presence of placental tissue that extends over or near the internal cervical os. So really straightforward in a normal pregnancy, the placenta is usually right around the top of the uterus. In placenta previa, the placenta is at the bottom of the uterus,

sometimes covering the entire cervical oz. This can cause a number of problems which will go over, But again, placenta preview, the placenta is in the wrong spot, plugging up the internal cervical oz and varying degrees. Now, why this happens? We're not really sure, which is good news from an exam standpoint, as one less thing to remember. But one hypothesis is that the upper uterine cavity where the placenta normally in plants is not well vascularized, whether this is due to previous surgery, multi-parity, or other issues. So I do have a quick mnemonic.

Placenta abruption, which we just went over, the placenta was moving away from the uterus. remember it's kind of being ripped apart. And placenta previa, the placenta is plugging up the uterus. So placenta abruption, placenta away, placenta previa, placenta plug essentially. So, placenta abruption has an A. So remember, the placenta is moving away from the uterus. Placenta previa has a P. So remember, the placenta is plugging up the uterus.

It's just another way to help you remember the differences between the two. All right, so with placenta previa, what are some risk factors you should know? There's three main ones to focus on, starting with a preceptive. previous placenta previa. Again, like so many things in medicine, if you had it before, higher risk of having it again. Previous cesarean birth, and then finally multiple gestation, so carrying more than one baby at a time, twins, etc. Once study found placenta previa was 40% higher among twin births than among singleton births. There's other risk factors increasing maternal age, smoking, cocaine use, mal fetus, but focus on the three we went over above,

if you're even going to bother memorizing risk factors at all. Because to be honest, they're not the highest you'll think to know. With that being said, though, let's talk about something that is very high yield, and that's the clinical manifestations. So let's start with the fact that this may be an asymptomatic finding on routine ultrasound at approximately 18 to 20 weeks of gestation. So the majority of placenta previews will be an asymptomatic finding on mid-trimester ultrasound examination, and luckily about 90% identified on ultrasound at 18 to 20 weeks will resolve before delivery. So many women may be asymptomatic, But this isn't what you should remember for the exam.

On the exam, they're not going to give you an asymptomatic patient. What they're going to give you is a patient with painless vaginal bleeding. Painless, I'll repeat it again, painless vaginal bleeding in the second half of pregnancy. The most common symptom of placenta previa is painless vaginal bleeding, which occurs in up to 90% of cases. Compare this to placental abruption, which again, remember, more often than not, had painful bleeding. So placenta previa, painless bleeding. Now, in real life, 10 to 20% of patients with placenta previa may have some pain from uterine contractions, et cetera, but we're preparing for an exam. And for an exam, remember the most common,

which is painless vaginal bleeding. So how do you remember that? Well, instead of placenta previa, remember it as placenta stevia. Placenta previa is now placenta stevia. Stevia, as we know, is that sugar-free or a sugarless sweetener. And placenta previa is the pain-free or painless vaginal bleeding. It works for me. I know it's a little weird, but hopefully it helps you too. Placenta stevia, sugar-free sweetener, pain-free vaginal bleeding. Okay, diagnosis. Let's first talk about what you do not want to do, and this will often be tested on so you don't want to perform a digital vaginal exam. Anytime there is any vaginal bleeding in the second or third trimester, a digital examination is absolutely contraindicated until you perform ultrasound

and rule out a placenta previa. If you perform a digital vaginal exam on a patient with placenta previa. Remember, the placenta, it's in the wrong spot, positioned low in the uterus covering or near the cervix, and a digital exam can reach this area and dislodge the placental's attachment site, causing severe bleeding. So remember that, because it definitely could be a question. Okay, so now that we know what we should not do, what should we do to help make the diagnosis? Well, that's using ultrasound. So this is how you diagnose placenta previa. Ultrasound is what you need to know. So you'll usually start with transabdominal ultrasound, a screening test and then the gold standard is with transvaginal ultrasound which provides better detail

and better defines the placental position now we just said never do a digital vaginal exam on a patient with a suspected placenta previa why the heck can we do a transvaginal ultrasound well with a transvaginal ultrasound you're able to visualize the anatomy so you're not going in blind and the optimal position of the vaginal probe is actually far enough away from the cervix to make this a safe test so when you do the ultrasound, what are you looking for to confirm the diagnosis? So that's going to be placental tissue visualized over the internal cervical oz. So again, diagnosis do not perform a digital vaginal exam. Do perform an ultrasound. What about treatment next? Just like with placental abruption, I don't think many or any questions will be asked about management, but just so you

have a general idea, in asymptomatic patients where placenta previa is seen on routine ultrasound at 18 to 22 weeks, close monitoring is an option. If you have a mother with an actively bleeding placenta previa, this is a potential obstetric emergency. So monitoring maternal hemodynamic status, blood transfusions, monitoring fetal heart rate. Once the bleeding has resolved, then some patients' outpatient management is reasonable. You want to recommend to avoid excessive physical activity, avoid sexual intercourse. Some women will receive antenatal corticosteroid therapy. And then when delivery is recommended, and some patient's vaginal delivery can be an option, but quite often a cesarean birth is recommended.

Okay. so placenta previa this is the abnormal presence of placental tissue that extends over or near the internal cervical oz while this may be an asymptomatic finding on routine exam the classic symptom of placenta previa that you will not forget is painless vaginal bleeding up to 90% of persistent cases will have painless painless painless vaginal bleeding remember placenta stevia sugar free pain free diagnosis do not perform a digital vaginal exam do perform an ultrasound treatment manage observe and deliver when appropriate. That's placenta previa. Now let's do a quick recap of what I feel are the highest yield things to know for both placental abruption and placenta previa. Okay, so placenta

abruption is a premature separation of the placenta from the uterus. Placenta previa is abnormal placental tissue over or near the internal cervical oz. So placenta abruption, placenta moving away from the uterus. Placenta previa is plugging up the uterus. Remember placental abruption has an A, so placenta is moving a way from the uterus. So placenta is moving away from the uterus. from the uterus and placenta previa has a P. So the placenta is plugging up the uterus. Next presentation, placental abruption, painful bleeding, cramping along with rigid hypertonic uterus on physical exam. Remember your placental crab eruption. And then placenta previa, remember painless vaginal bleeding. Remember placenta stevia, sugar-free, pain-free.

Remember placenta previa, you do not perform a digital vaginal exam, as this can cause severe hemorrhage. And finally, with placental abruption, a retro placental hematoma is the classic. ultrasound finding. So those are the most important things to remember about these two conditions. Let's do some questions next. Question one. A 32-year-old G3P2 woman presents to the emergency department at 28 weeks gestation with painless vaginal bleeding that started an hour ago. She denies any contractions, abdominal pain or trauma. Her pregnancy has been uncomplicated until now. On examination, she is hemodynamicly stable and the fetal heart rate is 145 beats per minute. Which of the following should be avoided in the workup of this patient. A, transabdominal ultrasound, B, transvaginal

ultrasound, C, digital vaginal examination, or D, fetal heart rate monitoring. Again, which of the following should be avoided in the workup of this patient? A, transabdominal ultrasound, B, transvaginal ultrasound, C, digital vaginal examination, or D, fetal heart rate monitoring. All right, so I'm sure you know the answer to that one, and that's going to be C, digital vaginal examination. All right, so we have a pregnant patient with vaginal bleeding after 20 weeks gestation, G3P2, meaning three pregnancies and two births at term. The vignette clearly states there is no pain or contractions, so while we can't definitively say that this is a placenta preview without imaging,

it should definitely be high on the list of differentials. Most important thing is to remember that any time a patient has vaginal bleeding late in pregnancy, you do not perform a digital vaginal examination until you rule out a placenta preview, as this can lead to severe hemorrhage. So the other answer is, ultrasound for answers A and B. This is first line imaging to assess placental position. That includes transvaginal ultrasound, which can be safely performed even with placenta Privia. And then finally, fetal heart rate monitoring, always appropriate with active vaginal

bleeding and a pregnant patient. So again, answer C, digital vaginal examination is the only choice that is absolutely contraindicated until Previa is ruled out. Question two, a 35-year-old G4P3 female, currently 36 weeks pregnant, presents to the emergency department after being involved involved in a motor vehicle accident. She's complaining of severe abdominal pain and vaginal bleeding. She admits to using cigarettes and cocaine during her pregnancy. Abdominal exam reveals a rigid uterus with palpable uterine contractions and blood is observed in the vaginal vault. If an ultrasound were performed, which of the following findings would be most consistent with the likely diagnosis?

A, placenta covering the internal oz and extending posteriorly. B, low-lying placenta, one centimeter from the internal oz. C, retro placental hematoma, D, normal placental position with no abnormalities. Again, which of the following would be most consistent with the likely diagnosis if ultrasound were obtained? A, placenta covering the internal oz and extending posteriorly. B, low-lying placenta 1 centimeter from the internal oz. C, retroplacental hematoma or D, normal placental position with no abnormalities.

Okay, that is going to be C, retroplacental hematoma. So first, what is the likely diagnosis in this patient? Well, first, does this patient have crab? She does. She has crab, which again, we know is contractions. She has a rigid uterus. She has abdominal pain and she has bleeding. So our suspicion for placental abruption should be high.

The vignette also mentions she was in a motor vehicle accident, which we know is a risk factor for placental abruption. And then finally, it mentions cocaine and cigarette use. Highly likely this patient has a placental abruption. And as we discussed earlier, while this may not be found in all patients, patients, a retroplacental hematoma or clot is a classic ultrasound finding and strongly supports the diagnosis. Question three.

For the patient referenced in the previous question, what underlying pathophysiological mechanism is most likely responsible for their condition? So in the patient we just mentioned, what underlying pathophysiological mechanism is most likely responsible for their condition. Okay. And remember, that is going to be rupture of maternal vessels in the decidua-based salas. So remember, in a placental abruption, vessels in the decidua basalis rupture, these ruptured vessels bleed and accumulate, which eventually causes the placenta to separate and peel away. Okay, so I hope that was helpful.

Thank you so much for listening. If it's helping you, please leave a review in the podcast comments. And if you really like it, a five-star review would absolutely be helpful. And thank you so much again.