Gestational trophoblastic disease (molar pregnancy)

Gestational trophoblastic disease is a condition whereby trophoblastic tissue (the tissue that grows to form the majority of the placenta) proliferates in a pregnant, or recently pregnant, woman. These growths are considered tumours.

Gestational trophoblastic disease can occur after a normal or ectopic pregnancy. If this condition occurs during a pregnancy, it can cause miscarriage, eclampsia or foetal death. Tumours can be benign or malignant. Molar pregnancies do not interfere with fertility.

Signs and symptoms of gestational trophoblastic disease

• Positive pregnancy test
• Enlarged uterus/wrong size uterus for dates
• Vomiting
• Vaginal bleeding
• Preeclampsia (particularly during early pregnancy)
• Grape-like tissue coming out of the vagina
• Masses, cysts
• Absence of foetus
• Unexplained cancers
• Unexplained pregnancy complications

Classification of gestational trophoblastic disease

1. Hydatidiform mole
2. Chorioadenoma destruens (invasive mole)
3. Choriocarcinoma (malignant cells, typically after a hydatidiform mole)
4. Placental site trophoblastic tumour (rare)

Hydatidiform moles

A molar pregnancy is an abnormal pregnancy, with the hydatidiform classification the process of villi becoming hydropic and trophoblastic tissue proliferating. This type of mole is most common between the ages of 17 and 35 in women who have had a molar pregnancy previously.

In the United States, this is about one in every 2,000 gestations, but in Asian countries, numbers are about one in every 200 gestations. Most hydatidiform moles are benign, but can become invasive. Up to three per cent of hydatidiform moles are followed by the cancer form of a mole, the choriocarcinoma.

The uterus may become larger than expected within 10-16 weeks gestation. Women test positive for pregnancy, but have vaginal bleeding and severe vomiting. There is no foetal heartbeat or movement. Complications can include shock and infection.

Chorioadenoma destruens (invasive mole)

An invasive mole means the myometrium is invaded by a hydatidiform mole.

Choriocarcinoma

Choriocarcinomas are invasive and malignant tumours, lacking in hydropic villi. Typically appears after a hydatidiform mole.

Placental site trophoblastic tumor

These tumours are very rare, and is where trophoblastic cells persist after a pregnancy. This can invade nearby tissues or become malignant. This form of mole tends to bleed.

Treatment of molar pregnancies

Treatment includes removing the mass by suction, using a curette (the same process that is used during medical abortions to empty the uterus). Chemotherapy may be indicated and birth control may be necessary. In some cases, a hysterectomy may be performed.