Gestational Trophoblastic Disease

Gestational Trophoblastic Disease (GTD) is an uncommon condition affecting approximately 1 in 1500 pregnancies. The condition develops due to an abnormal fertilisation event causing a tumour of placental (trophoblast) cells.

It comprises a range of conditions including Complete Hydatidiform Mole (CHM), Partial Hydatidiform Mole (PHM), Persistent Gestational Trophoblastic Neoplasia (GTN) (which can be non-metastatic or metastatic), Choriocarcinoma (CC) and Placental Site Trophoblastic Tumour (PSTT).

CHM results from an empty egg fertilising with one sperm which duplicates or with two sperm. No embryo is formed. PHM 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. Gestational Trophoblast Neoplasia (GTN) or persistent disease is a malignancy of placental cells that can occur after a molar or non-molar event.

Once you have been diagnosed with this condition you will be referred to the Queensland Trophoblast Centre for your condition to be monitored. Dr Andrea Garrett is Deputy Director of this service.

What Treatment is required?

Once you have had initial treatment for a non-viable pregnancy (usually a curettage or D&C) your pathology will be reviewed to ensure the correct diagnosis. Your Bhcg levels will then need to be monitored weekly. In 85% of patients, Bhcg levels will fall to normal and no further testing is required.

Persistent Disease

In approximately 15% of women, abnormal cells remain and continue to produce Bhcg. Your Bhcg levels will not return to normal and may in fact rise. In the event that this happens you will require additional treatment (see below).

You will need to have other tests performed (blood tests and imaging) and then receive a course of medication (chemotherapy) to destroy the remaining cells. You will be monitored closely during this process.

Follow Up

Once your Bhcg 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 PHM and 12 months for CHM. If you required a course of chemotherapy you will need to have a monthly blood test for 12 months.

Fertility

Once you have been diagnosed with GTD it is important that you do not fall pregnant until your follow up is complete. We recommend any form of contraception that you and your partner are comfortable with during that time. 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 Bhcg levels depending on your specific condition. There is no increased risk of congenital malformations in subsequent pregnancies.

Recurrence

The chance of this condition occurring again is approximately 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 Bhcg level will be performed to ensure it has returned to normal.

The Queensland Trophoblast Centre (QTC)

Queensland has been running a trophoblast registry since 1976. We have recently updated and expanded this service. QTC provides a registration and monitoring service for patients diagnosed with Gestational Trophoblastic Disease. We also provide a consultative service for patients and clinicians. We undertake research to a high ethical standard in order to improve our knowledge about the condition and improve patient outcomes and to provide expert care to our patients.