Pitfalls: Female Pelvis, Part 1

Introduction

My task for this course was to discuss pitfalls and imaging the female pelvis.

I decided to bring this down into two components.

In my first talk, I'll be talking about some issues in the pregnant patient, and then in my second talk this afternoon, I'll be talking about the non-pregnant patient.

I have no financial disclosures for either of these talks.

Learning Objectives

What I'd like to do for the learning objectives for my first lecture are to concentrate somewhat on first trimester pregnancy failure and how to diagnose this on ultrasound because there have been some recently revised guidelines here that I think everybody needs to be aware of.

I will be discussing the diagnosis and management of pregnancy of unknown location, otherwise known as the PUL and also intrauterine pregnancy of uncertain viability or PUV.

I'm going to spend the majority of this talk talking about ectopic pregnancy because I think this is a very important topic and there are many pitfalls that I think we can fall into here if we're not aware of them.

I'll be concentrating on sort of the more typical tubal ectopic and then spending some time talking about some of the more unusual sites of pregnancy implantation.

If I have time at the end, I will also touch briefly on placental implantation disorders.

Normal First Trimester Pregnancy Transvaginal Ultrasound Milestones

What I'd like to do first is just review the normal first trimester pregnancy transvaginal ultrasound milestones.

The first structure that we expect to see in the uterus is the gestational sac.

And typically we'll see this at a gestational age of about four and a half to five weeks.

Once we identify it, we can use the mean sac diameter to assign gestational age, and we expect to see this when the beta level is either a thousand or 2000 depending upon which reference your particular lab uses.

And that has been referred to as the discriminatory level, or it's the beta level above which we expect to reliably see a gestational sac.

And I'm going to discuss some more recent updated information regarding this discriminatory level in just a moment.

And it is important if we can identify a gestational sac within the uterus, because if a woman comes in in the ER and she's got a positive beta and she's bleeding, she's having pain, if we can identify a sac in the uterus, then that is going to make the likelihood of an ectopic very, very low.

It's not zero as I will discuss, but it is very low.

Identifying a True Gestational Sac

So there've been a couple of signs that have been described to help us to identify whether or not a fluid collection that we're looking at in the uterus is in fact a true gestational sac and not some other fluid collection.

And one of these signs is demonstrated here.

This is the intertidal sign.

And what this is is that you see a well circumscribed oval or round in shape cystic structure, which has an echogenic rim, and it is located eccentrically within the endometrium.

And this is just a cine clip to show you here in real time what this looks like.

And if you see this, it does not diagnose a hundred percent the presence of an intrauterine pregnancy, but it is very suggestive and you should recommend follow up.

Of course, we cannot determine that the pregnancy is viable until we see fetal cardiac activity, but if you see these features, you can say, I do see this, and I think it could be a very early IUP.

Now what about this case here?

So is there a gestational sac present?

And I run into this, I would say, not all that.

And frequently where I'm presented with images and we see that there is thickening here of the endometrium, but I don't see a gestational sac within it.

And that's sort of problematic because the patient's got a positive beta.

So where is this pregnancy located?

So I go back in and I re-scan, and now I do in fact just moments later, identify this little intertidal sign.

And the difference here is that I used a higher frequency transducer.

And so I really want to encourage you in these first trimester pregnancies where we're looking for these very small structures, use meticulous technique and always try to use the highest of resolution imaging that you possibly can.

Now, the other sign that's been described as the double decidual sac sign, and this refers to the two layers of the decidua, which appear as echogenic rings around the chorionic or gestational sac.

Generally though, you won't see this sign until the sac is greater than 10 millimeters for the mean sac diameter.

And usually by then we'll also identify a yolk sac.

So to be honest, this particular finding is usually not all that helpful, but seeing a yolk sac is very helpful because once we identify a yolk sac, then yes, we know this is indeed a true gestational sac.

It may not still be viable, but at least we can say, well, again, an ectopic gestation is very, very unlikely here.

The final structure that we'll see here is the embryo or fetal pole.

And nowadays we can actually visualize this before we see a fetal heartbeat.

And of course, once we identify it, then we can use the crown rump length to assign a gestational age.

Fetal Cardiac Activity

Few words about cardiac activity.

Again, we need to see cardiac activity to say that the pregnancy is viable.

And the value that we have been using for many years now is that once you reach a crown rump length of five millimeters, you should expect to see on a good quality transvaginal scan fetal cardiac activity.

However, I'm going to be again, discussing some new information a little bit later saying that maybe this five millimeters is just a little bit too low and we need to bump that up a little bit.

Pregnancy of Unknown Location (PUL)

So if a patient comes into the ER complaining of vaginal bleeding, she's got a positive beta, and oftentimes we don't know what the quantitative level is and we see a normal central echo, IE we do not see any signs of an intrauterine pregnancy, but we also don't see any signs of an ectopic.

This is basically the situation where we're gonna have three things in our differential.

Maybe this is a very early intrauterine pregnancy that's just too early, we can't see it yet.

Maybe she was pregnant, but she's bleeding and she's passed the pregnancy.

It's a completed abortion.

But of course the diagnosis we don't want to miss here is an ectopic pregnancy.

And this is the situation which we refer to as a pregnancy of unknown location or PUL.

She's got a positive beta, but we cannot identify where it is located.

We can't see it in the uterus, or we can't see it outside of the uterus.

And really, in terms of managing these patients, it comes down to balancing the risk of missing ectopic.

And also on the other hand, incorrectly managing an early IUP, which could go on to be a normal pregnancy, but may end up with an inadvertent termination if the woman is given an embryo toxic drug such as methotrexate.

So basically in these patients, if they're stable and there's no evidence for an ectopic, we want to suggest that they be followed very closely with serial beta levels as well as follow-up ultrasound.

Now this is a paper that was put out by the group at the Brigham and, and this group, Dr. Benson and Dube and their colleagues, they've done a lot of work in the last year or two looking at some of these first trimester parameters.

And what they found was that in a series of patients in early pregnancy in their practice, they had several cases where even with the beta as high as 4,000 and no IUP visible on the initial scan, those women still went on to have normally developed pregnancies.

And you can think about this, some of the issues might be, well, what was the technical quality of the scan?

Did maybe the patient have fibroids, which was making it difficult to identify an early sac?

Could this be a twin gestation?

For a given gestational age, what we're going to see in the uterus for a twin gestation is not going to be the same for a given beta level that it would be for a singleton pregnancy.

So, their group, they've really done a lot of work and have really brought to our attention now that, as they state in their next paper here, we do first do not want to do any harm to early pregnancies.

And so we always, if it's a pregnancy that's desired and the woman is stable, we wanna give it sort of the benefit of the doubt and just follow these patients closely.

And in fact, they sort of state that if you have any intrauterine fluid collection, absent any signs of an ectopic, that woman is much more likely to go on to develop an intrauterine pregnancy.

Because the incidence of a pseudo gestational sac, which is usually the main differential we're thinking about in the setting of ectopic, is actually very, very low.

Absent other findings, and I'll be presenting some more data on that in just a moment.

Diagnosis of First Trimester Pregnancy Failure

So these are the criteria that have been out there for many, many years in terms of what we can see in first trimester pregnancy that is predictive or associated with a poor outcome, a fetal heart rate or a fetal cardiac activity, not seen with a crown rump length greater than five millimeters, or a reliable gestational age of six to six and a half weeks, a mean sac diameter greater than eight millimeters with no yolk sac and greater than 16 millimeters and no embryo.

And these are actually guidelines that put out by the ACR.

And if we have a beta level that's greater than a thousand, and we do not see an intrauterine gestational sac.

But again, these have been recently revised and there's a growing body of literature sort of looking at these current guidelines.

And I've just quoted one paper for you here and there's more information in your handout, which I can't present here, which have actually sort of demonstrated that these current guidelines are actually somewhat dangerous and may lead to inadvertent termination of what could be a normal pregnancy.

And actually based on their results in this multicenter study, this group advocates a threshold value of 25 millimeters for mean sac diameter and no visualization of an embryo and a crown rump length of seven millimeters.

And no fetal cardiac activity in order to be confident in diagnosing a first trimester pregnancy failure with a false positive rate that's zero.

So, in order to address this issue, the Society of Radiologists in Ultrasound had a consensus meeting at their annual meeting last fall.

And every year they sort of choose a different topic.

And last year they decided to focus on early first trimester diagnostic criteria for non-viable pregnancy.

And these were the guidelines that they established and they should be coming out in publication fairly soon.

And so they advocate that if the crown rump length is greater than or equal to seven millimeters and there's no heartbeat on a transvaginal scan that is definitive for a failed pregnancy, if it is less than seven millimeters and there's no heartbeat, that's going to be suspicious but not definitive.

If you have a mean sac diameter that's greater than 25 or equal to 25 millimeters and no embryo, then that is definitive for failed pregnancy.

If on the other hand, it measures from 16 to 24 millimeters, again, that's suspicious but not definitive, and those patients need to be closely followed.

If you have a pregnancy of unknown location and the beta is less than 3000, we should not be advocating treatments such as methotrexate or DNC, because if we do that, we may actually interrupt what could be a viable IUP.

So they, again, in this particular set of guidelines, they suggest that actually you wanna see a beta that's above 3000 before you really begin to be concerned that there's not going to be a viable pregnancy.

Ectopic Pregnancy

All right. So with that as a little bit of background, I'd like to leap into the topic of ectopic pregnancy for the majority of the remainder of my talk because this is a very important topic, as we all know.

It accounts for 6% of all pregnancy related deaths, and it is the leading cause of first trimester maternal death.

And I think there are a number of pitfalls that we need to be aware of in which I have come to learn about in my years of practice here.

So there, we're seeing an increased incidence of ectopic pregnancies, in large part to the increasing prevalence of the different risk factors associated with ectopic.

And note how I've listed a prior C-section as a risk factor because a c-section implantation or C-section scar implantation is indeed considered a form of ectopic.

Now, most ectopics will occur in the fallopian tube and the ampullary portion of the tube is where most of these ectopics will occur.

But we know that there are some less common types of pregnancy implantation, which can be somewhat problematic to not to diagnose sometimes, and I'll be reviewing those.

So the diagnosis of an ectopic pregnancy is generally based on a combination of looking at both the hormone levels as well as ultrasound.

I've already talked about the discriminatory threshold level of a beta above which we expect to see an IUP.

Again, I think we've bumped that up a little bit now to at least 3000.

But if you've got a beta that's 5,000 and you don't see an IUP, again, you have to worry that you could be dealing with an ectopic.

But again, I wanna urge caution.

It's very hard to be definitive when we only have one single isolated beta HCG value.

More than 50% of patients with an ectopic will have a beta that's low, that's less than 2000.

And that's because we don't see a normal doubling time of a beta in an ectopic as we do in a normal pregnancy.

And so it's good to keep that in mind because even with a fairly low beta, and we'll see some examples, we can identify an ectopic pregnancy at ultrasound.

Our approach is that we evaluate all of these patients with both a transabdominal and a transvaginal scan.

The transabdominal scan gives you a global evaluation of the pelvis.

It's got a larger field of view than the transvaginal scan, and I find it very useful to look for fluid in the upper quadrants.

But pretty much in every instance, we're gonna go on to a transvaginal scan because that's going to allow us to see these early structures of pregnancy with better detail, and also we can better characterize any adnexal masses.

Pitfalls in Diagnosing Ectopic Pregnancy

So one pitfall, and I'll be having a bunch of these little different hazard warning signs here as we go along to indicate these pitfalls.

So one pitfall is you don't wanna mistake a pseudo sac related to an ectopic for a gestational sac and vice versa.

You don't wanna conclude that a gestational sac is just a pseudo sac.

So I've already alluded to this, and again, this study comes out of the Brigham where they found in a series of patients that actually only 16 to 17% or so of their ectopic pregnancies in this series actually were associated with a pseudo sac.

Some of the clues here are that unlike the true intrauterine gestational sac, this is not eccentric, it's centrally located within the uterine cavity because what it is, it's usually blood that's accumulated within the endometrial cavity.

They tend to have sort of a more pointy edge here.

They're not round, they can change shape during the time when you are imaging them.

And also it's not simple anechoic fluid in here, it's echogenic because it represents blood products.

And here's another example of a pseudo sac down here.

On the other hand, you know, if you see a collection that's smooth walled anechoic, it's located in the decidua and you see no adnexal mass, the probability of an ectopic in that scenario is very, very low on the order of less than 1%.

And what I'm showing you in this example here is just to show you how differently these look.

So this is a woman who does indeed have a nice little intertidal sac here, but she came in with vaginal bleeding, which probably some implantation bleeding.

Sometimes we see bleeding in the setting of a normal first trimester pregnancy, and now you can see the blood that has accumulated within the endometrial cavity, which is what sort of a pseudo sac might look like.

And so you can see how these two look different on ultrasound.

We're always going to look for complex fluid or fluid and note whether or not it's complex.

Because if you see complex fluid, then that means that there's blood.

Now there is a differential.

Yes you can have a ruptured corpus luteum with hemoperitoneum in an IUP just as you can with an ectopic.

But here's where I think obviously the clinical status of the patient as well as how much fluid we're dealing with can be very helpful.

Also, I think it's very useful if you do see fluid, take a good look in that fluid because when you do that in this particular patient, you see this tiny little tubal ring.

So oftentimes you will be able to identify the ectopic pregnancy in the area of the abnormal fluid.

Another pitfall I'd like to sort of remind you of is that many times the clot in the pelvis actually becomes more isoechoic and it can be hard to recognize, it can be isoechoic to the uterus.

It can sort of blend in with the surrounding structures such as the bowel gas.

So again, I think that's another reason why in all of these ectopics, or potential ectopics, I always look up in the upper abdomen.

Generally the fluid, blood up in the upper abdomen is more anechoic.

And also our clinicians wanna know if I see fluid in the pelvis, is it complex?

Number one, does it look like blood?

And also do I see any in the upper abdomen?

Because if you see fluid in Morrison's pouch, then that means that there's at least 500 ccs of blood present.

And again, that might help in terms of how this patient should best be managed.

Now this was a case that was given to me by a colleague, so I'm not sure exactly of all of the details of how this unfolded, but this was a woman who came into the ER complaining of abdominal pain and the CT scan was done.

She got oral but no IV contrast because she had a contrast allergy.

And what was seen was that there is this high attenuation fluid, namely blood, which is down here in the cul-de-sac of the pelvis.

And then it looked like there was this cystic structure here in the left adnexa.

So you know, if you're coming across this, oh, this is most likely a ruptured hemorrhagic corpus luteum.

You know, we see these all the time.

It's not unusual for these patients to present with abdominal and pelvic pain, but and again, I'm not sure exactly how this happened, but after this CAT scan was done, this patient was actually found to be beta positive.

And that's going to totally change your concern here from just a ruptured hemorrhagic ovarian cyst or corpus luteum to a ruptured ectopic.

And actually she did go to the OR and this was a ruptured ectopic that was confirmed at surgery.

So the pitfall I wanna remind you about here and caution you about is that in any female patient of reproductive age who presents with pelvic pain or vaginal bleeding, you have to exclude the possibility that she's pregnant and that you could be dealing with an ectopic pregnancy.

This is another case that actually just came through our practice about a month ago.

This 38-year-old outpatient woman presented with abnormal vaginal bleeding, and her gynecologist referred her to an MR at our hospital because she was concerned that perhaps this patient had fibroids.

And so the MR was done.

And what we saw was that there is a normal ovary here.

And then it was noted that there was this cystic mass here in the right adnexa, which appeared to be separate from the right ovary.

And we can see on the post contrast images that it's a rim enhancing here.

So the person who reviewed this, you know, said, okay, there's a right adnexal mass, it's not related to the ovary.

I'm not sure exactly what the etiology is here.

Maybe this is related to the tube, maybe it's some bowel related pathology.

So from here, she actually went on to a contrast enhanced CT scan.

And here we see again the right ovary where we see a little enhancing corpus luteum.

We see this rim enhancing cystic structure, which was separate from the ovary.

Again, it was not clear what the etiology of this abnormality was, and at this point, the patient was referred for an ultrasound.

Remember this was an outpatient, and she had the ultrasound done at in the doctor's office.

And actually this proved to be an ectopic pregnancy at about eight weeks gestation.

And so I think that, you know, when the patient comes in and is an outpatient, and she's referred for an MR to rule out fibroids, you know, we do have a process where we have the patient, they have to be interviewed, we ask them could they be pregnant?

If they say no, then we do not mandate testing.

If they're not sure, if they're not sure of their LMP, then we do require them to be tested to make sure she's not pregnant.

This woman sort of looking back at this told both for the CT scan and the MR, there was no way that she could be pregnant.

So I think that, you know, even if you think that the patient is not pregnant, if you see something that looks very suspicious for an ectopic, just get on the phone and call the clinician and say, you know, maybe this woman needs to be ruled out that she could potentially have an ectopic.

Tubal Ectopic Findings and Pitfalls

Now, in terms of findings of ectopics in the tube, you know, of course this is the easiest situation where we see this live embryo here out in the adnexa, separate from the uterus.

But I wanna caution you again, you know, if you're presented with an image like this, and this was a living pregnancy at about eight and a half weeks, okay, so it looks like a nice little normal embryo here.

There was fetal cardiac activity, but where is this pregnancy located?

And I'm really not giving you the sort of landmarks here so that you can know for sure where it is.

And actually as you look further, this is outside of the uterus.

Here's a uterus over here, and this was a tubal ectopic.

And so you have to be very, very careful.

And I don't know about you, but in my practice we're reading more and more offsite ultrasound.

It just seems to be something that we can't avoid these days.

And so just make sure that, you know, sometimes you know such a limited field of view and you're focusing on the pregnancy, you just wanna make sure that it is indeed within the uterus.

So don't mistake an ectopic pregnancy for an intrauterine pregnancy.

You wanna confirm that a pregnancy is intrauterine by scanning the entire uterus from all the way down in the cervix, all the way up to the extreme fundal region of the uterus, including both cornual tubal regions.

We'll see these as a frequent manifestation of an ectopic in the tube.

Again, this is the trophoblastic tissue that when you cut across it in cross-section, it looks like this ring here, it is separate from the ovary.

And these can be a little bit tricky.

Here we see on the cine clip, most of the time you'll see this situated somewhere between the uterus as we have here and the normal right ovary.

So here's this tubal ring right here.

Now this was a case where a small tubal ring was initially overlooked, sonographer did the case, brought in the images and said there was no IUP, but there was no ectopic.

And so we were kind of ready to put her into a PUL sort of algorithm and follow up.

But when we went back in and re-scanned this woman and just put a little pressure with the transvaginal probe and also with your non scanning hand, put a little pressure on the patient's abdomen, what we were able to do was kind of move away some of the structures in the adnexa, including these loops of bowel here, and identify this very tiny little tubal ring.

Now, if we hadn't seen this, of course we would've recommended very close follow up for this woman.

But, you know, being able to make this diagnosis, she could be taken care of right away.

She was given systemic methotrexate and she did well.

So again, use that sort of dynamic maneuver, especially when you're looking for these very small ectopics.

Now, you also don't wanna mistake a tubal ectopic for a corpus luteum, and the doppler characteristics are very similar.

Both of these are going to demonstrate the so-called ring of fire appearance.

So that doesn't really help you all that much.

Really what's can be very helpful is the echo texture.

Most tubal rings will be very echogenic with respect to the ovary.

On the other hand, most corpus lutea, the rim will be either isoechoic or hypoechoic with respect to the ovary.

So that can be a very helpful feature.

But I think what really is most important is that you wanna demonstrate, you know, see whether the structure that you think, is it a corpus luteum, is it a tubal ring?

Well, is it in the ovary or is it outside the ovary?

And sometimes when a corpus luteum is exophytic, it can be a little bit problematic and a little bit of a challenge.

And so again, I'm using this sort of gentle pressure here.

Some people refer to this as a sliding organ sign.

So here we have an ovary with a corpus luteum within it, and then we have this small little tubal ring here, which was separate from the ovary and that became much more obvious sort of doing that sort of real time maneuver.

Okay, this woman comes in with a beta, it's pretty low, it's 154, and she's in the ER and she's got right adnexal pain.

Now she had an enlarged fibroid uterus.

And I'm showing you just one transvaginal image to show you that there was no pregnancy identified with the uterus here.

She did have some, she had even larger ones up here in the fundus.

It was difficult to see the right adnexa, you know, maybe right ovary was down here.

She was having right sided pain.

So what are you gonna do here?

Are you gonna say, okay, I'm done with my study.

I'm basically gonna say I don't see the pregnancy.

She needs to be closely followed.

Well, again, I really wanna encourage you in all these cases, don't just look at a transvaginal scan, went back in and re-scanned this woman transabdominally.

You don't even need a full urinary bladder.

And when we did that, what we saw was here was the uterine fundus over here.

Now we're seeing that right ovary much better than we could transvaginally.

And here now is our little tubal ring right here.

And we could really only see this tubal ring when we evaluated this patient transabdominally.

So if you have an enlarged uterus, you know, from fibroids or some other process, you wanna make sure if you can't see the ovary well, it's probably likely that you're not gonna be able to see an ectopic very well either.

So another I think very important pitfall is that you, I can guarantee you are going to miss an ectopic pregnancy if you only evaluate these patients transvaginally, and you do not include a transabdominal scan in your imaging protocol.

Case in point, this woman was referred to us for an MR, she had had ultrasound assessments elsewhere, and what had happened was she was pregnant, she was bleeding, they thought she passed the pregnancy, she came in for repeat ultrasound because her beta was still going up.

They noticed that the uterus looked kind of unusual and abnormal, and they were actually concerned, perhaps her beta's going up because she has an invasive mole.

So it was in that context that they sent her to us for the MR.

And you can see that the uterus is abnormal here.

There's nothing in the cavity, there's no pregnancy, but it is abnormal in that the junctional zone is markedly thickened.

There's these little areas of cystic change.

So what are we dealing with here if this patient is non-pregnant?

Well, of course this looks like a uterus that has adenomyosis.

And so, okay, we didn't see anything that looked like a mole.

So we went out and we looked in the adnexa, and what we found here was this cystic mass over here.

And it was at the level, it was pretty high, it was at the level of the iliac crest.

And if you look very closely, you can actually see a cranium there.

And sure enough, this went to surgery and this was an ectopic in the left lower quadrant.

And I think, you know, in sort of finding out sort of how this whole unfolded, again, at this particular site where the patient was imaged, they only do transvaginal scans.

They don't do transabdominal scans.

And so I think that this was just too high in the left lower quadrant and they couldn't see it.

And then the question was, and we kind of postulated that maybe the uterus looked a little bit bizarre was that, you know, think about it, adenomyosis is when you have ectopic endometrial glands and stroma.

And so if you've got the hormones related to the pregnancy, we probably were seeing some decidualization going on in these ectopic glands, which was just creating sort of a difficult and unusual ultrasound appearance of the uterus.

So of course this was, you know, Friday afternoon at five 30, we had to call the clinician.

The clinician had to track the patient down because this was done as an outpatient.

Unfortunately, she came back and this was taken care of before any major disaster occurred, which it certainly could have if this thing went on to rupture.

Less Typical Sites of Ectopic Pregnancy

Moving on to some of the less typical sites of pregnancy implantation.

There's the interstitial ectopic, this is the preferred term rather than cornual ectopic.

And what this is, is when you have a pregnancy that implants in the intramural or interstitial portion of the fallopian tube, this is about two to 5% of ectopic pregnancies.

I would say we see a couple of these every year.

And the problem is, is that because it's the intramural portion of the tube, the pregnancy can be partially surrounded by myometrium.

So these pregnancies ectopics can present later and can sort of cause life-threatening hemorrhage when they do, if they rupture.

And the way you're gonna find see these on ultrasound is that you're going to note that the gestational sac is very eccentric.

And this is a pretty obvious case here, but you can see that the ectopic is sort of forming like a bulge at the edge of the uterine contour.

We don't see anything inside of the uterus.

Sometimes there's no myometrial mantle.

Sometimes you see a partial myometrial mantle.

And here's what this looked like at laparoscopy.

You can see all of the prominent blood vessels here.

The interstitial line sign has been described as a finding.

This was described many, many years ago now, where basically the line is just the endometrium which points to the pregnancy, which is located up in the interstitial region.

So here's another case for you.

This 23-year-old woman with first trimester pregnancy and pelvic pain was referred to us from the emergency room on the transvaginal scan.

It looked like the uterus was pretty normal, it was certainly empty.

The endometrium was not thickened.

And we saw both ovaries, they also looked normal.

There was no adnexal mass.

So anything else anybody would like to see transabdominal, right?

Okay, so went back in and I scanned her transabdominally.

And when I did that, I saw this and this, hmm, there's a little echogenic round thing here.

Again, sort of a bulging the fundus here.

And so I went back in and I re-scanned her transvaginally.

And actually this was an interstitial ectopic.

And so you can see the little sac here, again, sort of out in the cornual region here, completely separate from the endometrial cavity.

And I think the pitfall here was that the sonographer had just not scanned all the way up to the extreme fundus and out towards both cornua to make sure that there wasn't a sac there.

Now I think, you know, we do 3D ultrasound in the setting where we have an implantation and we're not quite sure where it is.

It's eccentric, you know, but am I dealing with maybe a transient contraction or am I dealing with a fibroid?

That's kind of displacing things.

And I think 3D can be very helpful for you in that setting.

And so here we see that the endometrium is indeed empty.

Here's our interstitial line sign.

And now here is our interstitial ectopic.

So it's pretty straightforward diagnosis, I think looking at this on the 3D.

So, but a pitfall here also is that you don't want to diagnose a pregnancy in an anomalous uterus and mistake that for an ectopic, namely an interstitial ectopic.

So, you know, if you look at this pregnancy here, here we have this gestational sac, and yes, it is eccentrically located over on the left here, but a couple of differences here compared to the interstitial ectopic, it is in continuity.

It touches the endometrium here, and it also is completely surrounded by myometrium.

So the feeling was that this was most likely not an interstitial ectopic, but she went for an MR.

And I think MR can also be a helpful problem solver, and I'll show you some other cases later in the talk as well.

And so what this was, was that this was a pregnancy that was eccentric because it was in the left side of an incomplete septate uterus, but it was completely surrounded by myometrium.

And so this was not an interstitial.

Now she's gonna have all the problems associated with the septate uterus and high risk of spontaneous pregnancy loss, et cetera.

But at least we can say that this is not an interstitial ectopic.

Again, here's a patient who came in in first trimester.

She had an early sac that was, again, very eccentrically located.

And you can see on the 3D that, but it is in the decidualized endometrium.

There is a complete rim of myometrium, and this was just a pregnancy in the left side of a complete septate uterus.

Cervical ectopics.

These are pretty uncommon. Again, I'd say we see maybe one or two of these every year or so.

And this is where you have the sac that implants within the cervix.

And you know, what you're going to see is that the sac is down in the cervix.

If you put on some color doppler, you may be able to actually demonstrate some trophoblastic type flow around it.

And also you wanna look to see if there's fetal cardiac activity, because really the main differential for this is, is this just a pregnancy that was in the uterus, but now it's on the way out and she's basically having a pregnancy loss in progress.

And it would be very unusual for the pregnancy to have progressed down to the level of the cervix and for there still to be fetal cardiac activity.

So that's one thing that can help you.

And so in this patient who was having a spontaneous abortion as we sort of scanned her, you can see a couple of differences.

Number one, there was no fetal pole with fetal cardiac activity.

Also note the shape of this sac here, it's oblong, it's irregular, and it also changed configuration and morphology as we were scanning this patient.

So if you're not sure on the first scan, just certainly recommend very close short interval follow up.

Now, as I mentioned, having had a c-section is now considered a risk factor for an ectopic because what can happen here is that, in this non-pregnant patient who's had a C-section, I just wanna show you that oftentimes at the hysterotomy site, it does not completely heal over and you get this little niche or space into which the gestational sac can implant.

And this is considered a form of ectopic because it is not completely surrounded by myometrium.

And so there's gonna be a high risk for rupture here.

And the keys to the diagnosis at ultrasound are that you're going to see the sac, it's got a low implantation, but it's not in the cervix, it's at the level of the uterine isthmus, which is sort of at the level of the internal cervical os.

And traditionally that's where we would expect to see the hysterectomy.

The scar related to a C-section also, depending upon how advanced it is, you can see here that sometimes the sac will not be round but will have a triangular shape because it's sort of partially located within that scar.

And so it sort of creates that shape of the sac.

And, you know, when the data was looked at from 2011, actually the C-section rate in the US is almost a third of all pregnancies delivered by C-section.

So again, this is, if you look at the OB gyn literature, there's almost sort of an epidemic of the C-section scar ectopics.

And again, it has to do with the fact that we're seeing so many patients who are undergoing C-sections, they want to avoid doing a DNC in these patients because there will be a high risk for uterine perforation.

And if there's no fetal cardiac activity, they may just treat these patients with systemic methotrexate, hope that it will involute, follow them closely.

If there is fetal cardiac activity, they will get injected with local KCL or methotrexate in combination with systemic therapy.

And again, follow them. All right?

Abdominal ectopic, pretty rare.

And I think the pitfall here, you know, is that if you've got a pregnancy that is somewhat advanced, as I've already alluded to, it can actually be very difficult to decide is this pregnancy in or outside the uterus?

So here's a woman who comes in and she was scanned at an outside facility prior to a pregnancy termination, and they were concerned about an ectopic.

So they sent her over to us.

And if I just showed you this image here, you'd say, oh, okay, this looks like about 11 to 12 week gestation.

There was fetal cardiac activity on real time scanning.

But again, be very, very careful because when you look further, here's the pregnancy here and it's actually sitting outside of the uterus.

It was sort of in contact with the anterior surface of the uterus.

Now, our MFMs were concerned that maybe because, you know, they would've expected a tubal ectopic to have ruptured by that point, given the large size of this.

So they were concerned maybe this is an implantation in the horn of an anomalous uterus, maybe like a rudimentary horn in a unicornuate.

So they asked us to do the MR just to make sure that the uterus was normal.

And indeed it was, here's the cavity, which looks normal, there's no pregnancy within it.

And here's the pregnancy sitting right here.

And the way they treated this was that they injected with KCL, they gave her systemic methotrexate, they admitted her, followed her closely, they did not want to go in immediately because they were concerned if they took her to surgery, there would be so much vascularity here and that this was adherent to the uterus that she may end up with a hysterectomy.

And she was a young woman and whatnot.

So they actually did sort of a two staged treatment plan here for her.

Here on the other hand is a patient with a second trimester pregnancy, once again in a septate uterus.

And you know, on ultrasound it could be tricky because you're gonna see what looks like an empty endometrium here.

But the difference here is that we do see a complete rim of uterus around this.

And also the gestational sac is in contact with the internal cervical os.

So again, I think MR can be a very helpful problem solver if you're not clear on where the pregnancy is located.

Heterotopic Pregnancies

Now, heterotopic pregnancies, these are very rare.

This is when you have a coexisting intra and extrauterine gestation.

These do occur in higher frequency after assisted reproduction, but you can also see these just sort of spontaneously occurring.

And I think one tip off is that, you know, we don't always have the quant beta available to us, but if you do have the quantitative level, you always wanna try to relate what you're seeing on ultrasound with what the beta level is.

And if you're seeing a beta level that's too high for what you're seeing on ultrasound, think about the possibility of a heterotopic.

This was a woman in the first trimester who had about an eight week IUP.

This was in the uterus, but she had fluid down in the cul-de-sac.

And if you look in that fluid, again, looking at the fluid very carefully, there were two yolk sacs, two fetal poles, and this was actually a heterotopic pregnancy with a twin gestation in the cul-de-sac.

And so, you know, I think another pitfall I'd like to sort of remind you of is that even though as I said earlier, if you see an intrauterine pregnancy, the possibility of an ectopic is very low.

It is not zero. So you certainly, even though you see the IUP, you do still wanna assess the adnexa.

Placental Implantation Abnormalities

Okay, so in the last five minutes that I have, then I do wanna just say a few words about placental implantation abnormalities, because again, these are becoming much more common and it goes back to the increasing frequency of cesarean sections.

And what this is, is when you have abnormal adherence of the placenta to the uterine wall, and there are varying degrees of invasion by the chorionic villi.

And there has been a reported tenfold increase in the incidence of these disorders over the past 50 years.

They occur in about one in 2,500 deliveries.

And the primary risk factors are, number one, having a low placenta, i.e. placenta previa, and also having had prior uterine surgery where there's a scar and a defect in the myometrium.

And the most common surgery is going to be the C-section, although you can also see this in patients who have had other surgeries, maybe a myomectomy for fibroids or maybe she had a resection of a septum in a septate uterus.

So there are some other causes and actually in up to 7% there may be no identifiable risk factors at all.

Now this is a continuum and a lot of people use the term accreta sort of as a global all-encompassing term to describe these implantation abnormalities.

But you know, strictly speaking in accreta is the least severe.

And that's when you have attachment of the chorionic villi to the myometrium without invasion, that's the most common.

And in many of those patients actually will do quite well, even with a vaginal delivery if it's just a small area of adherence.

And in increta is when the villi partially invade the myometrium.

And then the worst and most severe is when you have a percreta when the villi invade through the myometrium and involve or extend beyond the serosa and invade adjacent structures, usually most commonly the bladder.

And I just wanted to review with you what the ultrasound features are here.

Again, this is going to be something that we're gonna see more in the second trimester and third trimester, but you can also have some clues to this diagnosis in the first trimester, I'll show you a paper dealing with that in a little bit.

So most of these patients will have a placenta previa.

And then one of the most prominent features that you'll see are these hypoechoic areas, which are referred to as these placental lacunae.

And if you see this, it actually has a very high positive predictive value for the presence of an at least an accreta.

Then you wanna look at the outer contour of the placenta.

Do you see a hypoechoic zone indicating the myometrium sort of outside of the placenta?

You wanna look carefully at the placenta bladder interface.

And I think it's very helpful.

You don't wanna have the bladder completely empty here.

You wanna make sure that it is somewhat distended so you can evaluate it. Again, use a combination of transabdominal and transvaginal, use your color doppler.

And in this case we saw that there were all these abnormal vessels here and there was actually extension of the vascularity from the placenta into the bladder in this patient with a placenta percreta.

This is a case we had about a month or so ago at Bellevue Hospital.

This was a woman at 22 weeks gestation.

She had a history of four prior C-sections.

She has a complete total placenta previa.

So without even looking at the images, you know that this woman is at extremely high risk.

But she did have all the classic features.

Here's the previa, she's got these lacunae, she's got all these abnormal vessels.

There was really no interface, no plane, between the placenta and the urinary bladder.

So we basically called this a placenta percreta.

She was counseled that probably the best option for her since she wanted to terminate the pregnancy was a grave hysterectomy.

And that is in fact what she underwent in the OR with the appropriate services available and on standby to help here.

And this was just the resident gave me these images.

This is a uterine wall.

This is where the placenta was indeed invasive into the uterus.

And this is actually a big defect here at the site of the C-section scar.

And you can see the membranes kind of poking through here.

It was just basically paper thin.

And so, you know, they were prepared for this.

They were forewarned and fortunately this woman did well.

We have been using MR in recent years as an adjunct to ultrasound for these implantation disorders.

I do not think it replaces ultrasound. We tend to use it.

Our MFMs refer patients where they pretty much are at very high risk and they have suspicious findings on ultrasound and they just sort of wanna get a sense of how severe the extent of the invasion is.

And basically again, you wanna have the bladder somewhat filled.

I think the three planar single shot fast spin echo or HASTE images are really the most important here.

Sometimes we'll do some smaller field of view, high resolution T2 weighted images as well.

Again, this is all in your handout and this paper kind of describes some of the features we look for on MR.

Namely, you're gonna see some bulging of the uterine contour.

You see these dark T2 hypointense bands which correspond to those lacunae that we see at ultrasound.

Also look at the border of the placenta here.

This was a percreta, it's very lobulated and in fact, it looks like there's abnormal signal within the urinary bladder.

So we call this a percreta.

You know, they did this case with GYN onc on standby.

They got urology involved. She did require a cystotomy.

And they also had IR put in balloon catheters so that they could insufflate the balloons to help tamponade the bleeding.

So it is important to recognize these abnormalities so that this multidisciplinary team approach can be used.

And this is in the coronal plane.

You see that invasion of the bladder there.

And then lastly, I just wanna mention that this is one paper where they do describe that even in the late first trimester many times you can get a clue that you're dealing with one of these disorders, such as a low implantation of the sac, these lacunae in the placenta irregularity of the placental myometrial interface.

In a patient with placenta previa and who's had a prior C-section, you need to alert the gynecologist and obstetricians to this possibility.

Conclusion

So with that, I'm going to finish.

And I think that in first trimester pregnancy, you have to use absolutely meticulous ultrasound technique.

Be aware of some of these new guidelines.

Again, we don't want to cause any harm to a pregnancy that could be normal.

I think you should be familiar with the typical and somewhat more unusual features of ectopic pregnancy.

Use 3D ultrasound and MRI as problem solvers, and then think about these placental implantation abnormalities.

Look for these features, particularly in high risk patients.

And with that, I thank you very much for your attention.