Emergency Obstetrical Ultrasound - SD

Introduction

Hi, my name is Dr. Peter Dule. I am the senior Vice Chair of radiology at the Brigham and Women's Hospital in Boston, a teaching hospital of Harvard Medical School.

My area of clinical expertise in radiology is ultrasound. We perform in our department a very high volume of ultrasound, especially, but not limited to obstetrical ultrasound.

I'll be spending the next half an hour speaking on emergency obstetrical ultrasound in the first trimester.

Reasons for Emergency Obstetrical Ultrasound

The major reason for doing an emergency obstetrical ultrasound in the first trimester is to evaluate a woman who has bleeding or pain or both.

When we do an emergency ultrasound in this setting, what we're looking for is to determine really whether the pregnancy falls into one of three categories.

It may either be a normal intrauterine pregnancy. It's not too unusual for women with normal pregnancies in the first trimester to have some bleeding or pain. The bleeding is sometimes called implantation bleeding, but really it's it can be a normal feature.

Second possibility in a woman with first trimester bleeding or pain is that she has an intrauterine pregnancy, but it's abnormal. It may be a failed pregnancy, also termed a spontaneous abortion, or one that is on the way to becoming a failed pregnancy or a failing pregnancy.

And the third possibility is ectopic pregnancy.

So, what you're gonna hear for the next half hour really is how we make the diagnosis diagnoses of an abnormal intrauterine pregnancy or an ectopic pregnancy when we do a first trimester ultrasound in a woman with symptoms of bleeding or pain.

Key Questions and Diagnostic Algorithm

The key questions when we're doing the ultrasound are, number one, does the ultrasound demonstrate an intrauterine gestational sac?

If it does, are the sac and its contents normal?

And are the adnexa of the structures outside the uterus in the pelvis normal?

And there's a fairly straightforward algorithm about how we use the answers to these three questions to arrive at a diagnosis.

So you can see that the first question is, is there an intrauterine gestational sac identified on ultrasound?

If the answer is yes, we then try and determine if the sac and its contents are normal. I'll get into how we determine that in a minute.

If the answer to that is yes, yes, there's an intrauterine gestational sac, and yes, the sac and its contents are normal, then our diagnosis is a normal intrauterine pregnancy, at least as far as we can tell on ultrasound. Everything is fine.

If the answer is yes, there is an intrauterine sac, but no, the sac and the contents are abnormal, then the diagnosis is an abnormal intrauterine pregnancy, either definite or possible pregnancy failure, and I'll be expanding a lot on this one in just a minute.

If the answer to is there a gestational sac in the uterus identified? If the answer to that is no, we don't see one, then the key question becomes, is there a complex or solid mass in the pelvis outside the ovary? And we'll see soon why. It's very important that the mass, that determining presence or absence of is outside the ovary.

If we do see such a mass, if we see an extraovarian complex or solid mass in a woman who is pregnant has a positive pregnancy test, but no intrauterine gestational sac, then our diagnosis is an ectopic pregnancy.

And finally, the final branch of the algorithm, if we see no intrauterine gestational sac and no abnormality in the adnexa, then we have the same differential diagnosis we started with. It's either a normal intrauterine pregnancy and abnormal intrauterine pregnancy or an ectopic pregnancy, and that's gonna require further follow up.

So the rest of the talk will be really devoted to expanding on the various branches of this algorithm.

Diagnosing Intrauterine Pregnancy

We diagnose an intrauterine pregnancy when we see one of three things.

If we see a fluid collection in the uterus that contains inside of it, an embryo with a heartbeat, as you can see here, that means that this is an intrauterine pregnancy.

If we see a fluid collection in the uterus with a little circle in it, representing the yolk sac, that also indicates that we're looking at and that there is an intrauterine pregnancy.

A third finding of an intrauterine pregnancy is a fluid collection inside the uterus with a double echogenic ring around it. This is called the double sac sign, and it's another ultrasound demonstration or another ultrasound proof that there is an intrauterine pregnancy.

Pseudo Gestational Sac

Now we do have to be careful though, there's something that we might term the pseudo gestational sac, which is when we see fluid in the uterus in a patient who's coming in to rule out ectopic pregnancy, there might be a tendency when you see some fluid like this with no embryo yolk sac or double echogenic ring to say, oh, that's just a pseudo gestational sac, and therefore the patient probably has an ectopic pregnancy.

This is a small fluid collection in a rule out ectopic patient. But if you look what happened to this particular woman, a little over a week later, we see a pregnancy, you can see the yolk sac, the heartbeat. And then about three weeks later, you can see a nice normal intrauterine pregnancy.

So this small fluid collection, don't think that you're seeing a pseudo gestational sac. Not all gestational sacs have the one of the three characteristic appearances that I showed you on the prior slide.

So overall, anytime you see an intrauterine fluid collection in an early pregnancy, even if it doesn't meet one of the criteria of having an embryo yolk sac or double echogenic ring around it, give it the benefit of the doubt. It may be an intrauterine pregnancy. There's a good chance it is an intrauterine pregnancy, even if it doesn't meet one of the three criteria.

Determining Normality of Gestational Sac and Contents

So let's now move down to the situation where we move in our algorithm. We've done the ultrasound, we've asked the question, is there an intrauterine gestational sac? And the answer is yes.

So then what we have to determine by ultrasound are whether the gestational sac and the contents of the sac, whether they're normal.

To answer that question, I've put up this table that lists many of the published norms for the gestational sac in early pregnancy, as for example, as a function of gestational age, the normal findings, if one is scanning transvaginally, include the following.

At five weeks, you expect to see a gestational sac with a double ring around it. At five and a half weeks, you expect to see a gestational sac with a yolk sac, and at six weeks, you expect to see a gestational sac with a heartbeat.

There are norms also as a function of the mean sac diameter. For example, when the mean sac diameter is eight millimeters, you expect to see a yolk sac. If it's 16 millimeters, you expect to see an embryo.

And there are norms also with respect to the pregnancy test, the beta HCG level, the crown rump length, for example, by the time the crown rump length is five millimeters, you should always see a heartbeat. You actually see it very often before it's five millimeters, but you should always see it by five millimeters.

The yolk sac should be less than six millimeters. There are norms for the heart rate and others.

So to know whether the sac or the gestational sac or it's contents are normal, really means knowing this table.

If a pregnancy meets all of the findings in this table, it the gestational sac is normal. If it is fails to meet one or more of these, we are concerned about an abnormality.

Diagnosing First Trimester Pregnancy Failure

So, in simple terms, when we're trying to diagnose first trimester pregnancy failure or spontaneous abortion, the basic rules are pretty simple.

A pregnancy with abnormal gestational sac or contents that in other words, a pregnancy gestational sac fails to meet one or more of the norms on the prior slides. Such a pregnancy is at elevated risk for pregnancy failure, but it doesn't prove that it's a failed pregnancy. It may prove to be normal.

Some of the abnormal findings based on the prior table are definitive for pregnancy failure, and others are worrisome, but not definitive for pregnancy failure.

And the key to accurate diagnosis of problems in the early first trimester are to know which abnormal findings are definitive for pregnancy failure and which are merely worrisome and need follow up.

Definite Pregnancy Failure

So how do we make the diagnosis? Well, the way that I do it is as follows.

There are two situations when I'll diagnose a definite failed pregnancy.

One is, if I see a crown rump length of five millimeters or greater, and there's no heartbeat, that pregnancy is not gonna make it. There's no need for a follow-up ultrasound.

A second situation in which I'll diagnose a definite failed pregnancy is if I know the gestational age to be at least six, six and a half weeks, and there's no heartbeat to be certain, I should know it to be at least six and a half weeks. If I see no heartbeat, then that's a definite failed pregnancy.

Now, note that the I have known to be in italics and in a different color. That's because we have to use definite criteria.

How do we know the pregnancy to be at least six and a half weeks? If a woman is six and a half weeks based on her last menstrual period, that is not certain information. The LMP is notoriously unreliable.

I would know it, for example, if a woman had a prior ultrasound, say an ultrasound a week ago, we saw yolk sac, so we knew it to be five and a half weeks. Then if it's a week later, I know it to be six and a half weeks today.

Another situation where I know the gestational age is when the woman got pregnant via in vitro fertilization.

So in these two situations, I would diagnose a definite failed pregnancy.

Worrisome Findings for Pregnancy Failure

Really, any of the other abnormal findings based on the table that I showed you a few slides ago are worrisome but not definitive for failed pregnancy.

So that, for example, if I see no fetal heartbeat and a crown rump length of one to four millimeters, I'm very worried, but not certain.

If I see a mean sac diameter of at least 16 millimeters and no embryo, I consider that worrisome, but not definitive.

If the beta HCG is a thousand or greater and there's no gestational sac, again, I'm worried, but it's not definitive for a failed pregnancy.

Other worrisome findings include a large subchorionic hematoma or a large yolk sac.

Findings Indicating Risk of Subsequent Failure

And then the last category in the diagnosis of early pregnancy failure is the situation where there is a heartbeat on the scan today. But I see something that makes me worried about subsequent pregnancy failure.

So, the embryo's alive today, there is a heartbeat. When would I be worried about subsequent failure?

Well, the situation would be that that would apply if there's a heartbeat today, but the heartbeat is slow. There's a slow heart rate in early pregnancy. And I'll get into very shortly into what how slow is slow is too slow for a heart rate if there's a heartbeat and a large subchorionic hematoma, heartbeat, and a large yolk sac, a heartbeat, and a low amniotic fluid volume.

All of those findings are worrisome for subsequent pregnancy failure.

Examples of Definite Pregnancy Failure

Here's some real life examples of the various categories and the various ways that we make diagnoses.

This is an example of definite pregnancy failure. You can see on the left hand image, the embryo, the crown rump length is measuring just over five millimeters on this transvaginal scan. And you can see on the video clip here, there's no heartbeat. This is definite pregnancy failure. No need for a follow-up ultrasound to confirm the diagnosis. The diagnosis is confirmed based on this scan alone.

Here's another example of a definite pregnancy failure. A woman came in early in pregnancy. She was having some bleeding pain. We did an ultrasound and we see a gestational sac with a yolk sac based on this ultrasound. We said that she's five and a half weeks along. We have no way of knowing whether the pregnancy is going to make it or not. In fact, we have no way of knowing whether there's a live embryo growing because it's too early to see the embryo.

She comes back a week later for a follow-up scan. At this point, you can see that there is an embryo. It's measuring three and a half millimeters, but there's no fetal heartbeat.

So in this situation, we know that this is a failed pregnancy with certainty, not because the embryo measures five millimeters. In fact, a dozen, it measures three and a half millimeters. But because we know that gestational age to be at least six and a half weeks based on a prior five and a half week ultrasound a week ago, and there's no heartbeat.

These are two different cases. A pair of images on the left, pair of images on the right. In both of these cases, there's an embryo measuring under five millimeters, and there's no heartbeat. This one measures just over three millimeters, no heartbeat. This one measures about two and a half millimeters. No heartbeat. Both of these are very worrisome findings.

In general, when you see any embryo that you can measure and there's no heartbeat visible, the pregnancy is not gonna make it. But it's occasionally they will, and that's why this is a worrisome but not definitive finding.

So in the case on the left on follow up ultrasound, there was demise. And no great surprise. The because of this worrisome finding the image on the case on the right. However, you can see one week later on follow up, there is a heartbeat. It was surprising to us, but it's because we will occasionally see a heartbeat on follow up. Occasionally these cases with a measurable embryo, with a with no heartbeat will go on to develop a heartbeat.

It's because of these that we diagnose probable pregnancy failure, not definite pregnancy failure. Whenever we see a crown rump length of one to four millimeters and no heartbeat.

Slow Heart Rate

One of the findings that indicates that the fetus or embryo is alive on today's scan, but is at elevated risk for subsequent failure. Pregnancy failure is a slow heart rate.

You can see with your eyes that this heartbeat looks kind of slow. When we do an M mode and we actually measure the heartbeat, we can see it's going at 80 beats per minute, which as you'll see in a minute, is a slow heartbeat.

When we see this, the pregnancy is almost certain to go on to fail because of the slow heartbeat. So we would follow this up in a week or two to determine whether to see how the pregnancy does.

Now how slow is too slow. Well, this slide is a little a little bit complicated, but what it represents is the findings of a study published several years ago by myself and Dr. Carol Benson.

We looked at the relationship of the embryonic heart rate to the first trimester survival rate.

If you look at the graph on the left, this is for a gestational age of less than six weeks in a day, or crown rump length of four millimeters or below, you can see that when the heart rate is less than 80, there's about a 0% first trimester survival rate.

As the heart rate increases from less than 80 to 80 to 89, 90 to 99, and greater than a hundred, the survival rate goes up and up and up until it hits a plateau above a hundred.

So we would consider a hundred or above to be normal, 90 and below to be slow, and anything in between 90 to 99 to be intermediate.

When the pregnancy is a little further along, 6.3 to seven weeks, or crown rump length of five to nine millimeters, the same kind of findings occur. As the heart rate goes up, the survival rate goes up. These numbers, though, are all 20 beats per minute higher.

So anything under a hundred has almost no chance of making it anything under a hundred. And 10 has a low chance of making it normal, as above one 20. And in between is the indeterminate range.

So to put these in a table up to 6.2 weeks, slow heart rate is anything under 90. A normal heart rate is anything over of a hundred or above, and in between is borderline 6.3 to seven weeks. These all go up by 20 beats per minute.

Large Subchorionic Hematoma

Another finding with that indicates that even though the embryo is alive today, even though we see a heartbeat today, there's an increased risk of subsequent pregnancy. Failure is a large subchorionic hematoma.

Here you can see on the lower image, there's a gestational sac, an embryo. We do a M mode, and you can see that the heart rate is 152 beats per minute. That's fine. What isn't fine is that there's a large complex fluid collection adjacent to the gestational sac, a large subchorionic hematoma.

And this means that even though the embryo's alive today, there's an elevated risk for pregnancy failure.

Note, though, that this was worrisome, but not definitive finding of problem in that. And that's why four weeks later, everything looks fine. We four weeks later, the fetus has grown. Heart rate is fine. It's measuring 165 beats per minute. And in fact, the subchorionic hematoma has resorbed and everything looks normal.

Some numbers for the risk of a that the risk associated with a first trimester subchorionic hematoma, the risk of subsequent pregnancy loss. These numbers come from a paper published by our group in radiology in 1997.

You can see here that the likelihood of pregnancy loss as a function of the size of the subchorionic hematoma. If there's no subchorionic hematoma or a small subchorionic hematoma, the risk of loss is the same. So a small subchorionic hematoma is clinically irrelevant.

A moderate size subchorionic hematoma, these are all classified subjectively. A moderate size subchorionic hematoma had a loss, a risk of loss of about 20% or about three times as high as the risk in a pregnancy with none.

A large subchorionic hematoma had a likelihood of loss of about 40% or a fivefold increased risk.

But note that even though 40% likelihood of loss is pretty high, there's still a 60% chance that the pregnancy is gonna make it like you saw in the prior slide, when there's a large subchorionic hematoma.

So, subchorionic hematomas, if they get moderate to large, are worrisome, but far from definitive that the pregnancy is not gonna make it.

This is a small, what we would categorize as a small subchorionic hematoma. I don't even report these. This I consider to be basically a normal ultrasound in the early first trimester.

Large Yolk Sac

Another pregnancy, it's alive. You can see the heartbeat, but notice the yolk sac sitting beside. It looks large. I don't routinely measure yolk sac, but if it looks large, I put the calipers on it. You can see it's measuring nine millimeters. Anything above six is normal. So this is worrisome.

So we follow up worrisome pregnancies, and you can see here that a month later, there was no heartbeat, and the embryo hadn't grown nearly as much as we expected. It was about nine and a half weeks size, suggesting that it had the heart continued beating for about two and a half weeks after this seven week pregnancy, but then stopped.

Ectopic Pregnancy

Well, let's move on to the second main diagnosis that we consider in women with first trimester bleeding or pain, namely ectopic pregnancy.

So again, when the woman comes in with first trimester symptoms, especially early first trimester symptoms, the main two things that we're looking for on an emergent basis are failed pregnancy or ectopic pregnancy.

Locations of Ectopic Pregnancy

The location of ectopic pregnancy is as follows, the most common location, representing about 95% of ectopic pregnancies, at least in pregnancies that are achieved naturally, not via in vitro fertilization. 95% of ectopics occur in the fallopian tube, in particular in the isthmic or ampullary portion of the tube. In other words, some part of the tube outside of the cornua of the uterus.

Uncommon ectopic pregnancy locations, which represent about 5% of ectopic pregnancies, but higher than that in pregnancies achieved via assisted reproductive techniques such as IVF include a heterotopic pregnancy, one in the uterus and one outside one ectopic.

Another uncommon pregnancy is ectopic pregnancy is in the interstitial portion of the tube. In other words, the portion of the tube that goes through the cornua of the uterus.

Cervical pregnancies, intraabdominal pregnancies, and cesarean section scar pregnancies are all uncommon locations. And these, again, as a group form about 5% of ectopics.

Diagnostic Table for Ectopic Pregnancy

The following table is something that we find very useful in diagnosing and helping us to diagnose a rule out ectopic pregnancies. And this table, again, comes from a paper published in radiology by our group at the Brigham and Women's Hospital in Boston.

What we looked at, we did a so-called meta-analysis of these studies in the literature looking at what the likelihood of ectopic pregnancy is in a patient with a positive pregnancy test, symptoms of bleeding or pain, and nothing in the uterus.

So what's in such a patient in this patient is what we call a rule out ectopic patient. There's a positive pregnancy test symptoms. If she has nothing in the uterus, what's the likelihood of an ectopic pregnancy as a function of the adnexal findings outside the ovary?

This table shows it. If in this rule out ectopic patient with nothing in the uterus, no intrauterine gestational sac, if we see in the adnexa a mass with an embryo or a yolk sac, the likelihood of ectopic is a hundred percent. We've diagnosed it. If we see a mass in the adnexa with an embryo or yolk sac, what if we see a adnexal lesion outside the ovary that's surrounded by a bright ring called a tubal ring?

That indicates based on our meta-analysis, about a 95% chance of ectopic pregnancy. But in fact, if you see any complex or solid mass in the adnexa outside the ovary, the chance of ectopic pregnancy, if the patient has a positive pregnancy test, nothing in the uterus and a complex adnexal mass outside the ovary, the chance is still over 90%.

If we see free fluid, a lot of it, in a rule out ectopic patient with nothing in the uterus, her chance of ectopic is high. We weren't able to quantify it in our meta-analysis with a number, but the chances high.

So anytime the adnexa are abnormal outside the ovary in a rule out ectopic patient, the chance of ectopic is either a hundred percent or is at least high, and the woman in general, we will be treated for ectopic pregnancy.

Now, the flip side is if you have a patient with a positive pregnancy test, symptoms of bleeding or pain, nothing in the no intrauterine gestational sac. If the ultrasound is normal or, and that's normal in the inside the uterus, normal in the adnexa outside the ovary, really doesn't matter if we see anything in the ovary.

Anything in the ovary inside in a patient with a positive pregnancy test is almost certain to represent a corpus luteum. A corpus luteum is a normal part of early pregnancy, and it can look like anything. It can look like a simple cyst, a complex cyst, a solid mass.

So really anything in the ovary in a patient with a positive pregnancy test should be ignored as a corpus luteum.

So any normal ultrasound with or without ovarian lesion in a ectopic patient with nothing in the uterus, that indicates about a 5% chance. So, a normal ultrasound in a ectopic patient doesn't absolutely rule out ectopic, but the likelihood of ectopic is pretty low. It's about 5% if the ultrasound is completely normal.

So if we put these numbers into a table, we get some pretty straightforward basic rules for ultrasound diagnosis.

If we have a rule out ectopic patient, one with positive pregnancy tests and symptoms, if the ultrasound finding is an adnexal mass with a heartbeat or yolk sac, we interpret it as definite ectopic.

If the ultrasound finding is an extraovarian mass without a heartbeat or yolk sac, a tubal ring, or any other one, we diagnose probable ectopic if there's a moderate to large amount of free fluid in the pelvis in this rule out ectopic patient, we would also say probable ectopic.

If the ultrasound is normal with or without an ovarian lesion, we would say possible, but unlikely ectopic or can't rule ectopic, this corresponds to about a 5% chance. That's why it's possible, but unlikely.

And finally, if we see an intrauterine pregnancy in this ectopic patient with positive pregnancy test and symptoms, if we see an intrauterine pregnancy, then an ectopic pregnancy is virtually excluded. But of course, we would still check the adnexa in this patient.

Now, in the one situation above where the if we have a normal ultrasound in a ectopic patient, the differential becomes is really what it started at before we did the ultrasound. Either an ectopic that we're not seeing or a failed intrauterine pregnancy or a normal early intrauterine pregnancy, at least if the beta HCG is less than a thousand.

Ultrasound Examples of Ectopic Pregnancy

So, let's go on to look at some ultrasound examples of these.

This is a definite ectopic pregnancy. Here is a coronal or transverse view of the pelvis. You can see the uterus here. It continued there, there was nothing in it, but we see what looks like a gestational sac in the left adnexa. And here on the real time video clip, you can see that it's definitely a gestational sac in the adnexa. So it's a definite ectopic pregnancy. There's a heartbeat. There's a live embryo outside the uterus.

Here's another definite ectopic pregnancy. Nothing in the uterus, in the adnexa. So you can see the ovary here. But more importantly, beside the ovary, there's a fluid collection that we know to be a gestational sac. It has a bright ring around it, but more importantly, it has a little circle of a yolk sac. This is an ectopic pregnancy with 100% certainty.

What about this woman? She also came in as a rule out ectopic positive pregnancy test symptoms. We looked inside the uterus. We saw no pregnancy. We look in the right adnexa in this case. There's the ovary. It has a few follicles beside the ovary. There's a fluid collection, bright ring around it. This is called a tubal ring. And when we see this, it indicates a over 90% chance of an ectopic pregnancy.

It's not quite a hundred because we're not seeing a yolk sac or embryo, but it's high enough. And this woman would be treated in most places, certainly in our hospital as a presumed ectopic pregnancy, because the chance is very, very high.

This is another woman who came in as a rule out ectopic. You can see here the ovary. There's a nondescript mass beside the ovary, not a tubal ring appearance. It just looks like a solid mass since this woman came in with a positive pregnancy test and there was nothing in her uterus. And we're seeing this mass. This indicates a and it's a nonovarian mass. This indicates an over 90% chance of ectopic pregnancy.

We're likely looking not at the ectopic itself, but the mass in this case is probably a hematoma from a bleeding ectopic pregnancy.

Dilemmas in Diagnosis: Intra- vs. Extra-Ovarian Masses

So far I've said that the rules are pretty straightforward, and they are, and in most cases, we can pretty straightforwardly put the ultrasound in rule out ectopic patients in one of the categories that I talked about.

So why isn't it always easy? Well, one of the reasons that it's not always easy is that we sometimes get into a dilemma when we see a mass in the adnexa that we're not sure whether it's in or outside the ovary.

We see a mass right up against the edge of the ovary, and it's unclear whether it's really in the ovary or outside the ovary.

Here are three examples. Here's the ovary, and here's a mass. Kind of looks like a tubal ring, but maybe it's just a corpus luteum. Maybe the outline of the ovary is here and it's just in, but bulging outward from the ovary. And if if so, if the ovary comes out to here, this is a nothing. It's a corpus luteum. The ovary ends here and it's outside. It means that there's a 95% chance, but we're not sure, not always so easy to tell.

Similarly, this fluid collection with a ring, is this bulging out from inside the ovary or is it beside the ovary? Makes a big difference, but not always so easy to tell.

And similarly, here, is this thing inside the ovary, if this is the contour of the ovary, or is it outside? If this is the contour of the ovary.

So that's one of the biggest dilemmas that we have, or one of the biggest difficulties that we have in applying the straightforward rules that I listed on the earlier slide on follow up.

This patient had an intrauterine pregnancy, so this was presumably a corpus luteum, and these two proved have ectopic on follow up.

So how do we tell the difference? Well, one of the important rules or ways to tell the difference utilizes the fact that ultrasound is a real time specialty. The person doing the ultrasound has the probe in his or her hands, and can do things with it and watch what we can do here.

Here is a woman who came in as a rule out ectopic patient. This is the edge of the uterus that was out here, but there was nothing in it. When we look at the left adnexa, we can see the ovary and a mass. Is this mass in the ovary? Does the ovary come out to here? In which case, this is a corpus luteum. So the ultrasound is basically normal, indicating a 5% chance of ectopic.

Or does the ovary end here? And this is an extraovarian mass indicating a 95% chance of ectopic pregnancy? Is it five or 95? Big difference. How do we tell?

Well, we have the probe in our hand. We can push and we can see if these move together or separately and watch what happens when we push. You can see these move somewhat separately. The mass is sliding along the edge of the ovary, not moving with it, so it's beside the ovary, and we say 95% chance of ectopic pregnancy.

So using this maneuver helps us, in many cases, distinguishing between a mass that's beside the ovary or a mass that's inside the ovary.

Role of Doppler

What about the role of doppler? I haven't talked about doppler. Well, doppler is really not helpful in almost all cases.

Doppler is certainly not helpful if we see an intrauterine pregnancy. That tells us already before we turn on any doppler, that there's almost certainly not an ectopic.

If we see an extraovarian mass, Doppler doesn't help. We already have the diagnosis of almost certain ectopic pregnancy. And doppler is not gonna change from an almost certain ectopic pregnancy, whether we see flow or no flow.

In fact, if there's an adnexal mass and we're not sure if it's intra or extraovarian doppler won't help because the Doppler findings in a corpus luteum are very similar to the Doppler findings in an ectopic pregnancy.

And finally, dopplers not helpful. If an ultrasound shows normal adnexa in this case, there's nothing to doppler.

Doppler can even be potentially misleading if the ultrasound shows an adnexal mass and there's little or no flow on the Doppler. What we're probably looking at if we see a an adnexal mass with little or no flow in the doppler is probably a hematoma in a patient with an ectopic pregnancy. And we expect to see little or no flow on doppler in a hematoma.

So if you believed the doppler, you would be misled by it. The fact that you're seeing an adnexal mass is already indicative of a likely ectopic pregnancy.

Doppler can be helpful in rare situations. The rare situation in which doppler can be helpful is when the ultrasound is equivocal for an adnexal mass.

So just some examples. Can doppler help in these women with symptoms, positive pregnancy tests, no intrauterine pregnancy. These are cases that we've seen in the last few slides when we see in this case, there's a gestational sac with a heartbeat. The likelihood of ectopic based on the gray scale ultrasound of a hundred percent Doppler will certainly not help.

What about this case? There's a tubal ring, well indicating a 95% chance of ectopic. Will Doppler help? No. What about this case? There's a normal adnexa here is cyst, follicle in the ovary, maybe a corpus luteum. There's nothing to Doppler in this case. It won't help. Doppler in this case could only potentially mislead us.

Here we see the ovary in a ectopic patient. There's probably a corpus luteum. There's a tubal ring beside it. If you this indicates a 95% chance of ectopic. Now, what if you happen to turn on the Doppler? And when you turn it on, you see there's some flow in places beside this, but no flow around it. So there's no surrounding color in this case.

Which do you believe the gray scale finding that would indicate a 95% chance, or the doppler that shows no surrounding color? Well, you better believe this one, the gray scale, because this patient has an ectopic pregnancy, it's probably somewhat of a chronic ectopic, and that's why there's no blood flow.

But more importantly, we're gonna believe the gray scale. And since we're gonna believe the gray scale, regardless of what the Doppler shows in this case, there's no point in doing the doppler.

So the diagnostic approach for ectopic pregnancy is to scan transvaginally and put the ultrasound into one of four categories that I showed above that I showed previously.

If the transvaginal scan is inadequate, for example, there's a fibroid in the lower uterine segment that doesn't allow you to see well through it, do a transabdominal scan.

And if the transvaginal ultrasound is equivocal for an adnexal mass, which doesn't come up too often, then you can do doppler.

Unusual Ectopic Pregnancies

And I'll end by talking about some unusual ectopic. Everything I've said so far about ectopic pregnancy relates to the usual 95% of ectopics in the tube.

There are unusual ectopics include abdominal pregnancies, cornual ectopics, cervical ectopics, heterotopic, and pregnancies implanted in cesarean section scars.

So an abdominal pregnancy can be surprisingly difficult to distinguish in some cases from an intrauterine pregnancy. As we'll see in this slide.

If you look at the slide on the left, this is about a 15 week pregnancy. There's the baby's head, the body, there was a heartbeat. Things looked normal. And at first sight, you could say this is a normal intrauterine pregnancy. There's the cervix, there's the body of the uterus with the pregnancy.

But on closer look, you can see that this is not the cervix, it's actually the entire uterus. There's the fundus of the uterus, and this is an abdominal pregnancy, pregnancy, lying free in the abdomen.

Cervical ectopic pregnancies can also pose a diagnostic problem, distinguishing a cervical ectopic pregnancy when implanted in the cervix from a spontaneous abortion in progress, a pregnancy that is sitting in the cervix when you are doing the scan, but it's really on the way of pass, just passing through on the way out, schematically, cervical ectopic.

We diagnose when there's a normal looking gestational sac in the cervix, especially one with a heartbeat. We would diagnose a spontaneous abortion in progress if we see a flattened sac with nothing much in it and nothing, not much of a decidual reaction or bright ring around it.

In words. The diagnostic criteria are that if the ultrasound finding in the cervix is a well-formed sac with a prominent ring around it, especially if we see a live embryo, we diagnose a cervical ectopic.

If there's a flattened irregular sac with a thin or absent echogenic rim, we diagnose a no live embryo. We would diagnose spontaneous abortion in progress.

Sometimes the finding is somewhere in between these. If it's equivocal and the patient is stable, we can wait a day or two in equivocal findings when the findings in the cervix are equivocal.

If it's unchanged a day or two later, we diagnose cervical ectopic if it's changed or absent. We diagnose a spontaneous abortion in progress here, side by side examples.

These images, these images on the left, you can see there's the fundus of the uterus. No pregnancy in the body of the uterus. Here in the cervix though is a gestational sac that looks normal and there's a heartbeat. In fact, it is a normal looking sac. What's abnormal about it is where it is. It's in the cervix. This cervical ectopic pregnancy here this patient on the right has a different looking gestational sac in the cervix. It's flattened irregular, no, not much of a bright rim around it.

On this realtime clip, you can see yolk sac, but no embryo. This is a spontaneous abortion in progress.

Cornual ectopic pregnancy. One that is situated in the cornua of the uterus. On the right is another form of ectopic. It can be also difficult to diagnose. It can be difficult to distinguish in some cases between an intrauterine pregnancy that is somewhat eccentrically located, or one that's quite eccentric because it's in a duplicated uterus, such as a bicornuate or septate uterus.

The way that we distinguish, you can see schematically, cornual ectopic has no visible myometrium around the lateral or superolateral aspect, where an intrauterine pregnancy that's eccentric will have myometrium all the way around it.

So if we see an eccentric sac or little or no visible myometrium, cornual ectopic, if there's myometrium around the entire sac, it's an intrauterine pregnancy.

And again, side by side examples here is a transverse or coronal view of the uterus. You can see an eccentric an eccentric gestational sac on both of these. But more important than just being eccentric is we see no hypoechoic myometrium around the lateral aspect. That's a cornual ectopic here.

On the other hand, there is transverse view of the uterus, very eccentric sac, way over towards the right side of the uterus. But you can see good hypoechoic myometrium all the way around it. This is an intrauterine pregnancy and a bicornuate uterus.

And the final kind of unusual ectopic is a pregnancy that's implanted in a cesarean section scar. You as seen here schematically. This is ectopic because it's not located where it should be in the body of the uterus in the mid within the uterine cavity in the endometrium or decidua. It's up here in a in the cesarean section scar.

That can sometimes be difficult to distinguish from a lower uterine segment implantation or a spontaneous abortion in progress where the pregnancy is in the lower part of the uterus.

To diagnose it, we wanna see the pregnancy coming all the way up to the serosal surface, or even sometimes bulging it.

So the diagnostic criteria for a pregnancy implanted and a c-section scar include a prior patient has to, of course, had a prior cesarean section. The gestational sac should be located low and anteriorly in the uterus just above the cervix and the gestational sac and the surrounding echogenic ring of trophoblastic tissue should extend to the serosal surface of the uterus to make the diagnosis, as in this case.

You can see this gestational sac is just is in the very lower part of the uterus, just above the cervix. And it looks like it's extending up to the serosal surface. You can see that better on this closeup view. There's a heartbeat. There's the serosal surface that's bulging a little bit by this with the trophoblastic tissue extending all the way up there. This is a pregnancy implanted in a cesarean section scar.

These are very important treat. Here. You can see a five and a half week pregnancy implanted in a cesarean section scar. Two and a half, two weeks later. It's seven and a half weeks. It's growing and starting to bulge the sac. The woman was advised to have this treated at this point because of concern for subsequent rupture of the pregnancy of the uterus, but she elected not to.

And by 11 and a half weeks, the uterus is bulging way out. And this was far enough along that the only way to treat this was via hysterectomy.

Conclusion

So I've come to the end of the discussion of emergency obstetrical ultrasound in the first trimester. Hope that it's been valuable to you in seeing the ways to accurately diagnose. The two things we're worried about in emergency scans in the first trimester, namely failed pregnancy and ectopic pregnancy.