Molar pregnancy
Molar pregnancy
A molar pregnancy happens when a fertilised egg ends up with the wrong amount of genetic material inside it, either too much or too little. Because of this problem, the egg is never able to grow into a baby.
This is a very rare condition. Out of every 600 pregnancies, only 1 turns out to be a molar pregnancy.
Types of molar pregnancy
There are 2 main types of molar pregnancy.
Complete mole
A complete mole forms when a fertilised egg has too little genetic material inside it. This usually happens when a single sperm fertilises an egg that has no genetic material of its own, sometimes called an "empty" egg. Since there is no genetic material inside, a baby has no way to develop. Instead, clusters of abnormal cells grow in your womb. This is known as molar tissue.
A complete molar pregnancy will still give you a positive pregnancy test, and you will still notice pregnancy symptoms. This happens because of the molar tissue.
Partial mole
A partial mole forms when a fertilised egg has too much genetic material inside it. This can happen in one of two ways: either 2 sperm end up fertilising a single normal egg, or an egg already carries double the usual amount of genetic material even before it is fertilised.
Because there is too much genetic material in this case, a baby cannot fully develop from a partial mole either. Instead, clusters of abnormal cells, again called molar tissue, grow inside the uterus (womb). On an ultrasound scan, a baby may sometimes be visible, but it will be smaller than expected for its stage, and it will not be able to survive to full term.
Even when no baby can be seen on the ultrasound scan, the molar tissue itself is enough to cause a positive pregnancy test, along with the usual pregnancy symptoms.
Common Symptoms
⚠️ This symptom list is for educational purposes. Having these symptoms does not mean you have this condition. See a doctor for proper diagnosis.
Medicines Commonly Used
⚠️ These medicines are commonly used for confirmed diagnoses of this condition. This is NOT a recommendation or prescription. Treatment must be determined by your doctor.
No medicines have been linked to this condition yet.
Causes
Causes of a molar pregnancy
Molar pregnancies are caused by problems with the genetic information in an egg or sperm. It’s not known what causes the problems with genetic information.
There are some factors that can increase the risk of molar pregnancy. You’re more likely to have a molar pregnancy if:
- you’re a young person (under 18 years)
- you’re over 45 years old
- you’re of Asian origin
- you’ve had a molar pregnancy before
- you have a diet that is low in vitamin A
Even if you fit into several of these categories, it’s most likely that you’ll not have a molar pregnancy. It’s still a rare condition. You’re just a little more likely to have a molar pregnancy than those who do not fit into these categories.
Diagnosis
Most molar pregnancies are picked up during a routine ultrasound scan, when the images appear unusual. That alone isn't enough to confirm a molar pregnancy, so you'll also be offered a blood test to be sure.
In some cases, a molar pregnancy leads to an early miscarriage before it's even diagnosed. If this happens, you would only learn it was a molar pregnancy from tests carried out after the miscarriage.
Treatment
Treating a molar pregnancy
A molar pregnancy cannot develop into a baby. There’s no way to correct the amount of genetic material in the fertilised egg. This means you’ll need to have surgery to have the pregnancy removed.
Some people develop a gestational trophoblastic neoplasia (GTN) after a molar pregnancy. This is a rare, but highly curable, form of cancer.
After your surgery, you’ll be registered with the Hydatidiform mole follow-up centre. This centre is within Ninewells hospital in Dundee. They’ll provide follow up appointments and monitor you for signs of GTN. They do this by checking the level of hCG (a pregnancy hormone) in your blood and urine (pee).
The centre will work with your local GP to do the blood and urine tests. You’ll not need to travel to Dundee to have these tests done.
It’s important that you do not become pregnant again before finishing follow-up treatment. A new pregnancy will cause your hCG levels to rise. This means the specialists cannot tell if you’ve developed GTN.
Gestational trophoblastic neoplasia (GTN)
GTN is very curable type of cancer. It can be caused by the molar tissue growing in your uterus.
Over 99% of people with GTN make a full recovery.
GTN is usually diagnosed because specialists detect high hCG in your blood or urine (pee). Unusual vaginal bleeding can also be a sign of GTN.
These specialists will discuss treatment options with you. You may be offered:
- surgery to remove the tissue
- chemotherapy
If you have GTN, you should not become pregnant for a year after finishing chemotherapy. This is because, in rare cases, the GTN could come back.
Getting pregnant after molar pregnancy
Having a molar pregnancy should not stop you from getting pregnant again.
If you’ve had a molar pregnancy before, the risk of you having another is higher than a person who has never had one. But this risk is very small. Only 1 in 80 people who’ve had a molar pregnancy will have another.
Support after a molar pregnancy
Experiencing a molar pregnancy can be a difficult time emotionally. You may grieve for your lost baby, and feel frustration because no one can explain why this happened.
You may also feel anxious about GTN, especially as you wait for your follow up treatment to finish.
Read more about coping after losing a baby
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