Threatened Abortion - SD

Indications for First Trimester Sonography

There are three major indications for sonography in the first trimester of pregnancy.

These are dating, threatened abortion, and ectopic pregnancy of the pathologic reasons to get a sonogram in the first trimester.

Threatened abortion is number one.

What I'd like to do today is to talk to you about a new look at so-called cutoff values for making diagnoses of failed pregnancies.

Advances in First Trimester Pregnancy Information

There has been a veritable explosion of information regarding the first trimester of pregnancy in the last 15 years.

This is predominantly due to the fact that assisted reproductive technologies have taken such a strong foothold in gynecologic and obstetrical medicine.

Our sources of information are based on the ability to detect extraordinarily small levels of human chorionic gonadotropin.

Additionally, chorionic villus sampling has given us a new look at a large number of potential chromosome aberrations that are seen during the first trimester of pregnancy.

And then of course, high resolution endovaginal sonography has enabled us to take a look at the developing pregnancy in a much more detailed way than we ever were able to do so in the past.

What we have learned from all of this information is that human pregnancies are actually lost at a considerably greater rate than we previously had thought.

Pregnancy Loss Rates

If one takes a hundred women undergoing exposed fertility, women who are menstruating normally and are not taking any form of birth control techniques, we find that during the course of a month, upwards of 80% of those women will in fact get pregnant and develop a zygote.

However, a number of these zygotes will simply pass through the uterus into the vagina and never successfully implant.

Once the zygote implants and is present for two or three days, it is producing sufficient human chorionic gonadotropin to be detected by sensitive techniques.

However, at this point, the patient does not yet know that she is pregnant.

This is termed a chemical pregnancy.

Unfortunately, we now know that many of these pregnancies, which can be detected chemically, are promptly lost at or about the time that the patient is anticipating a menstrual period.

Therefore, as far as the patient realizes she simply had a menstruation, although in fact this was something called a menstrual abortion.

So very often in women undergoing unprotected intercourse who are normally ovulating, that late period may very well represent a menstrual abortion rather than simply a late onset of the menses.

It isn't until these processes are complete and the woman misses a menstrual cycle, either buys a pregnancy test at her local drug store, or consults her obstetrician and obtains a pregnancy test through that mechanism that we have something that can be called a clinical pregnancy.

And it isn't until this point that there is actually a human investment in the outcome of that pregnancy.

However, even at this point, there are still many losses that will be undergone depending on which articles from the literature you believe menstrual abortions are occurring at a rate somewhere or between the high 20% and 40% of such pregnancies.

And you can see, however, from this point, the loss rate will approach baseline asymptotically to reach its baseline level of loss, generally somewhere around one half to 1% of pregnancies.

Now, this may sound rather sad, this high loss rate of early pregnancies, but importantly, it is an entirely natural phenomenon.

Most of these losses are secondary to severe chromosomal abnormalities.

A significant proportion of the residual are lost because of single gene lethal mutations.

So from this point at which we have a clinical pregnancy, a pregnancy in which there is now a significant human investment from this point onward, this is what we observe medically and in sonography as pregnancy losses that result in spontaneous abortion.

Threatened Abortion

What we're going to talk about is the clinical syndrome known as threatened abortion, which consists of either all three or two of the three of the following entities, early bleeding, mild cramping in the presence of a closed cervical os.

Again, importantly, this is a clinical syndrome and not a sonographic diagnosis.

So you do not want to send back a report that says threatened abortion because you see something that is concerning to you.

In fact, the term abortion is seen in many forms in early pregnancies and is very often not appropriately used.

The term is not appropriately used.

Imminent abortion is an impending abortion in which bleeding is profuse and the cervix is softened and dilated and inevitable.

Abortion is an abortion in progress where the pregnancy is actually proceeding out of the uterus and through the cervix.

A missed abortion is the retention of a dead pregnancy for at least two months.

This term is commonly misused both by the clinician referring the patient and by the sonologist rendering a report on a pregnancy that they feel has failed.

It is essentially impossible for us to know that the pregnancy has been dead for at least two months.

Incidence of First Trimester Bleeding

If we look at some recent large studies that look at the incidence of first trimester bleeding, we can see that in 5,800 women studied by Axelson, approximately 28% registered a report of bleeding.

Everett in a 550 woman prospective study found 21%.

So essentially what you can say is that approximately 20% of women will have threatened abortion in the first trimester of pregnancy.

Now, importantly, 59% of those women in Everett's study went on to miscarry.

These numbers are actually very similar to the classical estimates that you could find in obstetrical textbooks 20 and 25 years ago.

And the reason for that is because the cause remains unchanged and is unlikely to change chromosome anomalies and single gene lethal mutations.

The only reason that these numbers in fact have crept up in recent years is because women are holding off on pregnancy until later age.

The later age increases the likelihood of a chromosome abnormality and therefore the potential for a first trimester loss.

Importantly, we should all realize that threatened abortion is not a threat to the physical health of the mother.

It's not a serious threat anyway.

There are some threats, but they're relatively minor.

Therefore, uterine evacuation is not a medical necessity, and in fact, there is an increasing trend not to mechanically evacuate the uterus in these women because every instrumentation of the uterus results in some degree of damage to its lining.

It is, however, a definite threat to the psychological health of the mother.

Once the mother knows she is pregnant, she is very invested in this pregnancy and the onset of bleeding is a very serious psychological threat to her.

If the pregnancy is lost.

It is important to realize that grieving is inevitable, it's human and not something that we would want to interfere with.

So the best that we can do for this mother is to come to a firm conclusion about this unfortunate episode that she is experiencing.

Dating the Pregnancy

One of the problems that we encounter is that it is difficult to judge the accuracy of menstrual age in a woman who is threatened to abort.

After all she is bleeding and therefore that complicates the notion of the last menses.

Additionally, when the uterus is examined by palpation by the clinician, it is often small for dates.

The reason being, as you will see as we go through this lecture, many of these pregnancies are already dead and therefore the uterus is not growing at a normal pace.

It is therefore my propensity not to really rely on the patient's stated menstrual age.

There are, of course, extremely reliable dates for which the scientific validity is established, and these of course include women who are undergoing assisted reproduction.

So if she's had artificial insemination, in vitro fertilization or any other reason to have had ovulation induction, then these dates are absolutely rock solid, even more solid than we could obtain by doing early sonography.

In the absence of one of those well-established ways of dating the pregnancy, I use what is called the minimum menstrual age as opposed to the menstrual age.

The minimum menstrual age is calculated in the following way.

I don't ask the woman when was her last menstrual period.

I ask her, when did you get your first positive pregnancy test?

Realizing that it's going to take approximately four weeks for the woman to be tested and recognize that she is pregnant.

I then take the weeks that have elapsed since the pregnancy test and add four to that, and that is the minimum menstrual age.

So if the woman had her pregnancy test two weeks ago, then I can state with a high degree of scientific probability that she is at least six weeks along.

If her pregnancy test was performed three weeks ago, then I can say with a high degree of confidence that she's seven weeks along.

Sonographic Expectations for Embryo and Heartbeat

Once we are to seven weeks, we know that the patient should manifest a visible embryo with a heartbeat on sonography.

Indeed, a heartbeat must be visible by a minimum menstrual age of seven weeks.

And in fact, we can often see heartbeats at gestational ages less than six weeks.

So, what I can say is that some individuals use six as a cutoff.

That's perfectly fine.

I still use seven weeks as a cutoff for being able to invariably identify an embryo with a heartbeat.

You can see that at a menstrual age of 49 days or seven weeks, we should be looking at an embryo that is at least one centimeter long.

Such embryos invariably demonstrate a heartbeat.

Indeed, we typically identify embryos by five millimeters, and at five millimeters they should have a heartbeat.

So somewhere between six and seven weeks, we should almost invariably be able to identify an embryo with a heartbeat.

We will revisit this theme of the five millimeter embryo many times during the course of this lecture.

Short of these things, I make all of my observations based on mean sac diameter.

I'm sure you're familiar with the computation of mean sac diameter.

It is the length, width, and depth of the gestational sac divided by three.

Importantly, this is measured from the fluid chorion interface, so we do not include any of the wall when determining the mean sac diameter.

Once we have identified the gestational sac and measured its mean sac diameter, we know that the mean sac diameter in a normally growing pregnancy will increase approximately one millimeter a day.

Similarly, once we have identified an embryo and measured its crown rump length, we know that that embryo will also increase in size in crown rump length by approximately one millimeter per day.

So here you can see from Dia's data that the mean sac diameter during this critical period is increasing a millimeter a day and the crown rump length is also increasing approximately a millimeter a day.

Evaluation in Threatened Abortion

When a woman is threatening to abort, the clinician can in fact use a variety of means to establish the health of the pregnancy or the reverse.

However, sonography is the pivotal examination in this context because once a sonogram is done, most often we will know what is going on with that patient's pregnancy within 20 minutes of the onset of that examination.

Importantly, I would like you from this day forward to always think of how you are going to evaluate this pregnancy either in this limb where you either see an embryo or a fetus, or you do not see an embryo or a fetus.

Those are two entirely different thought processes.

Study of 600 Patients

We're going to look at 600 patients that we are studying recently.

These patients constitute a hundred percent of the cases that we saw sequential number of patients 600 in a row in whom sonography was performed.

An embryo or a fetus was identified in 77% of these and no embryo could be identified in the remaining 23%.

So generally speaking, three quarters of the time you will see an embryo when you do a sonogram under the circumstance of examining a patient who is threatening to abort and a quarter of the time you will not.

We will look at this group of patients first.

Detection of Embryos

With transabdominal sonography, we were able to consistently detect embryos when they were 10 millimeters long.

Endovaginal sonography enables us to consistently detect embryos that are five millimeters.

Again, we see this relationship of five millimeter embryo.

Obviously, we commonly detect embryos that are even smaller than five millimeters, but here we are talking about consistent detection of embryos.

So unless there is some overwhelmingly difficult technical problem, we anticipate being able to find all five millimeter embryos.

Now, importantly, in an early embryo, the structure of the embryo is simply globular.

And if it were not for this little heartbeat, it would be might be difficult to be absolutely certain that one is looking at the embryo itself.

A big help is that when you're looking at very tiny embryos, the yolk stalk has not yet developed, therefore the embryo will lie immediately adjacent to the yolk sac.

And indeed the heart lies immediately adjacent to the yolk sac.

As you can see in the example on the right, the problem that we run into is that the percent survival of tiny living embryos, those less than seven weeks, is much lower than for later embryos.

Survival Rates Based on Gestational Age and Bleeding

If you look at this chart, these are now women who are not bleeding.

These are normal women who are undergoing a pregnancy, and you can see that if you are examining them at five weeks menstrual age, the loss rate is going to be substantially greater than if you are examining them at nine weeks menstrual age.

There's nothing that we can do about this.

This is the natural history of early human pregnancy.

This data is gathered from a variety of sources and constitutes more of my interpretation of the literature than trying to simply feedback other people's data.

Basically, once you are out to about 10 weeks menstrual age, you are at the baseline loss rate of pregnancies, which is going to be somewhere between one and 2% in women who are bleeding.

It is well established that approximately 4% of these patients will undergo spontaneous abortion at seven to nine weeks.

A well-established number is about a 5% loss rate in women who are not bleeding, and approximately 10% in women who are bleeding at less than six weeks.

It's about 16% in women who are not bleeding.

And there are a variety of numbers offered for those that are bleeding, but 33% is my take on the literature.

About a third of these women will lose their pregnancy.

So what you can say is that women who are bleeding have about twice the loss rate of women who are not bleeding.

So what we basically are seeing is a shift of the curve in this direction toward a higher loss rate, and that loss rate is going to be about twice the loss rate that would be anticipated in women who are not bleeding.

Now, again, this may sound like bad news, but an important correlate of this is that women who have lost a pregnancy in the first trimester actually have a very high success rate in subsequent pregnancies.

And if you take that woman, the woman who has lost a first trimester pregnancy and compare her to a woman who has never been pregnant, she actually has a higher degree of success in a subsequent pregnancy.

The reason being that many women who have never been pregnant may in fact be infertile.

Now, I've already explained to you that I do not like to trust the woman's last menstrual period, and I would rather base my observations on actual sonographic observations.

So this is very helpful.

Goldstein's data from the mid nineties wherein if you see that there is a sac, about 11% of those women will subsequently lose their pregnancy.

If you see a yolk sac, it drops to 8.5% and the greater the size of the embryo, the closer you get to baseline loss rates around 1%.

So once the embryo is greater than 10 millimeters, you have, the woman has an extremely good chance of having a successful outcome to her pregnancy.

Patients with Visible Embryo

So recall that in these 600 patients, three quarters we could see an embryo, and one quarter we could not.

We'll now take the limb where we see the embryo and we will convert that into a hundred percent of the circumstances where we can see the embryo.

When we are examining a woman who is threatening to abort in this group, we are going to see a heart rate two thirds of the time, 68%, and one third of the time we will not be able to identify the heartbeat in the embryo.

What we can say is that in this group, the course of action will always be to observe the pregnancy.

It is in fact this group of women who have constituted a very large field of study in recent years regarding first trimester pregnancies.

Because of this issue of higher loss rates in earlier pregnancies, even though the embryo has a heartbeat, this has led to a lot of studies to try to predict which embryos.

Two thirds of these women will demonstrate a heartbeat when they're examined sonographically and unambiguously.

In this situation, we are going to observe the pregnancy for further growth and development.

It is this issue that we have already discussed that the loss rates of earlier pregnancies, even though there is a heartbeat, is still relatively high.

And this has led to a body of research over the past decade, which has looked very carefully to try to predict which of the embryos that is currently alive is most likely to subsequently go on and die.

And many such studies have been done, and they have identified a variety of poor prognostic features, large subchorionic hematoma, heart rates less than 80 beats per minute, and abnormal sac size relative to embryo size.

That is the sac looks too big or too small for the size of the embryo, or they have been correlated with HCG levels and the patient either shows an abnormally high or low level of HCG compared to the sonographic observations on that day.

Prognostic Features

Subchorionic Hematoma

Subchorionic hematoma has been studied many times and is not something that I am particularly in favor of observing.

Basically what we have is a reestablishment of the endometrial canal and the blood has accumulated within the endometrial canal between the chorion and the decidua vera.

Now, rather than size alone, it's my opinion that like real estate, it's location, location, location.

So in this instance on the left, you can see that indeed the placenta remains well attached in this patient.

Here's the developing placenta, and there's only a slight undercutting of the edge of the placenta to cause this subchorionic hematoma.

Whereas in this patient you can see that the placenta has been remarkably undercut by the hematoma.

And even though these hematomas are about the same size, there's no question in my mind that the prognosis of the one on the right is much worse than the prognosis of the one on the left.

Sac Size to Embryo Size

Another observation is the sac size to embryo size.

Here we have an embryo that's relatively small for the size of this large chorionic cavity.

Contrast that to these cases where we see the embryo and the size of the sac relative to the embryo is too small.

The actual definition of sac too small is that the mean sac diameter minus crown rump length is five millimeters or less.

Slow Embryonic Heartbeat

Here we have a nice example of a slow embryonic heartbeat, less than 80 beats per minute.

While all of these things are troubling to see, the bottom line is that identification of an embryonic heartbeat overrides all other features which suggest a poor outcome.

So despite the fact that the heartbeat may be slow, if there is a heartbeat, one will invariably follow that pregnancy.

Here is a very nice example of a very large subchorionic hematoma.

Would we be concerned about that?

Of course, but would we change management based on that?

Definitely not.

And you can see that this pregnancy went on to develop perfectly normally here one can see a very small sac.

You can only just see a yolk sac and a remarkably large subchorionic hematoma.

But here is the follow-up sonogram, late in the second trimester, perfectly normally developing fetus and pregnancy.

Features Associated with Poor Outcome

So which features most strongly are associated with a poor outcome?

Well, first is the greater age of the mother.

Any of these observations in a woman who is over 35 suggests a much poorer prognosis than in a woman who is younger than 35 earlier age of the pregnancy.

No matter how you look at it, we are further back on that asymptotic curve and the loss rates will be higher.

The two most important of these observations in my opinion, are the heartbeat less than 80 beats per minute, which is a very poor prognostic indicator and a sac too small, another very poor prognostic indicator.

Importantly, these are not independent variables because you are more likely to observe these in women of greater age or earlier in at an earlier stage of pregnancy.

In these instances, importantly, a follow-up sonogram is not required.

Many times the obstetrician will want to get a follow-up sonogram in women who have shown a poor prognostic indicator, but it is not required that we follow these patients.

If we look at the actual numbers of these, among these 600 patients, 462 had an identifiable embryo among whom 314 had a heartbeat visible and 147 did not.

Among the 314 that had an embryo with a heartbeat, the embryo was less than five millimeters in 53 of those or 17%.

So quite naturally, this is a group wherein one would anticipate that the loss rate would be higher.

Importantly, endovaginal sonography can detect human embryos prior to the onset of cardiac contractility.

This is actually a rather remarkable statement, but it's been shown several times in the literature during studies that embryos that are smaller than five millimeters and particularly embryos that are smaller than four millimeters may be observed at a point where the heart will begin to contract but has not yet started to contract.

So the absence of a embryonic heartbeat in these circumstances is not definitive evidence of embryonic death.

So here we see a four millimeter embryo without a visible heartbeat.

And although I can assure you that overwhelmingly when you do a follow up sonogram in this group of patients, you will not find a heartbeat.

We always do follow up sonography in the anticipation that on a rare occasion we have identified an embryo whose heart has simply not started to beat at this point in gestation.

No Heartbeat in Visible Embryo

So we need to look at that group where there's no heartbeat.

Present embryos greater than five millimeters versus less than five millimeters.

Two thirds have embryos greater than five millimeters.

So if no heartbeat is present, that is a very poor prognostic sign.

In a third of the patients, the embryo is less than five millimeters.

Now many of these 51 cases are diagnosable as failed pregnancies.

These are all diagnosable as failed.

Many of these are diagnosable as failed.

Recall that we said that if we have reached a minimum menstrual age of greater than seven weeks or greater than six weeks, if you prefer perfectly safe number to use and there is no heartbeat, you can be confident that the pregnancy has failed.

And you can also be confident based on something that I call the expanded amnion sign, which we will discuss later in the lecture.

So if we look at our patients that have no heartbeat and an embryo greater than five millimeters, it is safe to evacuate that pregnancy.

I'm not saying that the pregnancy should be evacuated, but you can be confident that there is virtually no chance that you are evacuating a pregnancy that could go on to success.

So here we see a nine millimeter embryo with no heartbeat.

One may be highly confident that that pregnancy has failed.

However, what should we call it in our report?

What I can tell you is that doctors don't like to use the word dead.

I've never seen a report sent out where it says the embryo is dead.

There are a variety of terms that are used.

Strictly speaking, the term non-viable doesn't work because viable is defined as capable of living, especially said of a fetus that has reached the stage of development that it can live outside the uterus.

Obviously, no embryos are viable, therefore all early first trimester pregnancies are non-viable.

The good news, however, is that this term has been misused for so long.

It is now considered correct to use the term non-viable when indicating death.

So if we have an embryo that is less than five millimeters, this is our first group where we're going to recommend a follow up.

And I always recommend four days because knowing that the embryo was going to grow one millimeter a day in four days, we will have exceeded our five millimeter limit regardless of the size of embryo that we observed.

So here is that four millimeter embryo.

Again, without a heartbeat, I would simply recommend a follow-up sonogram in four days.

So if we look at our patients, there were 147 that had no heartbeat.

96 of those had embryo greater than five millimeters.

51 had an embryo less than five millimeters.

This is really our first group that we must recommend a follow up sonogram.

So if I saw this patient, four millimeter embryo, absent heartbeat, I would get a follow up sonogram provided that her minimum menstrual age is less than seven weeks.

No Visible Embryo or Fetus

Importantly, many abnormal gestations cease development before a recognizable embryo forms.

In our study, 23% of women who were threatening to abort did not have an identifiable embryo or fetus.

Here we see an aborted normal appearing early gestation.

You can appreciate all of these fronds of developing chorionic villi, the chorionic frondosum through the bare area of chorion, the chorionic laeve.

You can appreciate the yolk sac and the embryo lying immediately adjacent to it.

Just as we see on our sonograms, here's an abnormal sac, a so-called anembryonic pregnancy.

The sac is quite large.

Obviously we see no embryo within it, and indeed it's very difficult to find chorionic villi.

You have to look around to even find some villi.

In the classical sonographic distinction between normal and abnormal gestations that did not have an embryo.

It was the appearance of the chorion and decidua and the shape and position of the sac that were predominantly used.

Normal sacs are round, elliptical or crescentic.

They show the double sac sign.

The chorionic villi are nice and thick, always greater than two millimeters in thickness.

The chorionic villus amplitude is generally bright, usually as bright as the uterine bladder interface.

The wall of the sac is smooth and it is generally positioned high in the uterus.

Here we see a beautiful normal looking gestation sac.

Although we cannot find an embryo within it, we appreciate the double sac sign.

We appreciate a thick margin of developing chorion.

The chorionic tissue is bright, the sac is smooth and oval in shape, and it is positioned high in the uterus.

Minor Criteria for Abnormal Gestations

There are a variety of criteria, which I will call minor criteria based on abnormalities of those observations, either a absent double sac sign, inappropriately seen thickness of the margin of the sac, inappropriate amplitude of the margin of the sac irregularity and contour or low sac position.

These indeed have a rather high positive predictive value for a poor outcome.

But unfortunately in this area, a 95 or 96% positive predictive value is not a value to us.

It would be great if we were doing that with a diagnosis of pancreatic carcinoma, but we want to be as close to 100% as is possible when diagnosing early pregnancy failure.

So here we have a sac that actually shows many abnormal features.

It has abnormal shape.

We cannot identify a well-defined chorionic rim, so neither is it appropriately thick or appropriately bright.

If indeed we have more than two minor criteria, the positive predictive value increases to approach 100%.

So in this case, we have three minor criteria.

We may be virtually certain that this is a failed pregnancy.

Major Criterion: Mean Sac Diameter

The only major criterion that I use is based on the mean sac diameter.

And whether or not an embryo is identified in a transabdominal sonogram, a mean sac diameter of 25 millimeters, we should always be able to see an embryo with endovaginal sonography.

I use 16 millimeters mean sac diameter.

Now, there are many disputes just regarding the size that the sac should attain without embryonic visualization before one calls a failed pregnancy, and these numbers range from 16 to 20 millimeters.

What I'm trying to say to you today is choose a number that you can tolerate 16, 17, 18, 19, 20.

I don't care which number you use, but choose a number and that number should be used in an effective management.

We're now going to use a look at our flow chart again and look at embryos that are, I'm sorry.

We're going to look at circumstances where we do not identify the embryo.

We'll make that 100% of those instances, and we're going to identify a sac that is greater than 16 millimeters half the time, and a sac that is less than 16 millimeters half the time.

This is the second group in whom we should recommend a follow-up sonogram demonstrating a mean sac diameter less than 16 without an embryo being visualized.

Now again, many of these cases can be diagnosed as failed.

If the minimum menstrual age is greater than seven weeks, then you may again diagnose this as a failed pregnancy, and you can also diagnose it as a failed pregnancy.

If you observe the amnion sign, which we'll discuss later,

You can also diagnose it as a failed pregnancy.

If you see numerous minor criteria, let's look at some examples.

Here's a transabdominal sonogram, mean sac diameter, 28 millimeters, no visible embryo.

This should be and can confidently be diagnosed as a failed pregnancy.

Here we see a mean sac diameter of 25 millimeters on an endovaginal sonogram.

And again, we can confidently diagnose this as a failed pregnancy Notice as well, that in addition to our major criterion of our inability to see an embryo, there are also numerous minor criteria that are visible in these images.

Abnormal sac shape, abnormal margin, echogenicity, abnormal sac shape.

Let's return to the example I showed you a few moments ago here.

We're in that gray zone between 16 and 20 millimeters, mean sac diameter, but we have, again, multiple minor criteria.

So I would have no difficulty whatsoever diagnosing this as a failed pregnancy.

Same here, we're in that gray zone between 16 and 20 millimeters, mean sac diameter, but again, numerous minor criteria, abnormal shape, abnormal margin, thickness, abnormal margin echogenicity.

Similarly, here we have abnormal sac shape and abnormal appearance of the developing placenta.

Now the board of faculty of clinical radiology of the Royal College of Radiologists and the Council of the Royal College of Gynecologists in Great Britain Have diagnostic guidelines that state that no ultrasound diagnosis of early pregnancy failures should be made for sacs less than 20 millimeters at initial visit, at least one additional examination after a minimum of seven days has to be performed in order to establish the diagnosis.

And in cases of an empty sac, less than 15 millimeters in diameter, the guidelines require that a follow-up scan is scheduled two weeks later.

I have to say that I consider this an abdication of our diagnostic responsibility.

This is geared to the lowest common denominator of practitioner, the individual least likely in Great Britain, to make the proper observations to let this woman know that her pregnancy has already failed.

If we, again, go back to our algorithm and make this a hundred percent of the fetuses, now that we've done a sonogram, when a woman threatening to abort, there is no visible embryo or fetus and look at the relative size of the sac.

The sac is less than 16 millimeters and 50%, 15% fell between 16 and 20 millimeters, and 35% were greater than 20 millimeters.

Most of these cases will require a follow-up sonogram.

Some of these cases may require a follow-up sonogram.

Although identification of a sac less than 16 millimeters without an embryo is not definitive for pregnancy failure.

It is certainly a bad prognostic sign.

65% of these patients in Falco study went on to spontaneously abort.

And nearly all women, all women greater than 35 years of age in this group, go on to abort.

So again, age is a significant impact on this because chromosome anomalies are the leading reason for women to undergo first trimester pregnancy loss of the total of 600 patients, only 22 fell between 16 and 20 millimeters.

So if you choose to use 20 millimeters, fine, it actually impacts a relatively small number of women.

However, as I've said, in virtually every instance where the sac is greater than 16 millimeters, it is safe to evacuate the pregnancy without having any serious concern that you might have interrupted a pregnancy which would have gone on to be successful in those that are less than 16 millimeters.

The literature pretty much teaches us to look for a yolk sac.

Indeed, the yolk sac is more readily identified on a sonogram than is the embryo, and that is because it is the perfect target.

It is a membranous fluid containing sac inside of a fluid containing sac.

So whether we are using transabdominal or endovaginal sonography, we have a tremendously good opportunity to identify the yolk sac in a normally developing pregnancy.

Indeed, we often see yolk sacs in very small pregnancies.

In 1992, Kurtz was the first one that, that I'm aware of.

That said, failure to detect the yolk sac is not a reliable indicator of pregnancy failure.

I concur with this and I no longer use this as a significant indicator of pregnancy failure.

Here we have a patient with a mean sac diameter of 11 millimeters.

Ordinarily we would very easily identify a yolk sac within this size of pregnancy.

We did not.

But this patient goes on to have develop a normal looking pregnancy with a living embryo.

Special Signs for Diagnosing Failed Pregnancy

I'd like to now turn to two very useful signs that have helped me to sort out many of these more complicated cases.

The one I call the amnion sign.

What it means is that visualization of the amnion, concomitant embryonic visualization confirms pregnancy failure.

Basically, we're looking at a nine millimeter embryo here, and that is the typical size embryo where we first begin to identify the amnion because a little bit of fluid starts to creep into the amniotic cavity, making the membranous amnion visible.

Notice that you cannot see the entirety of the amnion, but you can see it here.

We have just a seven millimeter embryo, but we're just beginning to be able to identify a little reflection from the amnion.

Not a complete amnion, but just a little reflection.

So it is my opinion that basically you cannot see any of the amnion before the embryo reaches seven millimeters crown rump length.

You never see the entire amnion until the embryo is well past 10 millimeters crown rump length.

So these are two examples of the amnion sign.

We have our yolk sac, we have our amnion, but we are unable to identify an embryo within the amniotic sac.

This, however, is a sac greater than 16 millimeters.

So we would just say that inability to identify the embryo under any circumstance would be a bad prognostic sign and diagnostic of pregnancy failure.

Notice as well that the margins of the sac are abnormal.

There are many, many findings that this is a failed pregnancy, but here is a much smaller sac where we see the yolk sac and we see the amnion in its entirety, but there is no embryo within it.

This is a sac that is significantly smaller than 16 millimeters.

But in addition to this definitive finding, we also see that the margin of the sac and its shape is quite abnormal.

Although the sac is less than 16 millimeters in mean sac diameter, one can confidently diagnose this as a failed pregnancy.

It is worth looking for the amnion sign.

Here we have a sac smaller than 16 millimeters.

We identify the yolk sac, and looking around we can see that in fact there's quite a large amniotic sac at this time.

Also, multiple minor criteria, abnormal sac margin, abnormal sac shape, abnormal margin echogenicity.

Although the sac is less than 16 millimeters, one can confidently diagnose this as a failed pregnancy without any concern that we might interrupt a potentially viable product.

Expanded Amnion Sign

The expanded amnion sign I use to help identify embryos that have died but indeed are smaller than five millimeters in crown rump length.

Now this embryo is actually larger than five millimeters, but here we have an embryo significantly smaller than five millimeters, but we can see a large portion of the amnion in this case.

In that instance, the diagnosis of pregnancy failure is entirely possible and accurate.

Here we have another example of an embryo smaller than five millimeters, but we can see virtually the entire amnion that embryo should be greater than 10 millimeters in size, and it should have an easily visible heartbeat.

So again, the expanded amnion sign is worth looking for.

We have a little yolk sac here.

We have a very tiny little embryo.

Ordinarily we would be reluctant to make a diagnosis of pregnancy failure and ask for a follow-up sonogram.

But if you look and identify that the amnion is indeed visible, and in fact the amniotic cavity is quite large, you can be quite certain that this patient has a failed pregnancy.

And similarly here, this embryo is smaller than five millimeters, but the amnion is entirely visible.

That can't be a normal pregnancy.

Follow-up Sonogram Recommendations

So in the group of patients who are threatening to abort, who really requires follow-up sonograms, well, we've said that patients that have an embryo less than five millimeters without a heartbeat, typically patients whose mean sac diameter is less than 16 millimeters.

When we don't identify an embryo, typically we would do that.

Some cases in this 22 between 16 and 20 millimeters might require a follow up depending on your own level of confidence and appropriateness for required follow-up examination.

That means that at the very most, somewhere between 122 and 142 of the 600 patients require a follow-up sonogram.

So at most 20 to 24% of threatened abortions need a follow-up sonogram.

And many of these can be unequivocally diagnosed as failed pregnancies using some of the techniques that I have mentioned to you.

Terminology for Failed Pregnancies

So if we think it's a failed pregnancy, what is the term that we should use?

Well, blighted ovum is a term that means a fertilized ovum in which development has become arrested, and that's a perfectly legitimate term, but we never use it anymore because it is politically incorrect.

The feminist movement wants us to call these blighted sperms instead of blighted ova.

The correct term is early pregnancy failure, which is an early gestation containing a dead embryo or lacking an embryo.

And that covers all circumstances that you will encounter.

However, I do use the phrase embryonic demise or fetal demise as appropriate.

When I do observe an embryo or a fetus, that lacks a heartbeat.

Thank you very much.