Molar pregnancies, otherwise known as Hydatidiform Moles, occur when a part of the baby that forms the placenta becomes quite abnormal. This can occur when a sperm penetrates an empty ovum (female’s egg) or when a couple of sperm enter an ovum. It occurs about 1 in 1000 to 2000 pregnancies. The mole can be complete, meaning there is no baby present, or partial where there is some part of the baby present. Women are more likely to have a molar pregnancy if they are in the extremes of their reproductive years (teens and 40’s). It also seems to be more common in Asians that live in Asia. The mole essentially resembles a bunch of grapes and contains fluid-filled sacks that grow rapidly. This results in the uterus growing larger than you would expect. The woman's body acts as if it is pregnant and even though there is no baby it sends excess blood to the uterus. The blood fills the uterus and can result in vaginal bleeding.
The diagnosis is usually made when an ultrasound is done following vaginal bleeding. Some other signs of a molar pregnancy can be severe nausea and vomiting, or early onset of high blood pressure. The uterus also many seem larger or sometimes smaller than it should be. When a molar pregnancy is diagnosed the uterus must be emptied using a surgical procedure under general anaesthetic (dilatation and curettage). Women with a molar pregnancy can develop a form of cancer. After a complete mole develops it can grow and invade the actual uterus in 15 percent of cases. Metastasis (rapidly spreading cancer) occurs in 4 percent of cases. This is not such a problem with partial moles. Despite these factors the rate of cure with chemotherapy is very high. Follow up is very important and women have frequent examinations and blood tests to watch for a rise in beta- HCG levels for at least one year. This is why it is important for these women to avoid pregnancy for one year following the molar pregnancy to avoid any confusion about the development of cancer. If a pregnancy were to occur, then an elevation in beta-HCG levels, which is normal in pregnancy, could not be differentiated from the disease process. Effective contraception should be used. Women with a prior complete or partial molar pregnancy have an increased risk of a second mole in a future pregnancy. All future pregnancies should have an early ultrasound to allow early detection of a second Molar pregnancy.