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How molar pregnancy is diagnosed

In a molar pregnancy the fertilisation of the egg by the sperm goes wrong and creates abnormal cells or clusters of water filled sacs inside the womb. It can be diagnosed in different situations.

Diagnosis during routine pregnancy tests

When you are pregnant, the placenta produces a hormone called human chorionic gonadotrophin (hCG). It helps the baby to develop. It isn’t normally present in women who aren’t pregnant. The placenta releases hCG into your bloodstream and your body gets rid of the rest in your urine.

HCG is produced by a molar pregnancy and is at much higher levels than normal. So routine blood tests during pregnancy can pick up a molar pregnancy. 

Women usually have a routine ultrasound in the 12th week of their pregnancy. Molar pregnancies can show a characteristic 'snowstorm appearance' on the scan. There will also be no foetal tissue or only partial tissue. 

If your blood tests or ultrasound show a molar pregnancy, your midwife or doctor will tell you. This can be a shock and can be very upsetting. Your midwife can support you and let you know about counselling or organisations that can help you. 

The usual treatment is removal of the molar tissue from the womb. 

Bleeding or other symptoms during pregnancy

Your doctor or midwife might suspect you have a molar pregnancy if you have any of these symptoms during pregnancy: 

  • bleeding from the vagina that is dark and irregular
  • severe morning sickness
  • being big or small for your dates
  • tummy (abdominal) pain

If you have these symptoms see your GP or midwife. They will refer you to a specialist for tests. The tests usually include an abdominal ultrasound and blood tests to check your hCG levels.

Diagnosis after miscarriage or abortion

A doctor usually examines the placental and foetal tissue if you’ve had a miscarriage in hospital or an abortion. These checks can pick up the abnormal cells of a molar pregnancy. Your doctor or midwife will tell you if they see molar tissue. This can be a shock and can be very upsetting.

Your doctor or nurse can support you and let you know about counselling or organisations that can help you. 

You will need to have treatment to remove the molar tissue from the womb. 

Information and help