Topic Overview
What is a molar pregnancy?
A molar pregnancy
happens when tissue that normally becomes a
fetus instead becomes an abnormal growth in your
uterus. Even though it isn't an
embryo, this growth triggers symptoms of pregnancy.
A molar pregnancy should be treated right away. This will make sure that
all of the tissue is removed. This tissue can cause serious problems in
some women.
About 1 out of 1,500 women with early pregnancy
symptoms has a molar pregnancy.
What causes a molar pregnancy?
Molar pregnancy is
thought to be caused by a problem with the genetic information of an egg or
sperm. There are two types of molar pregnancy: complete and partial.
- Complete molar pregnancy. An egg with no
genetic information is fertilized by a sperm. It does not develop into a fetus but continues to grow as a lump of abnormal tissue that looks a bit like a cluster of grapes and can fill the uterus.
- Partial molar pregnancy. An egg is
fertilized by two sperm. The placenta becomes the molar growth. Any
fetal tissue that forms is likely to have severe
defects.
Sometimes a pregnancy that seems to be twins is
found to be one fetus and one molar pregnancy. But this is very rare.
Things that may increase your risk of having a
molar pregnancy include:
- Age. The risk for
complete molar pregnancy steadily increases after age 35.
- A history of molar pregnancy, especially if you've had two or more.
- A history of miscarriage.
- A diet low in folic acid or carotene. Carotene is a form of vitamin A. Women
who don't get enough of these vitamins have a higher rate of complete molar
pregnancy.
What are the symptoms?
A molar pregnancy causes
the same early symptoms that a normal pregnancy does, such as a missed period
or morning sickness. But a molar pregnancy usually causes other symptoms too.
These may include:
- Bleeding from the vagina.
- A
uterus that is larger than normal.
- Severe nausea and vomiting.
- Signs of
hyperthyroidism. These include feeling nervous or
tired, having a fast or irregular heartbeat, and sweating a lot.
- An uncomfortable feeling in the pelvis.
- Vaginal
discharge of tissue that is shaped like grapes. This is usually a sign of molar
pregnancy.
Most of these symptoms can also occur with a normal
pregnancy, a multiple pregnancy, or a miscarriage.
How is a molar pregnancy diagnosed?
Your doctor
can confirm a molar pregnancy with:
- A blood test to
measure your pregnancy hormones.
- A pelvic ultrasound.
Your doctor can also find a molar pregnancy during a
routine
ultrasound in early pregnancy. Partial molar
pregnancies are often found when a woman is treated for an
incomplete miscarriage.
What are the risks of having a molar pregnancy?
A
molar pregnancy can cause heavy bleeding from the uterus.
Some
molar pregnancies lead to gestational
trophoblastic disease, a growth of abnormal tissue inside the uterus. Sometimes this tissue keeps
growing after the molar pregnancy is removed.
- Complete molar pregnancies: Out of 1000 cases of complete molar pregnancy, 150 to 200 develop
trophoblastic disease that keeps growing after the tissue is removed. This means that in the other 800 to 850 cases, this doesn't
happen.
- Partial molar pregnancies: Out of
1000 cases of partial molar pregnancy, about 50 develop trophoblastic
disease. This means that in 950 cases out of 1000,
this doesn't happen.
In a few cases, trophoblastic disease turns into cancer.
In rare cases, the abnormal
tissue can spread to other parts of the body.
Almost all women who get this cancer are cured with
treatment.
How is it treated?
When you have a molar
pregnancy, you need treatment right away to remove all of the growth from your
uterus. The growth is removed with
a procedure called vacuum aspiration.
If you are done having children, you may decide to have your uterus removed (hysterectomy) instead of having a vacuum aspiration to treat your molar pregnancy.
After treatment, you will have regular blood tests to look for signs of
trophoblastic disease. These blood tests will be done over the next 6 to 12
months. If you still have your uterus, you will need to use birth control for the next 6 to 12 months so you don't get pregnant. It is very important to see your doctor for all follow-up visits.
If you do get trophoblastic disease, there's a small
chance that it will turn into cancer. But your doctor will likely find it early
so it can be cured with
chemotherapy. In the rare case when the cancer has had
time to spread to other parts of the body, more chemotherapy is needed,
sometimes combined with radiation treatment.
Trophoblastic
disease doesn't keep most women from becoming pregnant later.
After a molar pregnancy, you may feel very
sad and worry about cancer. It may help to find a local support group or
talk to your friends, a counselor, or a religious adviser.