What is a Hydatidiform Mole?

A Hydatidiform Mole (Molar Pregnancy) occurs during fertilisation. There does not seem to be any definite reason why, although there are many theories.

A mole is made up of placental tissue that has grown dramatically more than normal, forming hydatid¹ or cysts.

There are two types of moles: -

• COMPLETE MOLE - A complete mole rarely has any foetal development, and if so, very little.

• INCOMPLETE (PARTIAL) MOLE - In this scenario, there is usually the presence of a foetus, umbilical cord etc. The foetus however will not usually last beyond the ninth week following the last menstrual period. A partial mole is less common than a complete mole.

What are the Chances?

Molar pregnancies are for unknown reasons more common in countries such as Japan, Korea, China and the Philippines, where the incidence is about 1 in 550 to 600 pregnancies. In the UK this drops to about 1 in 1000, and can drop as low as 1 in 2000 in the United States. In Russia however, it can be as high as 1 in 20.

Age can also increase the risk of developing a molar pregnancy. Pregnant women over the age of 50 stand 5 times more, or younger than 20, 1.5 times more of a chance of developing a mole.

A previous miscarriage doubles the chance of developing a mole, and a prior mole increases the risk by 30 times.

Symptoms

Vaginal Bleeding, larger than normal growth of the uterus, no foetal movement or tissue resembling a cluster of grapes passing from the vagina can all be an indication of a possible molar pregnancy.

Invasive Moles

Although a mole is normally benign, it can persist and invade the wall of the uterus.

Severe bleeding may occur should the mole penetrate through the thickness of the uterus. It can spread to other organs, usually the vagina and lungs.

A persistently elevated level of the pregnancy hormone, hCG², may be an indication that the mole has become invasive despite efforts to remove it.

Choriocarcinoma

Choriocarcinoma is a type of cancer which could develop after a molar pregnancy. A molar pregnancy however is not the sole cause for choriocarcinoma, it only increases the chance of it developing. It can spread throughout the body, but more commonly to the lungs, cervix, vagina, v***a, brain, liver, kidney and the gastrointestinal tract.

Gestational Trophoblastic Tumours (GTT)

GTT can follow both normal and abnormal pregnancies. The chance of developing GTT is 1000 times higher after a complete mole than a normal full term pregnancy.

The chance of GTT following a complete mole is approximately 8%, and following a partial mole, about 0.5%.

Tumours that do not respond to the drugs that have been administered, and have had to be removed surgically, are considered to be Choriocarcinoma's.

Placental Site Trophoblastic Tumours

These tumours are extremely rare, and unlike invasive moles, will usually not invade further than the wall of the uterus.

Treatment

The Doctor will perform a Dilation and Curettage
under general anesthesia.

As moles cause a dramatic increase in the hCG hormone level, blood tests will be performed regularly for up to, in some cases, 2 years after the mole has been removed to ensure that it has not regrown or invaded the wall of the uterus. An increase in these levels could also be an indication of choriocarcinoma.

In the case of an invasive mole or choriocarcinoma chemotherapy may be needed. Should this not be successful, a Hysterectomy could be performed.

Chemotherapy would be the normal treatment for GTT.

Placental Site Trophoblastic tumours are the least likely of these conditions to respond to chemotherapy, and will usually require a hysterectomy.

Future Pregnancies

Pregnancy is possible, even after an invasive mole or choriocarcinoma. It will however be required that you avoid falling
pregnant as long as the hCG levels are being monitored.