Diagnosis of Early First Trimester Miscarriage - HD

Introduction

Hi, I am Dr. Peter dle, professor of radiology at Harvard Medical School, and senior Vice Chair of Radiology at the Brigham and Women's Hospital in Boston.

I'll be lecturing on ultrasound diagnosis of early first trimester miscarriage, talking about some of the ways to diagnose miscarriage and some of the errors to avoid making in the diagnosis of miscarriage.

Terminology and Incidence

First, a little bit of terminology.

A miscarriage is defined as spontaneous loss of an intrauterine pregnancy prior to 20 weeks of gestation.

What I'm gonna be focusing on here is early first trimester miscarriage, miscarriage between five and seven to eight weeks of pregnancy.

Some other terms that are synonymous with miscarriage, at least early first trimester miscarriage include early pregnancy failure or spontaneous abortion.

The incidence of miscarriage is fairly high, 10 to 25% of all clinically recognized pregnancies.

And in miscarriage, what do I mean by clinically recognized?

That's a woman who is known to be pregnant based on either a positive pregnancy test or an ultrasound showing a pregnancy.

It is really not possible to know how many of all pregnancies end in miscarriage, but it is almost certainly much higher than 10 to 25%.

Standardization of Criteria

This is an interesting statement that was made in an editorial in the journal ultrasound in Obstetrics and Gynecology in December of 2011, where the editorial writer stated, would it not be worrying if the criteria to pronounce death at any other stage of human life were as variable as those that exist currently in early pregnancy?

In other words, the editorial was expressing concern about the fact that in different practices within one country or in different countries, people used different criteria to diagnose miscarriage, whereas there should be standard criteria to diagnose miscarriage.

That was in 2011.

And in part because of concerns such as those expressed in the editorial about varying criteria to diagnose miscarriage, the Society of Radiologists in ultrasound put together a consensus conference on early first trimester sonography guidelines for diagnosing miscarriage, and excluding a viable intrauterine pregnancy that was held in October 23rd to 24th of the year 2012, to try to get a standardization of criteria for diagnosing miscarriage.

About a year after the 2012 consensus Conference, a paper came out from that conference published in the New England Journal of Medicine called Diagnostic Criteria for Non-Viable Pregnancy Early in the first trimester that I was the moderator of that consensus conference, the conference included radiologists, obstetrical obstetrician gynecologists and emergency medicine physicians, and I think it's had a significant impact.

The criteria from that consensus conference and from work of others has really gone a long way to standardizing the criteria for diagnosing miscarriage that are used all over the world.

Consequences of Misdiagnosis

One of the driving forces or very important considerations that we took into account and that have to be taken into account in diagnosing miscarriage, has to do with the consequences of false positive and false negative diagnosis of miscarriage in medicine.

Whenever we make we use tests to make diagnoses, there's always the chance of false positives and false negatives.

Now, no tests are perfect.

So for miscarriage, let's take a look at the false positive and negative diagnoses of miscarriage and what their consequences are.

So let's start with a false positive, a false positive diagnosis of miscarriage simply means the erroneous diagnosis, you make an error.

You say there is a miscarriage, but you're wrong.

There isn't.

What's the consequence of a of that kind of false positive?

Well, the consequence is pretty horrible.

The woman, if you make a false positive diagnosis of a miscarriage in a woman, she is likely to undergo a procedure such as uterine evacuation, evacuating out the contents of the uterus.

If you've diagnosed that there's a miscarriage in a woman who has a potential norm, a potentially normal intrauterine pregnancy, that is a really horrible consequence.

What about a false negative diagnosis of miscarriage?

What do I mean by that?

I mean, the you should diagnose miscarriage.

There is a miscarriage, and you should diagnose it, but you don't.

The negative consequence there is delayed intervention for a woman with a miscarriage or with a failed intrauterine pregnancy.

That's not great, but it's not so horrible.

False positive the consequences of a false positive diagnosis are much greater than the consequences of a false negative diagnosis.

So we really want to avoid false positive diagnoses.

So the criteria for diagnosing miscarriage should be set to eliminate false positives, to make sure that we never say to a woman you have a miscarriage when she really doesn't.

And criteria for miscarriage should also be set to apply to a broad range of ultrasound facilities that meet at least minimum quality criteria to be doing ultrasound.

And those criteria were not setting criteria that apply solely to experts in early obstetrical ultrasound.

Outmoded Concepts

The as we'll see as the talk goes on that the there are a number of outmoded concepts in early pregnancy that can lead to errors in diagnosis of miscarriage, or errors in diagnosis of what's going on in an early pregnancy.

Those outmoded concepts include pseudo gestational sac, some of the published signs of early pregnancy, including the double sac sign and intertidal sign.

Both of those concepts, the pseudo sac and the sonographic signs of early pregnancy are about 35 years old now from the early 1980s, and they're outmoded are obsolete now.

As we'll see, other outmoded concepts that lead to problems include overly lax criteria for miscarriage, such as an embryo measuring at least five millimeters with no heartbeat or a mean sac diameter measuring at least 16 millimeters with no embryo.

And finally, the notion of an HCG discriminatory level for excluding a normal intrauterine pregnancy is another outmoded or obsolete concept.

And we'll see as we move along this talk, why all of these are obsolete and what kinds of errors you can make if you use them.

Overview of Scenarios

So, we're gonna consider here three scenarios in the diagnosis of early first trimester miscarriage.

One is these are all in women with positive pregnancy tests.

Scenario one is when you don't see an intrauterine pregnancy, and you also don't see anything in the adnexa, that is known as a PUL, which stands for pregnancy of unknown location.

Another scenario in which we diagnose or try to diagnose miscarriage is when we see an intrauterine pregnancy as this small little fluid collection here represents, but there's no heartbeat diagnosing miscarriage in those settings.

And the third scenario that I will consider is when the ultrasound shows an intrauterine pregnancy with a heartbeat.

So the topics are going to that I'm gonna cover.

First, I'll briefly talk about normal ultrasound findings in the early first trimester, and then get into scenarios one, two, and three after that.

Normal Ultrasound Findings in Early First Trimester

So, let's start with normal ultrasound findings.

In the early first trimester, The ultrasound findings between five and seven weeks follow a very well-defined sequence with very little variation from patient to patient, from woman to woman.

These ages that are listed on this slide are what we see on transvaginal ultrasound.

Transvaginal ultrasound is the technique that should be used in the first trimester, especially when a an abnormality is suspected.

So what happens very predictably, as you can see on this slide, is that at five weeks we see a gestational sac.

That by five weeks, I mean the time since the number of weeks since the woman's last menstrual period, which is how we standardly define age or measure age in in pregnancy.

Gestational age is the same as what's sometimes called menstrual age, age since last menstrual period.

So at five weeks, we see a gestational sac at five and a half weeks, or very very close to that.

We see we first see the yolk sac at six weeks.

We first see the embryo with a heartbeat.

And then a week after that, at seven weeks, we start to see the amnion around the embryo.

So here our examples on ultrasound at five weeks, you can see the pregnancy looks like a little round or oval fluid collection in the central bright part of the uterus.

As seen here At five and a half weeks, we see a yolk sac, but still no embryo.

At six weeks, we're seeing this tiny little, this is one or two millimeters, this embryo we find, we see it at six weeks.

You can see the heartbeat within it.

And at seven weeks you can see that we're seeing not only the embryo and the yolk sac, but we're finally, we're seeing the amnion that is separate from the from the embryo.

Whereas the amnion back at six weeks, it's really right up against the embryo.

So we just don't see it.

It separates from the embryo in the normal pregnancy at seven weeks.

So these dates, five weeks, five and a half weeks, six weeks, seven weeks are very very precise from woman to woman.

Diagnosing Early Intrauterine Pregnancy

So how do we actually diagnose an early intrauterine pregnancy?

Well, in a woman with a positive HCG who has a little intrauterine fluid collection on ultrasound, if that fluid collection contains a yolk sac or an embryo, we know it's a gestational sac.

But an important question is if the fluid collection does not contain a yolk sac or embryo, how can we tell whether it is a gestational sac?

And here's an example.

This is a woman who has a history of pelvic pain.

Her HCG, her pregnancy test measures at 1800.

And on ultrasound we see a little small non-specific fluid collection in the uterus.

By non-specific, I mean, it doesn't have any particular features or signs.

It's just sitting there in the middle of the of the uterus.

Her adnexa were normal on other images.

So again, positive pregnancy tests at 1800 small little non-specific fluid collection in the uterus with normal adnexa.

So think about for the next few minutes, we'll get the answer soon.

Is the most likely diagnosis here an intrauterine pregnancy?

Or does this woman with a positive pregnancy test is the most likely diagnosis an ectopic pregnancy with a pseudo gestational sac, or an ectopic pregnancy with a deci cyst?

Or may or should you say, I just can't tell.

And if I were issuing a report on this patient, should you should your report say, I can't tell the findings are consistent with either intrauterine pregnancy or ectopic pregnancy?

Right around the late 1970s, early 1980s, two sonographic signs of early intrauterine pregnancy were published, the so-called double sac sign, which you see here, little fluid collection surrounded in part at least by two bright rings.

And if you look at the diagram, remember that pregnancies don't, are not situated in the cavity of the uterus.

That's that little black area.

He down here.

They're they are burrow into, they're situated within the decidua, which is really just the endometrium of the uterus.

So the double sac sign arises when you see a ring here and a ring here surrounding at least part of that fluid collection.

That's a double sac sign.

Or in other patients, what you may see is this little white line, which corresponds to the collapsed uterine cavity, and the fluid collection sitting beside it.

So here is that thin white line, little fluid collection beside it.

And that tells us that the fluid collection is not in the cavity, but in the decidua or the endometrium.

So those two signs were published 35 years ago, but today we see pregnancies very early.

And many pregnancies, we'll see how many very shortly, many pregnancies have no sign.

This is an early pregnancy.

How do I know it's an early pregnancy?

Because she came back short while later, not too many days later, and there was an embryo with a heartbeat, which we're not seeing here.

So this is what I would call a pregnancy with no sign.

It's just a non-specific sac, like fluid collection in the middle of the uterus.

So how do we know whether something like this is a pregnancy or a what used to be called a pseudo gestational sac?

'cause after all, we don't see a y an embryo, we don't see a yolk sac, we don't see a double sac sign, we don't see an intertidal sign.

How do we know what it is?

Well, to try and answer that question, we in our own department in Boston did two different studies.

We looked in intrauterine pregnancies, how often they had a non-specific sac like structure, and not a double, no double sac sign or no intraprocedural sign.

And we found that about 50% of early intrauterine pregnancies today look like a nonspecific sac like structure Does.

How often does an ectopic pregnancy also have a little nonspecific sac like structure in the uterus?

Well, we found that with ectopic pregnancies, most women have no fluid in the uterus.

Some patients have little bit of irregular fluid that doesn't look like a pregnancy.

And about 3% of ectopic of women with ectopic pregnancies have a similar kind of nonspecific sac like structure in the uterus.

So you can see when you look at comparing this piece of the pie to this piece of the pie, most nonspecific sac like structures are actually intrauterine pregnancies.

Very few of them are ectopic pregnancies.

But if you also factor in the relative incidences of intrauterine versus ectopic pregnancies, 98% of pregnancies, at least in the United States, our intrauterine only 2% are ectopic.

Now, compare the size of this piece to this piece, and you'll see that almost every time you see a non-specific sac like structure, it's an intrauterine pregnancy.

Very rarely is it a sign of ectopic pregnancy.

And if we do a little calculation based on these numbers, the incidence of ectopics in all pregnancies is 2%.

50% of early intrauterine pregnancies appear as a non-specific sac like collection in the uterus.

And 3% of ectopics have that kind of appearance.

If we do a little math, we can see that an isolated sac like fluid collection in the uterus.

By isolated, I mean, there's no adnexal mass of an ectopic pregnancy.

Anytime you see an isolated sac like fluid collection in a woman with a positive HCG, there's an over 99 chance, not over 99% chance that it's a gestational sac, less than 1% chance that it's a pseudo gestational sac or a deral cyst.

And therefore, basically any time you see an isolated sac like fluid collection in a woman with a positive pregnancy test, it's almost certain to be a gestational sac.

It's a highly likely gestational sac in such a patient.

And whenever you see a little fluid collection in the uterus in a woman with a positive pregnancy test, and nothing in the adnexa, any treatment that could damage an intrauterine embryo such as methotrexate or a DNC procedure, any such treatment should be avoided unless a normal intrauterine pregnancy is definitively excluded at some future time.

So, I posed this question a few slides ago.

This woman has an HCGA pregnancy test measurement of 1800.

She has a small non-specific fluid collection in the uterus.

What's the most likely diagnosis?

It's an intrauterine pregnancy, none of the others.

And 16 days later, there's the embryo with a heartbeat.

So these kinds of things in women with positive pregnancy tests are virtually always intrauterine pregnancies.

Scenario 1: Pregnancy of Unknown Location

Okay, so let's move now to diagnosing miscarriage.

Now that we know that what early pregnancies look like, they really look like any little fluid collection in the uterus.

Let's look at diagnosing at scenario one of diagnosing early first trimester miscarriage where you see nothing in the uterus.

So the setting here is ultrasound shows no intrauterine pregnancy and shows no ectopic pregnancy in a woman with a positive HCG, she has a pregnancy of unknown location 'cause we don't see it inside the or outside the uterus.

And the main question here, can a single HCG value the discriminatory level, diagnose or exclude any one of a normal intrauterine pregnancy and miscarriage or ectopic?

Is that discriminatory level that's been described?

And we'll see in a minute what it means.

Is it useful to diagnose, to conclude what's going on?

So what is the HCG discriminatory level?

It's a concept that was originated by Nicholas CA in 1981, 35 years ago, 34 years ago.

And it's defined as the HCG level at or above which a normal intrauterine pregnancy is consistently seen.

In 1981, CDR reported the discriminatory level to be 6,500, which meant that in other words, he found that in women with normal intrauterine pregnancies, you always saw a pregnancy in the uterus on ultrasound.

If the HCG was 6,500 or above, as ultrasound technology improved, the discriminatory level dropped the level at which we always see an entry uterine pregnancy, if there's a normal one dropped.

And since about 1990 when transvaginal ultrasound became commonly used in early pregnancy, the discriminatory level has been reported to be in the one to 2000 range.

In other words, if we take the higher number by the time an HCG the HCG is at least 2000, if the discriminatory level works by the time it's 2000, you should always see a pregnancy in the uterus if there's a normal pregnancy.

So the rationale just by pictures, is that if the HCG is greater than 2000, and you see no intrauterine fluid collection, the rationale for the HCG is that in that kind of situation, the woman can't have a normal intrauterine pregnancy, the differential diagnosis than in a woman with an HCG above 2000.

And nothing in the uterus would be either a failed intrauterine pregnancy, a miscarriage, in other words, or an ectopic pregnancy.

And based on that rationale, at least two different management algorithms came into common use.

First said, if the HCG is above the discriminatory level and you don't see an intrauterine pregnancy, you should do A DNC.

And if you don't see any Chorionic VII on the DNC treat for ectopic pregnancy, and another management algorithm that is was proposed is if the HCG is above the discriminatory level, usually taken as 2000, and you don't see an intrauterine pregnancy, just go straight to intramuscular methotrexate for a presumed ectopic pregnancy.

Well, that's the theory and the rationale.

But here's the reality.

Here's a woman, an ultrasound, a woman whose HCG is over 4,000.

More than double, they usually considered a discriminatory level of 2000.

No, there's no visible gestational sac if the discriminatory level of work, this woman couldn't have an a normal intrauterine pregnancy.

But look, a month later, she has a normal nine and a half week intrauterine pregnancy and ended up with a normal term baby.

So the discriminatory level did not work in this woman and in many others for rolling out a normal intrauterine pregnancy.

And therefore, with respect to the HCG level and pregnancies of unknown location, in other words, the HCG level in women with no visible intrauterine or ectopic pregnancy, the important rule to follow is that if ultrasound shows no evidence of an intrauterine or ectopic pregnancy don't intervene based on a single HCG measurement.

And that's because a single HCG measurement, even if above, what's what's sometimes called the discriminatory level, does not rule out a normal intrauterine pregnancy.

It's important to get at least one follow-up ultrasound and HCG in order to avoid damaging a potentially normal intrauterine pregnancy or giving methotrexate unnecessarily to a woman with a failed intrauterine pregnancy.

Scenario 2: Intrauterine Pregnancy Without Heartbeat

Okay, let's move on to scenario two in diagnosing miscarriage where you do see an intrauterine pregnancy, but you don't see a heartbeat.

So, scenario two, just to state the what we're looking at here.

The ultrasound shows an intrauterine pregnancy.

There's no heartbeat seen, maybe just no embryo or an embryo with no heartbeat.

The questions there are in scenario two, what findings indicate a definite miscarriage and what findings are suspicious for miscarriage?

So there are really three different criteria for pregnancy failure or miscarriage on ultrasound.

One is failure to visualize a heartbeat by a certain embryonic size.

In other words, a crown rum length without a heartbeat.

Another is failure to visualize an embryo by a certain gestational sac size.

In other words, a mean sac, diameter without an embryo.

And a third type of criteria for miscarriage are failure to see an embryo by a certain point in time.

And that's usually defined as no embryo seen after some time interval since an initial ultrasound.

So the criteria up to about 2012 that were in pretty broad use were a crown romp length of at least five millimeters without a heartbeat indicated definite miscarriage, a mean sac diameter of at least 16 millimeters without an embryo indicated definite pregnancy failure.

And there were no well-established criteria for non visualization of an embryo by a certain point in time.

So let's look at each of these, the crown rum length.

With respect to the crown rum length, the heartbeat is usually seen as soon as a as soon as the embryo is visible.

There's a there should be, this is a crown rum length of 1.7 millimeters.

Should be seeing a heartbeat here as we do right now.

But the to diagnose miscarriage with certainty, the question isn't that we should be asking is not when we usually see a heartbeat, but when we always see a heartbeat at what crown rum length, do we always see a heartbeat if the pregnancy is normal?

So some of the so in other words, what's the cutoff value of the crown rum length above which cardiac activity is always visible on transvaginal ultrasound in a normal pregnancy.

And early studies in around 1990 suggested four or five millimeters.

In other words, those early studies indicated that by the time the crown rum length is four or five millimeters, if you don't see a heartbeat, it's never gonna be there.

It's a miscarriage.

So five millimeters became the generally di accepted cutoff for diagnosing miscarriage.

But what we've come to realize over the last few years is that five millimeters is not good enough.

Occasionally studies have reported women with whose ultrasound shows a six millimeter embryo with no visible heartbeat, who then came back on follow-up and everything was fine.

So the SRU consensus panel in 2012, and the publication in 2013 raised the cutoff from five millimeters to seven millimeters, stating that the new criteria for miscarriages a crown rum length of seven millimeters or greater, and no heartbeat being definitive for miscarriage.

And then if you have a crown rum length, anything under seven millimeters, and there's no heartbeat, it's highly suspicious for miscarriage.

Just a couple of examples.

Here's a seven millimeter embryo on the video clip.

There's no heartbeat that shows definite miscarriage.

Here is a four millimeter embryo with no heartbeat.

That's suspicious for a miscarriage.

What about the mean sac diameter here?

The question is, what is the cutoff value for the mean sac diameter above which an embryo is consistently visible on a transvaginal ultrasound in a normal pregnancy.

Early studies suggested that by the time the mean sac diameter was 16 or 17 millimeters, you always see an embryo if the pregnancy is normal.

So 16 millimeters became the generally accepted cutoff for diagnosing miscarriage.

In other words, if you have a 16 or greater millimeter embryo mean sac diameter and you didn't see an embryo, you could diagnose miscarriage with certainty.

But again, studies around the year 2010, a couple of years before or after showed that that 16 millimeters was not good enough.

There have been reports of mean sac diameters greater than 16 millimeters, a little greater than 16 millimeters with no embryo.

That proved to be normal on follow up.

So the SRU consensus panel increased the cutoff from 16 millimeters with no embryo to 25 millimeters, and no embryo being definitive for miscarriage.

Anything between the old cutoff of 16 millimeters and 24 millimeters in the absence of an embryo is suspicious, but not definitive for miscarriage.

So here is an example of a definite miscarriage.

We have three measurements of this gestational sac, 1, 2, 3.

We average them 27.7 millimeters, no embryo that's bigger than the cutoff of 25 millimeters.

This is definite for miscarriage.

Here we take the three measurements.

We average them, it's measuring 16.8 millimeters and there's no embryo.

This is suspicious, but not definite for miscarriage.

And then the SRU consensus conference also came up with some time-based criteria for miscarriage.

If you see a gestational sack without a yolk sack, in other words, one of those little tiny fluid collections on an initial scan, and then there's still no embryo at least two weeks later, that's definitive for miscarriage.

If you see on the initial scan a gestational sac with a yolk sac, and you still see no embryo 11 days later, that is definitive for miscarriage.

And then some different time criteria for to be suspicious for miscarriage.

Here's an example, based on time-based criteria of a definite miscarriage.

On initial scan, we see a gestational sack with a yolk sack.

12 days later, we're still seeing a yolk sack, but there's no embryo that is more, that 12 days is above the 11 day cutoff.

So this is a definite miscarriage.

And there are a couple of other ultrasound criteria that are suspicious for miscarriage.

One is an empty amnion.

The amnion is adjacent to the yolk sac, and there's no embryo or a large yolk sac.

Here's an empty amnion.

We see two little circles.

One is a yolk sack and one is an amnion.

I'm not even sure which one, but remember from an earlier slide where I showed you the normal progression of ultrasound findings in pregnancy.

We normally see the embryo at six weeks, the amnion at seven weeks.

The amnion, in other words, comes after the embryo.

Here we're seeing an amnion with no embryo, so it's abnormal, suspicious for miscarriage.

And here are a couple of different pregnancies with a large yolk sac, bigger than six or seven millimeters that are suspicious for miscarriage.

And here is a full listing of all of the diagnostic criteria that are definite for pregnancy failure or suspicious for pregnancy failure.

And these come from our New England Journal article publication.

Scenario 3: Intrauterine Pregnancy With Heartbeat

And the final scenario that I will consider scenario three is diagnosing miscarriage or at least impending miscarriage when you see an intrauterine pregnancy with a heartbeat.

So here the question is, what findings suggest impending miscarriage, a miscarriage about to happen within the next few days?

If an ultrasound shows an intrauterine pregnancy with a heartbeat, there are a number of findings that suggest impending miscarriage, such as a slow or irregular embryonic heartbeat, a large subchorionic hematoma, and some others.

I'll go through these briefly.

First, early heart rate.

The main numbers to remember here are that very early on, up to about 6.2 weeks of pregnancy or up to a crown rum length of four millimeters, the heart rate is slow if it's less than 90 beats per minute.

And it's normal.

If it's at least a hundred beats per minute.

If there's a slow heart beat that is suspicious for impending miscarriage, there isn't a miscarriage yet 'cause there's a heartbeat.

But it's suspicious for impending miscarriage.

When the crown rum length is five to nine millimeters, anything under 110 beats per minute is suspicious for impending miscarriage.

And here's an example.

You can see this embryo with a heartbeat.

Four millimeter embryo with a heartbeat.

It's going at 82 beats per minute kind.

It looks slow to our eyes going at 82.

This is very suspicious for impending miscarriage.

And sure enough, five days later on this clip, there's no heartbeat.

Now here, if you look, you can see beat, beat, stop, beat, beat, stop, beat, beat, stop on the M mode, beat, beat, stop, beat, beat, stop.

This is an irregular embryonic heartbeat, also suspicious for impending miscarriage.

What about when we see a subc chorionic hematoma in conjunction with a heartbeat?

So we do an ultrasound, we see an embryo with a heartbeat inside a gestational sac, but there's a hematoma around the sac.

What is the clinical significance of that?

Subc hematomas have been classified as small, medium, or large based on subjective assessment, what it looks like based on the fraction of the gestational sac that's surrounded by hematoma, is it a quarter surrounded a half surrounded, all surrounded by hematoma or the estimated volume of the hematoma?

Whichever method where you use, subc, chorionic hematomas can be classified as small, medium, or large.

Most studies of sub chorionic hematoma in the presence of an embryonic heartbeat have found that a large subc chorionic hematoma carries a somewhat elevated risk of subsequent miscarriage, likelihood of miscarriage around 20 to 40%.

So in other words, if you see an ultrasound today and there's a heartbeat and there's a large subc chorionic hematoma around the gestational sac, there's about a 20 to 40% chance that the pregnancy will miscarry.

There's still a 60 to 80% chance that it will do fine.

But about a third of those cases with a large subchorionic hematoma and a heartbeat will miscarry a small to moderate subc chorionic hematoma really doesn't mean anything.

If there's a heartbeat, they carry little or no added risk of miscarriage happening.

So here's a case where you see a heartbeat right here.

But there's a pretty large subchorionic hematoma.

Here's one part of it.

That's that same part.

It also goes around here.

Really, all of this part of the gestational sac is surrounded by a subc chorionic hematoma.

This is a large subc chorionic hematoma measured by any of the methods that I showed on the prior slide.

This is suspicious for impending miscarriage.

On the other hand, this is a small to moderate subc chorionic hematoma.

There's a heartbeat.

There's a little or no risk to this pregnancy.

And five weeks later, you can see everything looks fine.

We sweep through and the hematomas all gone so small to moderate.

Subc chorionic hematomas really don't mean anything.

Another finding that is suspicious for impending miscarriage is a small gestational sac size.

When there's a heartbeat, here's an embryo.

You can see the fetal head, the body, the heartbeat.

But this the sack is hardly bigger than the embryo, very little fluid around the embryo.

That's a very worrisome finding.

This was just over seven weeks.

So this is worrisome for impending miscarriage.

And in fact, there was a demise on a follow-up scan.

Six days later, another finding in conjunction with heartbeat that's suspicious for impending miscarriage is an expanded amnion.

Again, the amnion normal app normally appears at six and a half to seven weeks, usually seven weeks when the crown rum length is close to 10 millimeters.

If we see an amnion, when the crown rum length is less than five millimeters, there's a very high chance of subsequent miscarriage, as in this case.

Here you can see there's a heartbeat on this clip.

There's the yolk sac, but what's abnormal is there is the amnion around it.

Even though the crown rum length is only about three millimeters, you really shouldn't see it until it's close to 10 millimeters.

You shouldn't see the amnion.

This is highly worrisome.

And in fact, a week later on this clip, there's no longer a heartbeat.

I said earlier that a enlarged yolk sac bigger than six or seven millimeters when it's seen alone, is worrisome for miscarriage.

If you see an enlarged yo sack in the presence of a heartbeat, it's suspicious again.

But now for impending miscarriage, here's an embryo with a heartbeat going.

Nice, normal rate.

But the yo sack's too big.

The oak sac is nine millimeters bigger than the six or seven upper limit of normal.

And on follow up, there was a demise follow up a month later.

Summary

So just to summarize, in a woman with a positive pregnancy test and no adnexal mass, if the ultrasound shows no intrauterine fluid collection, so there's no adnexal mass and no intrauterine fluid collection, she has a pregnancy of unknown location.

It's important not to intervene before getting a follow up HCG and ultrasound.

If the ultrasound shows an intrauterine fluid collection with rounded edges, it's likely an intrauterine pregnancy.

So don't intervene.

And if the ultrasound shows an intrauterine pregnancy and no cardiac activity, don't intervene unless the ultrasound findings meet very strict criteria.

The seven millimeter crown rum with no heartbeat, or the 25 millimeter with no embryo, don't intervene unless the ultrasound findings meet strict criteria for failed pregnancy.

Notice the don't intervene.

Don't intervene, don't intervene, don't intervene unless you're really really sure that it is a miscarriage.

The bottom line message is first, do no harm to early pregnancies.

Thank you.