Knocked Up Podcast - What is a molar pregnancy?
A listener request - send yours to podcast@womenshealthmelbourne.com.au
What is a molar pregnancy?
Listener request! What is a molar pregnancy? How are they detected? How are they treated? Do they reoccur?
For more on molar pregnancies, check out this blog
Hosted by Dr Raelia Lew and Jordi Morrison
Dr Raelia Lew is a RANZCOG Board Certified CREI Fertility specialist, Gynaecologist and the Director of Women’s Health Melbourne.
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Have a question about women's health? Is there a specific topic you'd like us to cover? Email podcast@womenshealthmelbourne.com.au. We keep all requests anonymous.
TRANSCRIPT
Women's Health Melbourne is an innovative, holistic fertility and women's health practice. We are world leaders in IVF and egg freezing and provide our patients with every opportunity to achieve their goals. Our handpicked expert team provides the ultimate care experience for our patients. Reach us at women'shealthmelbourne.com.au and follow us at women's health melbourne and @doctorraelialew. Hello, and welcome back to Knocked Up, the podcast about fertility and women's health.
Jordi Morrison: You are joined as always by me, Jordi Morrison, and doctor Raelia Lew, CREI fertility specialist. Welcome, Raelia.
Dr Raelia Lew: Welcome, Jordi.
Jordi Morrison: Raelia, do you wanna introduce today's topic, molar pregnancies?
Dr Raelia Lew: Molar pregnancy is a topic that I was asked to cover by one of my patients, not for herself, but because she had a friend who had experienced a molar pregnancy. And when she talked to her friend about it, she really knew nothing about it herself.
Jordi Morrison: Well, good place to start. What is a molar pregnancy?
Dr Raelia Lew: A molar pregnancy is a rare complication of pregnancy that causes a special type of miscarriage. It involves unusual growth of trophoblasts, which are the cells that make the placenta and that are derived from the trophacter derm, which is the outer cell layer of an embryo. And these cells can have an abnormal genome or abnormal genetic makeup into different ways. So there are two different types of molar pregnancy. The first is called a complete molar pregnancy, and sometimes that's called a complete mole. And in a complete molar pregnancy, we see the placental tissue swelling and making fluid filled cyst or grape like cysts. In a complete molar pregnancy, there is no baby. In a complete molar pregnancy, and we can talk about this in more detail a bit later, but there is no maternal DNA. The maternal DNA is completely lost and there is only paternal DNA. Another type of molar pregnancy is called a partial molar pregnancy. That's where there's some maternal DNA, but there's also too much paternal DNA. There can be a foetus in a partial molar pregnancy, but it usually miscarries quite early on and it cannot survive. So neither a partial or a complete molar pregnancy is a viable pregnancy that could ultimately result in the birth of a baby.
Jordi Morrison: When would you find out if you have a molar pregnancy?
Dr Raelia Lew: With modern technology, like ultrasound where we see abnormal findings on a scan, molar pregnancy is generally diagnosed in the first trimester. But as we'll discuss later, when we talk about some of the complications of molar pregnancy, It used to be in olden times that molar pregnancy was sometimes detected much later on.
Jordi Morrison: Why are molar pregnancies different to other types of miscarriages?
Dr Raelia Lew: Molar pregnancies are unique in that they can have really serious complications, including turning into a form of cancer. A molar pregnancy for that reason requires intervention and and close monitoring and treatment. Sometimes with a spontaneous miscarriage of a more benign type where something just goes wrong and the baby doesn't form properly and the miscarriage could be managed in various ways, we often talk about spontaneous resolution where we just watch and wait, or you might have a medical management where you give some medications to end a pregnancy when it's clear that it's not gonna make a baby, or we can do a suction curettage. If we suspect a molar pregnancy, we're gonna be much more proactive.
Jordi Morrison: Are there any particular symptoms of a molar pregnancy?
Dr Raelia Lew: Often not. And sometimes a molar pregnancy is detected at the time of a miscarriage, which is initially treated like any other miscarriage. Molar pregnancies can seem just like a regular pregnancy, but they can cause symptoms. Sometimes symptoms can be bleeding in early pregnancy, although that's not the only reason for bleeding in early pregnancy. Molar pregnancies are often associated with a really high level of the hormone beta hCG, and for that reason, they can present with more severe nausea and vomiting or hyperemesis gravidarum because that is caused by high levels of hCG. Having said that, some women experience that with a normal pregnancy as well. Sometimes, and this can be quite scary, grape like cysts can pass from the vagina and be expelled from the pregnancy. And that's because that is the structure of tissue made by the abnormal placenta of a molar pregnancy, but that can happen. And sometimes pain, pelvic pain and pressure can be a symptom of molar pregnancy, but that can also be a symptom of a normal pregnancy as well. Usually, as we discussed, molar pregnancies are found in the first trimester, But if for whatever reason, someone doesn't have antenatal care and a molar pregnancy persists into the second trimester, sometimes signs might be that a uterus is growing much too quickly and the uterus is getting bigger much faster than you would anticipate for that gestation of pregnancy. You can also have symptoms of preeclampsia of early onset associated with a molar pregnancy. Preeclampsia is a condition where you have high blood pressure and protein in the urine during pregnancy, and that can occur before twenty weeks of pregnancy with a molar pregnancy. And because of the hormones secreted by the molar pregnancy, sometimes it can be associated with ovarian cysts. And because HCG, which is the hormone made in high levels by the molar pregnancy, can stimulate the thyroid because there's a very close physical relationship between the structure of HCG and the structure of thyroid stimulating hormone, sometimes symptoms of hyperthyroidism are present in someone with a molar pregnancy.
Jordi Morrison: And do we know what causes a molar pregnancy?
Dr Raelia Lew: We do. So a molar pregnancy is when an egg is fertilised atypically. So it can be fertilised by a sperm and then the egg loses the mother's DNA for whatever reason, the x chromosome and the maternal genome entirely is lost or doesn't work. And so the farm the father's chromosome or the sperm derived chromosomes are copied and the whole DNA from the baby and the pregnancy. Oh, well, there isn't a baby. It's a pregnancy, but it's not there's no foetus comes from the paternal DNA. So a sperm DNA derived genome without the egg cannot make a baby, but it can make a pregnancy and it can make a pregnancy that behaves like a cancer. In a complete molar pregnancy, you can have that happen with either one or two sperm fertilising an egg. A partial mole is when the mother's chromosomes are present, but the, or the eggs chromosomes are present, but there are two sets of paternal chromosomes. So that's when two sperm fertilise an egg. We're meant to physiologically have this gatekeeper function that when one sperm gets into an egg, the egg kind of shuts down at stores and doesn't let any more sperm in. But sometimes like anything in biology, that process goes wrong. And that is the reason for a molar pregnancy, having only paternal genome active or having a dominant paternal genome active.
Jordi Morrison: Are there any risk factors for having a molar pregnancy? Are they more likely to happen to some people?
Dr Raelia Lew: There are. So if you have had a molar pregnancy before, you're more likely to have one again compared to other people. What that tells us is that there might be some genetic susceptibility factors that your eggs may be more likely to be penetrated by two sperm, maybe because your gatekeeper function isn't as good as other people. The age of the mother interestingly is a risk factor, and it's a risk factor if women are older than 43, but also in early teenage pregnancies. So if women are younger than 15, that has been an observed risk factor. We don't know why that is. It might be that eggs either are not yet at their best or they've kind of passed their prime, and that makes them more susceptible to being fertilised by multiple sperm.
Jordi Morrison: So if you've frozen your eggs, but you don't use them until you're over 43, you do your best at avoiding this?
Dr Raelia Lew: Yeah. So if you freeze your eggs, the age that you use them is irrelevant to their biology. They exhibit features of the biology of the egg at the age that you were when you froze your eggs. So if you freeze your eggs when you're 30, but you only use them when you're 40, your eggs will behave like 30 year old eggs even though you're 40.
Jordi Morrison: At the beginning, you mentioned that a complication of molar pregnancy can be cancer. That sounds a bit scary. What can you tell us about that?
Dr Raelia Lew: Molar pregnancy tissue or trophoblastic tissue can behave like a cancer. So it can locally invade, and it can also act like a cancer and metastasise, meaning spread to distant sites around the body in the bloodstream and form tumours elsewhere in the body. It can be fatal. It is given the name gestational trophoblastic disease or gestational trophoblastic neoplasia when this happens. Happily, this type of cancer is actually very susceptible in most cases to chemotherapy, and that's how we treat it. So it is really like an aggressive cancer, but it can be treated with chemotherapy. One sign that someone might be at risk is if they've had what's called a D and C after a molar pregnancy and the HCG hormone levels don't fall or they persist at a low level for a long time. If you have confirmed molar pregnancy on products of conception after D and C, your doctor will be tracking your HCG level until it's negative. And if it doesn't go negative, you'll be likely recommended treatment with chemotherapy. And a common chemotherapy used is a drug called methotrexate. Chemotherapy is scary, but it's very good at ensuring that you don't have an advanced cancer proceed from a molar pregnancy that can threaten your life. So it is really important. There is also, in some people, a possibility of treatment being the removal of the uterus or hysterectomy. So if you have severe gestational trophoblastic disease in the uterus, it's growing as a tumour in your uterus and chemotherapy is not getting rid of it, then some people would be recommended to have a hysterectomy, which is removal of the uterus. So that means you won't be able to carry a baby in the future yourself. You can still have a baby by gestational surrogacy in that situation. So the rare cancer form of gestational trophoblastic disease is called choriocarcinoma. It can spread to distant organs, so that's when we call it a choriocarcinoma, when it spreads to the lung or it spreads to the spreads to the liver, in a way that cancer can. And, this is usually successfully treated with chemotherapy. It's only a complete mole usually that causes this problem. It is technically possible for a partial mole to cause this problem, but we're much more worried about a complete molar pregnancy causing a choriocarcinoma. To make sure that a molar pregnancy has fully resolved, we always watch that hCG level till it goes to zero. And it can be recommended it's usually recommended if we've been worried about it that you don't get pregnant again for at least six to twelve months, and that's because we can't tell the difference if your hCG rises with a new pregnancy, if it's return of the cancer, or if it's a new pregnancy. And if you do get pregnant and you get a return of the cancer, well, chemotherapy will harm your baby, and you'll have to have a termination, you know, to save your life with chemotherapy. So we usually say, don't get pregnant again until we're sure that it's safe for you. That can be really frustrating for patients because they have grieved the loss of their pregnancy, and then they're told that they can't get pregnant again for quite a long time. And that can be exacerbated by other factors if the woman is older or if she's been trying to have a baby for a long period of time.
Jordi Morrison: Is there anything someone can do to make sure that they don't have another molar pregnancy?
Dr Raelia Lew: They can come and see their friendly IVF doctor. What I have done for actually quite a few patients over the years in this situation, because often they've had their chemotherapy, they've had a washout period, so their chemo's out of their system. That that's important because chemotherapy can injure eggs in your ovary and it can cause birth defects in babies. So we wouldn't want to do any fertility treatment in the first few months after having had chemotherapy. There are some patients who have had a molar pregnancy. They've had something like a D and C, confirm their molar pregnancy, and haven't needed chemotherapy, but are in that holding pattern where we're just waiting to make sure it doesn't come back and tracking their HCG at zero. What we can do in in that situation is do an IVF cycle, and we can collect eggs, fertilise them with ICSI so we know that only a single sperm will get into the egg because we pick it up with a little micro injector and inject a single sperm into each egg. And then we can do genetic testing of embryos to make sure that each embryo has got a balanced genome that's called PGTA, and this will reduce someone's risk to almost zero of a molar pregnancy. So the other thing that that achieves is banking embryos so that a woman has reduced fertility anxiety during the time that she can't get try and get pregnant. So having those embryos in the bank can sometimes be really mentally helpful because she knows that she'll have opportunities. She's not unable to create opportunities for herself to have a baby. And potentially if that delay of her pregnancy is really worrying to her, that can be very soothing to have those embryos frozen. Strategically, it also means that the time that you need to wait, be it six months or a year, you know, what what that actually does is the time that you delay having your first child will also impact the age you are when you attempt further children. So it does influence things like inter pregnancy interval and just the chance overall of being able to have another baby. So having those embryos in the freezer can be really reassuring, but it can also be very powerful in helping a woman achieve her desired family size over time in the context of her unwanted delay.
Jordi Morrison: Thank you, Raelia. Really good to get an overview of a topic like this. To support Knocked Up, leave us a review or recommend to a friend. Join us on Instagram at @knockeduppodcast and join Raelia at @doctorraelialew, and email us your questions to podcast@womenshealthmelbourne.com.au.