A molar pregnancy can put a patient at risk for malignancy, specifically gestational trophoblastic neoplasia (GTN).
Risk of malignancy
- Complete molar pregnancy: Women diagnosed with complete hydatidiform molar pregnancy are at a 15% to 28% risk of developing persistent GTN requiring further management with chemotherapy
- Partial molar pregnancy: The risk of GTN is significantly lower in partial molar pregnancies compared to complete molar pregnancies
- Post-evacuation hCG levels: The risk of developing persistent GTN is associated with post-evacuation human chorionic gonadotropin (hCG) levels. Women whose hCG levels decline below 50 mIU/mL during their follow-up have no more than a 1.1% risk of developing persistent GTN
Prophylactic chemotherapy
- Prophylactic chemotherapy (P-Chem) may reduce the risk of GTN in women with a hydatidiform mole. However, the administration of P-Chem before or after evacuation of a hydatidiform mole to prevent malignant sequelae remains controversial, as the risks and benefits of this practice are unclear
Follow-up and surveillance
- Patients undergoing removal of a molar pregnancy are advised not to become pregnant until they have completed their hCG follow-up
- The Royal College of Obstetricians and Gynaecologists (RCOG) 2021 guidelines recommend counseling patients with a twin pregnancy where there is one viable fetus and the other pregnancy is molar, about the potential increased risk of perinatal morbidity and the outcome for GTN
While a molar pregnancy does increase the risk of malignancy, the risk varies according to the type of molar pregnancy and post-evacuation hCG levels. Prophylactic chemotherapy and careful follow-up can help manage this risk.