Diseases Treated

Gestational Trophoblastic Disease/Molar Pregnancy

What is molar pregnancy?

Under normal circumstances, pregnancy begins when a sperm unites with an egg. The fertilized egg then develops by dividing into two groups of cells, which ultimately form the placenta and the fetus. The placenta is the organ that is attached to the wall of the uterus and provides nourishment for the developing fetus. A molar pregnancy develops as a result of faulty fertilization. This leads to abnormal placental development, which in turn leads to the failure of fetal development.

There are two types of molar pregnancies - complete and partial A complete molar pregnancy develops when the placenta is completely made up of small cystic structures that fill the uterus instead of developing into a pancake-like structure attached to the wall of the uterus. Because the placenta is completely abnormal, the fetus does not develop at all.

A partial molar pregnancy develops when the placenta is partially made up of small cystic structures. Because the placenta is partially abnormal a fetus develops but is always abnormal. The precise cause of molar pregnancy is not known. However, we do know that this condition occurs in approximately 1 to 1,000 live births in this country.

When and how do you know the pregnancy is abnormal?

Your molar pregnancy probably began with the usual signs and symptoms of a normal pregnancy. All pregnancies produce a hormone called human chorionic gonadotropin, or hCG, that is responsible for many of the symptoms experienced by women in early pregnancy and which can be measured by the means of a blood pregnancy test. Because you felt pregnant, had a positive pregnancy test, and your uterus was enlarging, both you and your doctor assumed that you had a normal pregnancy.

The most common indication that a problem exists is the onset of vaginal bleeding, frequently in the form of a brownish discharge that resembles prune-juice rather than blood. However, bleeding is seen quite commonly in early normal pregnancy and can have many other causes. The next most common sign is rapid enlargement of the uterus. Because there is no normal fetus present your doctor may be unable to find a fetal heart after 10-12 weeks. Less common symptoms you may experience are severe nausea and vomiting, symptoms related to high blood pressure, and symptoms related to abnormally high thyroid function. Once a molar pregnancy is suspected by a physician, the diagnosis can usually be confirmed by an ultrasound examination (sonogram), which is a sound wave picture of the uterine contents.