Hydatidiform mole, or molar pregnancy, results from over-production of the tissue that is supposed to develop into the placenta. The placenta feeds the fetus during pregnancy. With a molar pregnancy, the tissues develop into an abnormal growth, called a mass.
There are two types:
Partial molar pregnancy: There is an abnormal placenta and some fetal development.
Complete molar pregnancy: There is an abnormal placenta but no fetus.
Both forms are due to problems during fertilization. The exact cause of fertilization problems is unknown. A diet low in protein, animal fat, and vitamin A may play a role.
Abnormal growth of the womb (uterus)
Excessive growth in about half of cases
Smaller-than-expected growth in about a third of cases
Nausea and vomiting that may be severe enough to require a hospital stay
Symptoms similar to preeclampsia that occur in the 1st trimester or early 2nd trimester -- this is almost always a sign of a hydatidiform mole, because preeclampsia is extremely rare this early in a normal pregnancy
If your doctor suspects a molar pregnancy, a suction curettage (D and C) may be performed.
A hysterectomy may be an option for older women who do not wish to become pregnant in the future.
After treatment, serum HCG level will be followed. It is important to avoid pregnancy and to use a reliable contraceptive for 6 - 12 months after treatment for a molar pregnancy. This allows for accurate testing to be sure that the abnormal tissue does not grow back. Women who get pregnant too soon after a molar pregnancy have a high risk of having another molar pregnancy.
More than 80% of hydatidiform moles are benign (noncancerous). Treatment is usually successful. Close follow-up by your doctor is important. After treatment, use effective contraception for at least 6 - 12 months to avoid pregnancy.
In some cases, hydatidiform moles develop into invasive moles. These can grow deep into the uterine wall and cause bleeding or other complications.
In a few cases, a hydatidiform mole develops into a choriocarcinoma. This is a fast-growing cancerous form of gestational trophoblastic disease.
Lung problems may occur after a D and C if the mother's uterus is larger than 16 weeks gestational size.
Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.