Gestational Trophoblastic Disease (GTD) is a rare condition affecting approximately 1 in 1500 pregnancies. It is a disease in which abnormal cells grow in the tissues that are formed following conception (the joining of sperm and egg). It comprises a range of conditions including Complete and Partial Hydatidiform Mole, Persistent Gestational Trophoblastic Neoplasia, Choriocarcinoma and Placental Site Trophoblastic Tumour.
Complete Mole results from an empty egg fertilising with one sperm which duplicates or with two sperm without the development of an embryo. The tissue that is formed resembles grape-like cysts. Partial Mole results from a normal egg fertilising with one sperm which duplicates or with two sperm. An extra set of chromosomes is present. An embryo may or may not develop but this will not continue as a normal pregnancy. Persistent Gestational Trophoblast Neoplasia is a malignancy of placental cells that can occur after a molar or non-molar event.
Patients with this condition need to be followed up closely with βhcg levels. In 85% of patients, βhcg levels will fall to normal and no further testing is required. In the other 15%, abnormal cells remain and continue to produce βhcg so the levels will stay elevated. Patients will then require additional treatment which is in the form of chemotherapy.
Follow-up after Gestational Trophoblastic Disease
Once your weekly βhcg falls to normal you will require a varying degree of follow up. After 3 consecutive negative Bhcg levels, you will need to have a monthly blood test for up to 6 months for Partial Mole and 12 months for Complete Mole. If you required a course of chemotherapy you will need to have a monthly blood test for 12 months.
It is important that you do not fall pregnant until your follow up is complete. Contraception is recommended. You will be notified when you are able to pursue further pregnancies – this may vary from 6 months up to 12 months following normalization of βhcg levels depending on your specific condition. There is no increased risk of congenital malformations in subsequent pregnancies, even after the chemotherapy treatment.
Recurrence of Gestational Trophoblastic Disease
The risk of this condition recurring is about 1%. When you do fall pregnant again we advise that you have an early Ultrasound to establish the presence of a viable pregnancy. No special precautions need to be taken during the pregnancy. Six weeks after your baby is delivered a βhcg level will be performed to ensure it has returned to normal.