Bethany and Molly discuss how to monitor an Alloimmunized pregnancy. This is the first step to treating a sensitized pregnancy. Monitoring the antibody titer can indicate when you need MCA Scans, and intrauterine blood transfusions to keep your baby healthy.
Bethany and Molly discuss how to monitor an Alloimmunized pregnancy. This is the first step to treating a sensitized pregnancy. Monitoring the antibody titer can indicate when you need MCA Scans, and intrauterine blood transfusions to keep your baby healthy.
Episode themes:
Terminology used in this episode:
Anti-E Pregnancy Study: Moran P, Robson SC, Reid MM. Anti‐E in pregnancy. BJOG: An International Journal of Obstetrics & Gynaecology. 2000 Nov;107(11):1436-8. LINK
Survival rates for fetuses receiving IUTs: Lee L, Nasser J. Doppler ultrasound assessment of fetal anaemia in an alloimmunised pregnancy. Australasian Journal of Ultrasound in Medicine. 2010 Nov;13(4):24. LINK
Allo Hope Terminology Library https://allohopefoundation.org/library/terminology/
For more on tests during pregnancy, see our prenatal testing guide at https://allohopefoundation.org/library/prenatal-testing/
Research for this episode provided by Bethany Weathersby and Molly Sherwood of the Allo Hope Foundation. Find more information at https://allohopefoundation.org.
The Allo Podcast is produced and edited by https://www.mediaclub.co.
Bethany Weathersby:
The information shared on the Allo Podcast is not intended as medical advice.
Molly Sherwood:
Your medical care decisions should be made in consultation with your physician who is familiar with your specific case.
Bethany Weathersby:
Hi, welcome to the Allo Podcast from the Allo Hope Foundation. I'm Bethany Weathersby.
Molly Sherwood:
And I'm Molly Sherwood.
Bethany Weathersby:
In this episode, we are going to talk about monitoring, specifically, MCA Doppler scans. We'll discuss what they are, when they're needed and how we use them to monitor babies for fetal anemia. But first, Molly, how are you doing today?
Molly Sherwood:
Oh, today, I'm really glad that we don't do video recording on our podcast because I feel I'm like, I am a participant, or no, what is this person on the train of the Hot Mess Express? That is me.
Bethany Weathersby:
The passenger.
Molly Sherwood:
The passenger on the Hot Mess Express. I feel like I'm still recovering from my son's five year old birthday party this weekend.
Bethany Weathersby:
Nice.
Molly Sherwood:
And I know you also had a big birthday party for your son.
Bethany Weathersby:
We did. It was a 13 and 11 year old combo paintball party, which was the best day of their life. But let's just say, a lot of effort on the parents' part. So yeah, it was, yeah, I'm still recovering.
Molly Sherwood:
Yeah, that's how I felt. Plus having a five year old, he now cares about what we should do. It never used to be that way. And also he chose Angry Birds as his theme, which has not been in style for 12 years. So, I had to get a bunch of weird stuff from, used things on eBay and I had to make a bunch of my own decorations. It was just a little extra for me.
Bethany Weathersby:
Oh, you're a good mommy.
Molly Sherwood:
Anyway.
Bethany Weathersby:
I remember when my son asked me for an apocalypse themed birthday party a few years ago. He was like, "We can have down tower lines and things like on fire." And I was like, "No, not going to happen."
Molly Sherwood:
Awesome.
Bethany Weathersby:
Anyway, okay. So, here we go. Let's do it.
Molly Sherwood:
Okay, let's do this.
Bethany Weathersby:
So let's talk about the importance of monitoring during an Alloimmunized pregnancy.
Molly Sherwood:
Okay. Yeah. This is super important because it's important for a good reason, because HDFN is treatable, you just have to monitor it properly. Just painting the picture of the situation. We know that we're talking about a mother who has antibodies. This doesn't affect the mother herself, but she may have antibodies that can cause hemolytic disease of the fetus and newborn to their baby in utero or after birth, that can cause the baby to become anemic. And so, while you're pregnant, the goal is, let's just make sure we're keeping an eye on what's going on in utero to make sure we don't have to do anything.
Bethany Weathersby:
Right. Right. Or if we do need treatment, that we spot the anemia in time to treat it. Right?
Molly Sherwood:
Yes. Which is such an important point in your experience too, because I know you feel like had you had proper early monitoring, it would've saved Lucy's life.
Bethany Weathersby:
So during my first sensitized pregnancy, my starting titer was 1024, which just means I have a lot of antibody in my blood. And so, we knew that there was a lot of risk. And I also have anti-Kell, which can be more aggressive. So yeah, that was part of the problem was, I was asking my MFM team to start these MCA scans, start monitoring the baby for fetal anemia early and they didn't think it was necessary. And so, by the time they finally did agree to check the baby for fetal anemia, she was severely anemic and she died two weeks later. So, I know from personal experience how important monitoring is in this type of pregnancy. So, let's talk about how our babies are monitored.
Molly Sherwood:
I think there's sort of two main types of tests that are important during a pregnancy to monitor the status of the baby, noninvasive test, at least. One is the antibody titer, which I'll kind of talk about, I feel like. Because I have experience with titers since I always had low titer pregnancies, so I was always having my titers drawn. And then the other is an MCA scan, which is a noninvasive way to check if the baby has anemia. And that is totally your alley because you've probably had a bajillion of those.
Bethany Weathersby:
Right. Yes. So, it's pretty cool how in your pregnancy the disease was monitored through titers and in my pregnancies they were monitored through MCA scans.
Molly Sherwood:
Yeah, that's true. We kind of represent both ends of the spectrum.
Bethany Weathersby:
Yeah. Yeah.
Molly Sherwood:
Because my titers were never higher than four actually, in either of my pregnancies, even having two antibodies, never higher than four.
Bethany Weathersby:
Right. And then, mine was 1024 starting out. So let's talk about, what is a titer? What are titers?
Molly Sherwood:
Okay, so first of all, you draw a titer, we call it getting your titers drawn, but we're talking about the mom having a blood draw. So the idea is, it's measuring the amount, the level of antibodies in the mom's blood. So, it can help to tell you how much danger the baby may be in and that it will let you know, "Oh, there's a bunch of antibodies floating around in the mom's blood, so all the more potential to attack the baby's red blood cells." But on the flip side, they don't necessarily tell us if the baby is antigen positive or negative. I mean, you could have a super high titer and have an antigen negative baby, so the antibodies won't do a thing to the baby. And it doesn't actually tell us if the baby is being attacked by the mom's antibodies. It doesn't really tell us how the baby is doing at all. And as an aside, okay, can I throw in one of my favorite articles that was published on this, because I just can't help myself?
Bethany Weathersby:
Yes, you are the research lady. Go for it.
Molly Sherwood:
Okay. There was a study done a little more than 20 years ago, we can link to it, it was on anti-E pregnancies and they actually had a pretty remarkable enrollment. They had over a hundred women who had anti-E and 60 of those ended up having babies that were CMBS positive, meaning they were affected. Okay. So caveat, this is just ant-E, and each antibody can sometimes act differently and each mom can act differently. So, this is always with a grain of salt. But in this case, weirdly enough, the most severe disease was in a woman who had a titer of one.
Bethany Weathersby:
Wow.
Molly Sherwood:
So strange.
Bethany Weathersby:
So that would've been... Wow.
Molly Sherwood:
I know.
Bethany Weathersby:
That would've been missed, I guess it?
Molly Sherwood:
It would've been missed. Well, I guess, so it kind of was missed in that it didn't, nothing happened during that pregnancy to treat, but that baby received intervention after birth and the baby survived.
Bethany Weathersby:
Great. That's good.
Molly Sherwood:
On the flip side. The unaffected pregnancies in that study had titers all over the place. And it also concluded weirdly enough that, this is a quote straight from the article, "There was no correlation between cord blood, hemoglobin and the anti-E in these cases." No correlation. So-
Bethany Weathersby:
That's crazy.
Molly Sherwood:
... It's kind of unfortunate because it's like, this is just something that practitioners have developed to help to kind of triage the situation. It's not perfect.
Bethany Weathersby:
Yes.
Molly Sherwood:
But yeah, it's helpful. Oh, okay. And while I'm at it, since I have it up. Do you want to know what ended up happening to all those babies, what interventions they needed? I know, because everyone [inaudible 00:06:08] what happened.
Bethany Weathersby:
Of course.
Molly Sherwood:
Okay, so there was 62 babies that were CMBS positive, meaning they were affected by their mom's anti-E. And it was considered mild and 48 of them, moderate in eight, severe in five, and very severe in one. No infant, I think there was of fatality, but it was unrelated to HDFN. And so, only, let's see, it says 20 of the cases needed treatment. So 13 needed an exchange transfusion, which is after birth. Two needed another top up transfusion and one needed just a single top up transfusion. And then six just needed phototherapy.
Bethany Weathersby:
Wow. That's really comforting.
Molly Sherwood:
I know. Just a little bit reassuring. I will say though, that anti-E is kind of one of the ones that folks say are, is not one of the most aggressive ones. But it's just cool to have something with such high enrollment, it's really hard to find articles that have so many women in it, so I had to talk about it.
Bethany Weathersby:
Yeah. Nice. Okay, so the don't really tell us anything about the baby or how the baby is doing. So then what is the purpose of checking mom's titer?
Molly Sherwood:
I mean, it is imperfect like we're talking about. It's not intended to diagnose something, it's more of a screening tool. It's like hitting a threshold that then lets you know, "Okay, we need to start talking about MCA scans." So, the whole idea behind a critical titer, which for antibodies that are not Kell, a critical titer is 16. For Kell, it's four, but I've seen other institutions used two or really any titer. But it is simply to say that at titers of 16 or above, something could be necessary in terms of utero intervention. That's kind of all it was developed to tell you.
Bethany Weathersby:
Okay.
Molly Sherwood:
So it just means, "All right, time to go to the next step. We need to schedule an MCA scan."
Bethany Weathersby:
I did want to jump in here and just say that if your titer is extremely high, like hundreds or thousands, then it could indicate a need for early preventative treatments such as plasma phoresis and IVIG treatments. And if that is the case, these are usually done in the first trimester. So, that's why it's important to get this titer kind of early if possible, and then get in with your MFM to see if you need those treatments. But for me, my first titer was 1024 and so, I really did need those preventative treatments in order for my babies to survive, which I didn't get them with my first daughter, Lucy and she died. And then the next three, we were very careful about getting that titer at the beginning and getting those treatments started early and they were so helpful.
Molly Sherwood:
I feel like there's a misconception out there that you don't need to do anything until you see your high risk doctor at 16 or 18 weeks. I mean, that was the case for me. They were like, "Okay, you'll just wait 10 more weeks and then talk about it then." Which turned out to be okay in my case. But yeah, it's super important, just right off the bat, figure out your titer and then act from there.
Bethany Weathersby:
That's an easy test that your midwife can do, your regular ob. It's a very simple test. So, you can get that right away and kind of know what the next steps are. Back to what you were saying about the critical titer, if your titer is critical, you will need to go to the next type of monitoring, which is MCA doppler scan. So what... I'm sorry, I'm saying your part.
Molly Sherwood:
No, you need to tell me.
Bethany Weathersby:
I'm telling your part, so you need to-
Molly Sherwood:
You have to tell me what an MCA scan is. I've never had one. I've begged for them, just because I wish I could have one, but haven't had one.
Bethany Weathersby:
Why did you want one so bad?
Molly Sherwood:
I just want to know. It's just, the more information, the better.
Bethany Weathersby:
It's true. But really quick on that point. So many doctors think that the less we know, the safer we feel. But it's not true, it's really not true. For most of us women, the more we know, the safer we feel. Right?
Molly Sherwood:
I think that's true.
Bethany Weathersby:
Yeah.
Molly Sherwood:
Tell me what it even is.
Bethany Weathersby:
All right. So, an MCA Doppler scan is a specialized ultrasound that measures how quickly the baby's blood is flowing in the middle cerebral artery in the brain. And if the blood is flowing too fast, it can show that the baby is anemic. So, remember how we talked about titers don't tell us anything about the baby? Well, these MCA scans do tell us how the baby is doing. They show us if the baby is being affected by the mother's antibodies and if the baby is looking anemic or not. And that's what they're looking at. How fast is this baby's blood flowing in the middle cerebral artery in the brain?
Molly Sherwood:
Which is kind of counterintuitive to me because feels weird that it would be flowing fast for some reason. I don't know. So, why would an anemic baby have a faster blood flow?
Bethany Weathersby:
And I remember asking my doctors the same question. So they told me that, the consistency of the blood or the thickness and the way that it moves is different when the baby's anemic. And we know that anemia is not enough red blood cells. So blood that does not have enough red blood cells is thinner and flows more quickly. And then also another reason is, our red blood cells carry oxygen to our vital organs. So when there are not enough red blood cells, our body is oxygen starved. And to make up for this, the body pumps the blood faster in order to try to deliver more oxygen to the baby's vital organs. So this is why the speed of the blood flow is linked to fetal anemia.
Molly Sherwood:
Okay. This is super helpful. And also, I feel like we've said this plenty of times before, but it's worth repeating. This is not the same as a level two ultrasound or a high risk ultrasound or some kind of check in that you have at 18 or 20 weeks. This is a specific MCA scan ultrasound.
Bethany Weathersby:
Yes. Exactly. And it's looking at, I guess, kind of the baby's blood, which is not visible on regular ultrasound. Even in my case with Lucy, we had a very detailed in depth level two ultrasound when she was at 16 weeks and everything looked perfect and they did not do the MCA Doppler scan. And so, she was actually pretty anemic at the time and they said she wasn't because they weren't looking at the right thing. So, that's why these are so important. They're looking at, specifically, "Is this baby anemic or not?"
Molly Sherwood:
So, how do the doctors measure the blood flow and then how does that indicate anemia?
Bethany Weathersby:
The way they measure how fast the blood is flowing is called a PSV number, the peak systolic velocity. And so, this number is just the, straight up the speed of the blood flow.
Molly Sherwood:
Straight up?
Bethany Weathersby:
Straight up. But that's not the main number that we're looking at. And that's why this can kind of be confusing, at least it was for me. They have to use that PSV number in combination with your gestational age, so how many weeks pregnant you are at the time and they calculate something called an MOM, and that is the multiples of median. And that is the big number that we're looking at here. That will show us if the baby is in the safe zone or the danger zone for a fetal anemia. The reason why we have to calculate an MOM from the PSV is because babies' blood flows faster the further along they are in the pregnancy, if that makes sense. So a baby at 17 weeks will naturally have a slower blood flow than a baby at, say 27 weeks. And that's why we can't just look at how fast the baby's blood is flowing, we have to also look at the baby's gestational age and that's what calculates the MOM.
Molly Sherwood:
Okay. So, what MOM is a problem?
Bethany Weathersby:
So the MOM that you want to stay under is 1.5. That's kind of the cutoff. If your OM is under 1.5, it's considered safe. And I guess the normal, "normal MOM" is around one.
Molly Sherwood:
I kind of think of it mathematically, so we're literally talking about multiples of the median. So if the median is whatever it is, whatever the median PSV number is and yours is exactly the median, which is great, you are one times the median, one. So one is normal.
Bethany Weathersby:
Yes.
Molly Sherwood:
One is ideal.
Bethany Weathersby:
Right.
Molly Sherwood:
And then if you are 1.5, that means your PSV is 1.5 times more than the median. So that's a problem. You do not want to wait until you see visible signs of problems. You don't want to wait till you see fluid buildup or organ damage or high drops, because once it gets there, IUTs have lower survival rates. I was looking... You want to hear some more numbers?
Bethany Weathersby:
Yes, please.
Molly Sherwood:
Okay. This is from one study in one center, which is probably a pretty good center, but obviously it only represents one. And it mentions that survival rates for transfused fetuses are about 92%, if they're not hydropic. If they're hydropic, survival rate drops to about 70%.
Bethany Weathersby:
Wow. That is a big difference.
Molly Sherwood:
Yes. It's a huge difference. So all the more reason.
Bethany Weathersby:
Yeah. And in my own experience too. I've had four babies with HDFN and only one of them had fetal high drops and she died. And so yeah, the IUT was not successful at that point because the monitoring was not adequate. So we didn't catch the anemia until it was so far along that she had these visible signs, like fetal high drops.
Molly Sherwood:
On the note of other numbers. I wanted to say while we're talking about this, that MOMs are just an estimate. I mean, they're a great noninvasive tool, but they still can have a high false positive rate. And it's much better to have a false positive rate than anything else. False positive meaning that, it was showing that it was 1.5, meaning the baby's probably anemic, but maybe the baby really wasn't, that's a false positive. I'd way rather it be that way than the other way around of a false negative, right?
Bethany Weathersby:
Right.
Molly Sherwood:
But there is some evidence to show, when this first started coming out, that false positive rates were as high as 50%. Now they say close to 12%.
Bethany Weathersby:
Okay. So that's not super high.
Molly Sherwood:
No, it's not super high, but it's part of the reason why you have to double check and confirm that the baby is truly anemic by doing a cordocentesis right before you transfuse. Is that right?
Bethany Weathersby:
Yeah. So, that is done after the MFM sees the 1.5 or over MOM and then decides that he wants to move forward with that procedure. And so, yeah, the first thing in the IUT procedure is the cordocentesis to see exactly what the baby hematocrit and hemoglobin are.
Molly Sherwood:
Just to confirm. And that we shouldn't do that in two separate occasions. There's no reason to poke a baby once just to check their hemoglobin and hematocrit and then later schedule their IUT. The idea is you do it all in the same session when you're about to transfuse with the IUT, right?
Bethany Weathersby:
Yes. So they have everything set up for an IUT and then the needle is stuck into the baby's cord and a little bit of blood is pulled out and they test that blood to know exactly what baby's hematocrit is, to see if the baby is anemic or not. And that's the cordocentesis. So while they're waiting to see what hematocrit is, that needle they stuck in is still in there, it stays there.
Molly Sherwood:
That's crazy.
Bethany Weathersby:
They're not removing it because the more times you puncture the cord, the higher the risk.
Molly Sherwood:
And so, does a nurse just grab the blood and just bolt to a lab?
Bethany Weathersby:
Yes, yes. They run. There's a runner. That's someone's actual job, it's a runner.
Molly Sherwood:
That's crazy.
Bethany Weathersby:
And they run it to the lab and then the lab calls into the OR, to the doctor with the results. Or, so my doctor Moise, when he was treating me with my pregnancy with my daughter, Nora, he had a machine in the OR that would just calculate it right there. So there's nobody running anywhere. They draw the blood, put it in the machine and it gives the hematocrit right there.
Molly Sherwood:
That's so cool.
Bethany Weathersby:
So it's literally seconds. So the needle stays in, and then if the baby is actually anemic, they use that same needle and just filter the blood into the cord that way. So that's why you wouldn't want two separate procedures to check the hematocrit and then later come back and puncture the cord again unnecessarily, if that makes sense?
Molly Sherwood:
Yeah, that totally makes sense. I know you have notes because you kept notes through your pregnancies about your baby's MOMs. And then, did they actually have a relationship with the hematocrit?
Bethany Weathersby:
Yes. And I'll just share them with you really quick. And I do have the benefit of having four pregnancies all pretty severely affected, so you can kind of compare the four. But my first one, Lucy, her MOM was 2.5. Remember the cutoff is 1.5, so she was way over that cutoff. And her hematocrit was six. And your hematocrit should be around 40.
Molly Sherwood:
Wow. Yeah.
Bethany Weathersby:
So then, my next baby, Nora, her om was 1.56, so just over that line and her hematocrit was 26. So you can see that's different from her sister's hematocrit of six.
Molly Sherwood:
Yeah. But still definitely in need of an IUT.
Bethany Weathersby:
Yeah. That was the perfect time to have an IUT. And so then, my next baby Caelum, his MOM was 1.49. So his doctor was just being a little bit proactive. I mean, we knew how severe my disease was too, so he transfused. And the hematocrit was 28, so a little bit higher, you see how the lower MOM correlates with the higher hematocrit, if that makes sense. And then my last baby, August, his MOM was 1.55 and his hematocrit was 25.
Molly Sherwood:
How did their hematocrit change after they received an IUT?
Bethany Weathersby:
Oh, yeah. It all depended on how much blood the doctor gave and the method, but I believe all of them ended in the low forties.
Molly Sherwood:
All right. So, getting MCA scans. So when should you start doing these, and then how often after that?
Bethany Weathersby:
Yeah, the timing is really important with this type of monitoring, it's kind of time sensitive. So, if you have a critical titer, the MCA scans should start usually between 16 and 18 weeks, unless your titer is extremely high, like mine was, or you have a history of severe disease. So in those cases, you can start the MCA scans earlier, like 14 or 15 weeks.
Molly Sherwood:
And in those cases especially, but in all cases, they should be conducted by a tech or an MFM who's been trained specifically to do them.
Bethany Weathersby:
Yes, definitely. And at that point, with my last three pregnancies, I had very experienced MFMs who have done so many of these MCA scans. So my daughter, Lucy, they started around 18 weeks and it was too late, it was too late, she was already severely anemic. And that's why if you do have a titer in the hundreds or thousands, it's probably good to start closer to that 16 week mark or even 15 weeks. And then with my three youngest, I think we even started at 14 weeks just to be proactive. And they were great. We didn't have any issues with false highs or anything like that, but I had a very experienced doctor.
Molly Sherwood:
And then also, it's important that they take multiple readings. I think I've seen the recommendation is take three readings, but it's sort of up in the air whether you take the highest one or whether you take the average. But I think mostly it's important that it's just a clean scan, the baby is calm, the readings are about the same, to get a good feel. It's not just one. You don't take one assessment, you need at least three.
Bethany Weathersby:
Yes. My doctors always did, even way more than three actually.
Molly Sherwood:
Nice.
Bethany Weathersby:
But maybe that's because my babies were insanely active. I don't know. But yeah, we took a lot of readings for the MCA scans.
Molly Sherwood:
That makes sense to me. Why not, right?
Bethany Weathersby:
Yes, yes.
Molly Sherwood:
More data points.
Bethany Weathersby:
Yes, that's true. Also, let's talk about how often women should be receiving MCA scans.
Molly Sherwood:
Okay. So yeah, in terms of frequency, it's kind of unfortunate. I think recommendations say every one to two weeks. So that doesn't really tell you which one to do. But in general, the members of our medical advisory board kind of adopt this overall mentality that you just err on the side of closer monitoring. So, I think that we tend to say, "Go for every week.", right?
Bethany Weathersby:
Yes. Every week, once a week, unless it's getting close to that 1.5 MOM, you can go have a scan twice a week sometimes. But I have definitely seen fetal anemia develop in just a matter of days. And so, it's kind of scary to think if you're just being scanned every two weeks, it's scary to think that that fetal anemia could be missed.
Molly Sherwood:
What about, I know we say this a lot in our advocacy work when women are asking questions, what happens when the MOM is close to 1.5, what should you do? And also, what happens, this always seems to happen on a Friday. Doesn't it always happen, these women are like, "Oh, my MOM was 1.45. It's Friday, the doctor will scan me next Friday."
Bethany Weathersby:
Yes, yes. I mean, if it's getting close to the 1.5, it's good to move that next scan up closer. Scan within a couple days or whatever you and your doctor feel comfortable with. But if you feel uneasy about it as the patient, do speak up. I know the doctor makes the final decisions, but this is your child, this is your child's life and you are your child's voice. You're speaking because your baby can't speak for himself. And so, you are the voice of your baby. So just say, "I would feel more comfortable scanning again sooner". What are the benefits of waiting a whole week instead of two or three days and then what are the risks? Always look at the benefits and the risks.
Molly Sherwood:
Oh, that's a great question to ask yourself and also to ask the clinician. I feel like you can just directly ask that question, "What would the benefit be in waiting that long?"
Bethany Weathersby:
Right. Right.
Molly Sherwood:
Okay. So, that was an awesome tip. What are your other tips for patients who are getting MCA scans?
Bethany Weathersby:
This is really important. Ask your doctor for the PSV or the MOM every time you have a scan. A lot of times doctors do not offer that information to the patient unless they ask. A lot of patients will leave and then have concerns or something, and then they'll say, "Oh, I don't know what the numbers were, they didn't tell me." So just ask every time, "What's the PSV or what's the MOM?" And write it down, record it with your phone or something. Keep track of those numbers. They can be really useful in spotting fetal anemia.
Bethany Weathersby:
MOMs can fluctuate week by week, that's normal. It's not going to be a direct, exact line either up or down, they can kind of go fluctuate up, down, up, down. But if the baby is becoming anemic over the weeks, you can kind of see this upward trend in the MOMs. You're seeing a 1.3 and it's generally going up, up, up and then you get to that 1.5, it's easier to understand, the baby's probably anemic, rather than if you're not recording and you can't remember what the previous numbers were. And then you get at 1.5, it's like, "Is this..."
Molly Sherwood:
Is it a false high? Yeah.
Bethany Weathersby:
... Yes. Yeah. So, just record those numbers and those numbers can help exactly how your baby's doing. And then also with future pregnancies, you can compare these numbers with your previous baby. This was so helpful with my pregnancies. And even my doctor would say, "Can I see that notebook of yours and look at your previous pregnancy at this week. Let's see where you were at this exact gestation." And that was really, really helpful. So just record those numbers. And also, it's helpful to go into the scan knowing exactly what PSV equals a 1.5 MOM for that gestation. So, I would look at it ahead of time and see like, "Okay, I'm 16.5 weeks. So, what would a PSV that will equal 1.5 now for me?" And I'll have that number in my head, so that while they're scanning, I'm watching, and I can know right away, "Oh shuu. We're fine. We're fine."
Molly Sherwood:
Isn't it funny how that's so valuable just to know one minute sooner?
Bethany Weathersby:
Yeah.
Molly Sherwood:
You just need to know.
Bethany Weathersby:
It is, otherwise, I mean, then you're at the mercy of the ultrasound tech or the doctor who's doing the reading. And are they going to do the calculation themselves? Then there's this wait. But if you can just watch it and automatically know, "Oh yes, my baby's fine." You can roughly just double your gestation to know what the PSV number is to stay under. Let's say I'm 20 weeks pregnant, I go in and then I'm like, "Oh, I didn't figure out the calculation ahead of time." So I can know that I need to stay under 40, because that's double my gestational age. I need to stay, the PSV needs to be under 40.
Molly Sherwood:
That's cool. I didn't know that. I like that trick just to give you a feel without having to memorize.
Bethany Weathersby:
Yes. And then also, for those who want to calculate their MOM. If you just have your PSV, you can go to this really easy to use calculator online, you just plug in your gestational age and your PSV and it tells you baby's MOM. And it even says under that, "Anemic, or moderately anemic, or not anemic." and that just helps the patient kind of know where the baby is. And we will link to that calculator in the show notes. So, make sure that if they're only taking one or two readings during your scan, you can ask, "Can you just do a few more readings for peace of mind?"
Molly Sherwood:
Yeah. I find it easy, sometimes it helps to put the blame on yourself like, "Hey, just to put me at ease, I know I'm a crazy lady, but just go ahead, just a few more reading would be great."
Bethany Weathersby:
Yes. Yeah. I've definitely done that many times.
Molly Sherwood:
Okay. So let's wrap this up. It's super important to do this monitoring and MCAs are the best noninvasive way to tell us how our baby is doing. And now I feel like I need to issue a caveat to the low titer mom like myself. Stay diligent with your titers and focus on delivery, prepare for deliveries. So just because your titers don't merit an MCA scan doesn't mean that the baby won't need intervention after birth. So it just means that research has shown that babies with low titers don't need intervention in utero, that's what that threshold is for titers. So anyway, that's something to keep in mind. Because I feel like all moms, myself included, we're so focused on pregnancy. If you have the time to look into it, we can start thinking about after birth care too.
Bethany Weathersby:
I did also, I just remembered something I wanted to add. If you have had an affected pregnancy in the past, you should have MCA scans regardless of what your titer is now.
Molly Sherwood:
Yes. And on top of that, if your titers have ever crossed the threshold of 16, even if they went back down, once critical, always critical. Once it's critical, you now qualify for MCA scans.
Bethany Weathersby:
Yes. Or four for Kell.
Molly Sherwood:
Yes, correct.
Bethany Weathersby:
Yeah. I remember helping a patient, she had a titer of four and then it went down to one and kind of fluctuated between one and two and never went back up to four. And then she did need intrauterine blood transfusions. The baby became anemic. And so, I was just so thankful for a doctor who was doing the weekly MCA scans. And she had Kell. She Kell, yeah.
Molly Sherwood:
Okay. Yeah. Oh yes.
Bethany Weathersby:
Yeah. But they could have said, "Oh. Well, now your titer is one, so no need for the scan. But yes.
Molly Sherwood:
It's such an imperfect science, which is really-
Bethany Weathersby:
I know.
Molly Sherwood:
... it is what it is. It's a rare disease, it's super strange how it behaves in each woman's body, but just all the more reason to go ahead and be proactive and just watch what you can and monitor what you can monitor.
Bethany Weathersby:
Yep. Exactly. Okay. So on the topic of monitoring, quick reminder, the two types of non-invasive monitoring. There's titers and MCA Doppler scans.
Molly Sherwood:
And the titer measures the level of antibodies in the mom's blood, doesn't tell you how the baby's doing. You have a cool analogy that you've said before about the shark thing. What's that shark story?
Bethany Weathersby:
Yeah. Okay. I'll just try to do this really quickly. But it kind of helps give just a picture of this whole titer thing. And it's just like, imagine that you are standing on the beach, you're looking out over the ocean, the waves are coming in and your baby is out there in the ocean under the water. And it's kind of like when you're pregnant, your baby is out of sight.
Molly Sherwood:
True.
Bethany Weathersby:
You can't see your baby. You know your baby's right here, but you can't see them. And so, just imagine your baby's out there in the water, can't see the baby, but you know he's there. And so the antibodies are like sharks. There are sharks in the water with your baby. The titer tells you exactly how many sharks there are in that water. So, if there's one shark, your baby has a very low chance of being attacked by the shark. But if there are thousands of sharks, you know, "Uh-oh. This is really dangerous right now." And so, that's what the titer is for. It's telling you, "This is how many sharks there are in the water with your baby."
Bethany Weathersby:
And the MCA scan, that's like going under the water and getting eyes on the baby and seeing, "Oh, my baby's fine". Or the baby is, there are sharks approaching the baby. And so, that's what the MCA scan tells us. You can look at the baby and see if the baby's safe or not. So that's just kind of a good picture.
Bethany Weathersby:
And by the way, really quick, we didn't mention this either. If the baby is antigen negative, that's like your baby is up on the beach, laying on a beach towel, taking a nap, totally safe.
Molly Sherwood:
Yes. I like that.
Bethany Weathersby:
That baby cannot be affected by those sharks, no matter how many sharks are out there. That baby who's antigen negative is completely safe. And so, there's no need to do MCA scans or even check the titers because you know the sharks cannot get your baby, the antibodies cannot affect the baby. So all of this that we're talking about is only for babies who we know are antigen positive or we're not sure, they could be. But if you know the baby is antigen negative, you don't need to know any of this that we just talked about.
Molly Sherwood:
Sorry, we should have started with that so that people could just turn it off.
Bethany Weathersby:
We should have.
Molly Sherwood:
It's still good to know.
Bethany Weathersby:
Yeah, yeah. Yes.
Molly Sherwood:
What else? Oh, okay. Just talk about, real quick, how often, again?
Bethany Weathersby:
Yes. If you have a critical titer, MCA scans should start by 16 to 18 weeks and be done weekly unless you have a titer in the hundreds or thousands and then maybe you could start MCA scans earlier, 14, 15, 16 weeks.
Molly Sherwood:
And then they continue until, here we go, another caveat. They say that the titer, or I'm sorry, not titer, MCA scans are not super reliable after 35 weeks. So that's another reason, that's a contributing factor to why women with antibodies, if their baby is affected or could be affected, are induced or deliver at 37 to 38 weeks. Because you stop really being able to get a good picture of what's going on with MCAs.
Bethany Weathersby:
Right.
Molly Sherwood:
Yeah.
Bethany Weathersby:
Right. That's true. And that's super important. Even if you have not needed intervention, even if your titer is not critical, it's recommended to deliver between 37 and 38 weeks.
Molly Sherwood:
Yeah, that's true. And also, overall, I feel like this is sort of a... I consider this podcast kind of a positive one because we know HDfN is treatable and this is the stuff that enables us to treat. This is good stuff. These are great resources that so long as we find a practitioner to partner with that feels comfortable with doing the same things, we're hopefully golden or just, we're doing the best we can.
Bethany Weathersby:
Yes. And I do want to add really quick. I remember, I kind of have the worst case scenario according to several doctors. And I remember after my first daughter died from this disease, I had some friends who also had, they lost their babies to still birth and they didn't know the cause of their baby's deaths. And I remember all of us together thinking about future pregnancies and it's weird, but there was this comfort for me because I knew exactly what had happened and I knew that it was treatable and I knew that we could have this monitoring that we just described and that could lead to correct treatment and then a safe baby. And then I did. I was able to have three more healthy, safe babies. And so yes, it is scary. It can be scary, but it is treatable. And you can have healthy babies despite antibodies.
Molly Sherwood:
Yes. And how lucky are we that this is a temporary disease?
Bethany Weathersby:
Right. Yes.
Molly Sherwood:
Temporary.
Bethany Weathersby:
Yes. My three kids are just now living their lives, they're crazy lives and we don't have to think about this at all
Molly Sherwood:
Except for when you do it at work every [inaudible 00:31:01]
Bethany Weathersby:
That's true. That's true. So we did it. We covered it all, I think. Right, Molly?
Molly Sherwood:
Yeah. Totally everything. Well, we tried. It's like-
Bethany Weathersby:
Yeah, we did our best.
Molly Sherwood:
... we did our best. That's encouraging. We did our best. I do think, I mean, the goal is always, we can't share everything, nor do we know everything. But the goal is, what can we share that will give every mother at least the bits they need to know to feel in control and empowered to manage this.
Bethany Weathersby:
If you, your partner or someone close to you is experiencing Alloimmunization or HDFN, please know that we are here for you. We have a great resource library on our website @allohopefoundation.org. That's allo, spelled A-L-L-O hopefoundation.org.
Molly Sherwood:
Thanks for listening. The Allo Podcast is a production of the Allo Hope Foundation. It was researched and written by Bethany Weathersby and me, Molly Sherwood. It is produced and edited by CJ Housh and Eric Hurst of Media Club. The Allo Podcast is sponsored by Janssen Pharmaceutical Companies of Johnson & Johnson.