Early Pregnancy - Molar Pregnancy

Question 1

What are Gestational Trophoblastic Disorders?

Answer 1

A spectrum of disorders originating from the placental trophoblast that includes :-

1. A Complete Hydatidiform Mole.
2. A Partial Hydatidiform Mole.
3. A Choriocarcinoma.

Question 2

Which GTDs are pre-malignant? (2)

Which GTDs are malignant? (4)

Answer 2

Pre-Malignant : Partial and Complete Moles.

Malignant : Invasive Moles, Choriocarcinoma, Placental Trophoblastic Site Tumours, Epithelioid Trophoblastic Tumours.

Question 3

What is a Hydatidiform Mole?

Answer 3

A type of tumour that grows like a pregnancy inside the uterus.

Question 4

Aetiology of Hydatidiform Moles.

Answer 4

Conception causes an imbalance in the number of chromosomes.

Question 5

Pathophysiology of Complete Hydatidiform Mole (4).

Answer 5

1. An empty egg is fertilised by a single sperm cell.
2. The sperm cell duplicates its own DNA so all 46 chromosomes are of paternal origin.
3. There is no foetal tissue present - it is just a proliferation of swollen chorionic villi.
4. Rarely, it can be where 2 sperm cells fertilise an empty ovum (with no genetic material).

Question 6

Pathophysiology of Partial Hydatidiform Mole (3).

Answer 6

1. 2 sperm cells fertilise a normal ovum (with genetic material) simultaneously.
2. The new cell has 3 sets of chromosomes (triploidy).
3. It will divide and multiply into a tumour and some foetal material may form.

Question 7

Risk Factors of Molar Pregnancy (4).

Answer 7

1. Ends of Age of Fertility (i.e. under 16 and above 45).
2. Previous GTD.
3. Previous Miscarriage.
4. Use of OCP.

Question 8

MOLAR PREGNANCY vs. Normal Pregnancy (5).

Answer 8

1. More Severe Morning Sickness.
2. Vaginal Bleeding (in 1st/ early 2nd trimester)
3. Increased Enlargement of Uterus with Soft Boggy Consistency (excessive growth of trophoblasts and retained blood).
4. Abnormally high hCG.
5. Thyrotoxicosis.

Question 9

Aetiology of Thyrotoxicosis in Molar Pregnancy.

Answer 9

hCG can mimic TSH and stimulate thyroid hormone production (T3 and T4).

Question 10

Investigations of Molar Pregnancy (3).

Answer 10

1. Provisional Diagnosis - Pelvic Ultrasound : ‘Snowstorm Appearance’.
2. Confirmed Diagnosis - Histology of Mole after Evacuation (Central Heterogeneous Mass and Surrounding Multiple Cystic Areas/Vesicles).
3. Urine hCG and Blood hCG.

Question 11

Management of Molar Pregnancy (7).

Answer 11

1. Urgent Referral to Specialist Centre for Evacuation of Uterus (Suction Curettage)
2. Products of Conception are sent for histological examination to confirm diagnosis.
3. hCG levels are monitored until they return to normal every 2 weeks. Complete - for at least 6 months; Partial - 4 weeks later.
4. Effective contraception is recommended to avoid pregnancy in next 12 months.
5. Medical Evacuation with Oxytocic Agents (Greater Gestation with Foetal Development and not Conductive to Surgical Evacuation).
6. Anti-D Prophylaxis if mother is Rhesus Negative.
7. Chemotherapy if hCG does not fall.

Question 12

Malignancy of Moles.

Answer 12

Usually benign but if they invade the uterine myometrium, they can disseminate around the body to become invasive moles and so will require systemic chemotherapy.

Question 13

Choriocarcinoma (Definition and Epidemiology).

Answer 13

Definition : Choriocarcinoma is a malignancy of the trophoblastic cells of the placenta and characteristically metastasise to the lungs.

Epidemiology : 2-3% go on to develop into Choriocarcinoma.

Question 14

Placental Site Trophoblastic Tumours (Definition).

Answer 14

Malignancy of the Intermediate Trophoblasts which are normally responsible for anchoring the placenta to the uterus.

Question 15

Epithelioid Trophoblastic Tumours (Definition).

Answer 15

Malignancy of the Trophoblastic Placental Cells which can be very difficult to distinguish from Choriocarcinoma and mimics the cytological features of SCC.