Molar pregnancy

Diagnosing a molar pregnancy

1. Ultrasound scanning enables early diagnosis of molar pregnancy – especially in the case of a complete mole. Incomplete moles can be more difficult to identify if some parts of the foetus are present – if there is any uncertainty a repeat scan will be arranged.

In a Twin pregnancy where one is a partial molar pregnancy, the pregnancy is usually allowed to go ahead. It can also proceed if there’s a complete mole alongside a normal pregnancy, but couples will be counselled about the risks involved:

• reduced live birth rate of 25%
• risk of haemorrhage or pre-eclampsia
• subsequent need for chemotherapy in about 20% of cases

2. Laboratory examination and testing after a miscarriage, termination or an ectopic pregnancy, the placenta is always examined by a pathologist. In molar pregnancies the abnormal overgrowth of the placenta leads to excessive production of the pregnancy hormone human Chorionic Gonadotrophin (hCG). A simple blood or urine sample can determine levels of hCG, and:

• help to diagnose a molar pregnancy
• indicate when the disease is cured – as it improves, levels fall, and when there’s no disease in the body, the level of hCG in the blood or urine is virtually zero

Treating a molar pregnancy

Dilatation and Curettage (D&C or ‘scrape’) is carried out to remove as much of the placenta from the womb as possible. It may be necessary to repeat this procedure because even a tiny amount of mole left in the body can grow and spread. In the majority of cases this operation does cure the disease. Chemotherapy will be necessary in about 6-10% of cases with the following symptoms:

• hCG levels have risen for two weeks or more
• examination of tissue has shown choriocarcinoma
• the disease has spread to other areas
• hCG levels have increased after a normal value