Gestational Trophoblastic Disease

Question 1

What is a ‘molar pregnancy’?

Answer 1

Abnormal form of pregnancy in which a non-viable fertilized egg implants in the uterus and will fail to come to term

A molar pregnancy is a gestational trophoblastic disease which grows into a mass in the uterus that has swollen chorionic villi

These villi grow in clusters that resemble grapes

Question 2

Define Gestational trophoblastic disease (GTD)

Answer 2

Term used to describe a group of pregnancy-related tumours:

1) Pre-malignant conditions (more common) = such as partial molar pregnancy (egg/2 sperm) and complete molar pregnancy (empty egg/1 sperm).
2) Malignant conditions (rarer) = such as invasive mole, choriocarcinoma, placental trophoblastic site tumour and epithelioid trophoblastic tumour.

Question 3

Outline the pathophysiology of a molar pregnancy

Answer 3

Partial = one ovum with 23 chromosomes is fertilised by two sperm, each with 23 chromosomes. This produces cells with 69 chromosomes (triploidy)

Complete = one ovum without any chromosomes is fertilised by one sperm which duplicates, or (less commonly) two different sperm. This leads to 46 chromosomes of paternal origin alone

*** these tumours are usually benign but can become malignant

Question 4

Outline the Types of Gestational Trophoblastic Disease

Answer 4

Molar Pregnancy

Choriocarcinoma = malignancy of the trophoblastic cells of the placenta

Placental site trophoblastic tumour = malignancy of the intermediate trophoblasts, which are normally responsible for anchoring the placenta to the uterus

Epithelioid trophoblastic tumour = malignancy of the trophoblastic placental cells

Question 5

What are the clinical features of Gestational trophoblastic disease?

Answer 5

Asymptomatic - USS detected

Vaginal bleeding

Abdominal pain

Hyperemesis (increased titre of B-hCG which is thought to be linked to nausea in pregnancy)

Hyperthyroidism (gestational thyrotoxicosis due to stimulation of the thyroid by high HCG levels)

Anaemia

Question 6

How is suspected Gestational trophoblastic disease investigated?

Answer 6

Urine B-hCG

Blood B-hCG levels

US (complete mole has a granular or snowstorm appearance with a central heterogeneous mass and surrounding multiple cystic areas/vesicles)

Histological examination of the POC

Mets = MRI, CT TAP

Question 7

How is Gestational trophoblastic disease best managed?

Answer 7

Register with a GTD centre for follow-up and monitoring in future pregnancies

Molar preg = suction curettage, medical evacuation, anti-D prophylaxis consideration, chemo

Malignant = surgery, chemo