A choriocarcinoma is a type of cancer that develops from the placenta. It occurs in about 1in every 30,000 pregnancies.

Choriocarcinomas may develop as a complication of something called a 'molar pregnancy'. A molar pregnancy happens when, after fertilisation of the female egg by the male sperm, only the placenta develops, without any trace of an embryo, or unborn child. The mass of placenta goes on to form a growth within the womb. This growth is called a hydatidiform mole, hence the name 'molar pregnancy'.

There is a special blood test that helps to diagnose choriocarcinoma. This checks on the blood level of a hormone called human chorionic gonadotrophin (hCG). This hormone is produced by the placenta during a normal pregnancy but abnormally high levels appear in women who have choriocarcinoma.

Any woman who has a hydatidiform mole will usually have regular check-ups afterwards when blood tests are taken to measure the hCG level. If the hCG levels remain abnormal, then this might suggest that there is a choriocarcinoma. The next step would be to do an ultrasound scan of the womb which would show if there were signs of a tumour. If the ultrasound was abnormal then a small operation, called a D&C, would be done to take away the abnormal tissue in the womb. Usually a D&C involves scraping the lining of the womb to remove tissue, but in the case of suspected choriocarcinomas tissue is sucked out of the womb with a special vacuum pump to avoid the risk of damaging the lining of the womb. The D&C is done under anaesthetic but does not involve any cutting or stitches. Examination of the tissue in the laboratory would then confirm the diagnosis.

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