- Complete molar pregnancy. This happens when sperm fertilizes an egg that lacks complete genetic information. The tissue then grows as abnormal tissue, resembling a cluster of grapes as it fills the uterus.
- Partial molar pregnancy. This form of molar pregnancy occurs when two sperm fertilize an egg. The placenta becomes the molar growth, and any resulting fetal tissue develops severe defects.
The majority of molar pregnancies are not cancerous and are confined to the uterus. A more aggressive tumor in molar pregnancy cases is the chorioadenoma destruens. In this instance, the grape-like clusters grow into or through a muscle layer or the uterine wall. In about 15 percent of cases, the cluster will spread to tissues outside of the uterus.
All molar pregnancies, including choriocarcinoma, are more likely in women of Asian or African descent.
Molar Pregnancy Symptoms
Molar pregnancies resemble a normal pregnancy in its early stages. Missed periods and morning sickness may occur. But there are other symptoms that differentiate the molar pregnancy. These include vaginal bleeding, a larger-than-normal uterus, severe nausea and vomiting, and symptoms resembling hyperthyroidism, including a fast or irregular heartbeat, extreme tiredness, nervousness, and excessive sweating. Women may also experience an uncomfortable feeling in the pelvic area or vaginal discharge that has a grape-like shape.