Complications

After a molar pregnancy has been removed, molar tissue may remain and continue to grow. This is called persistent gestational trophoblastic neoplasia (GTN). This occurs in about 15% to 20% of complete molar pregnancies, and up to 5% of partial molar pregnancies.

One sign of persistent GTN is a high level of human chorionic gonadotropin (HCG) — a pregnancy hormone — after the molar pregnancy has been removed. In some cases, an invasive hydatidiform mole penetrates deep into the middle layer of the uterine wall, which causes vaginal bleeding.

Persistent GTN can nearly always be successfully treated, most often with chemotherapy. Another treatment option is removal of the uterus (hysterectomy).

Rarely, a cancerous form of GTN known as choriocarcinoma develops and spreads to other organs. Choriocarcinoma is usually successfully treated with multiple cancer drugs. A complete molar pregnancy is more likely to have this complication than a partial molar pregnancy.