Screening for Down’s, Edwards’ and Patau’s syndromes: the combined test

Screening for Down’s, Edwards’ and Patau’s syndromes is offered to everyone, and it is your choice. Here’s what the combined test involves, when it happens and how you get your results.

What is it?

The NHS offers screening for these conditions when you are between 10 and 20 weeks pregnant. Screening tells you the chance of your baby having a condition. It can’t tell you for certain, and it doesn’t diagnose anything.

It’s your choice

You can choose screening for all three conditions, for Down’s syndrome only, for Edwards’ and Patau’s only, or for none. Your midwife will talk through the options, and you can ask any questions before deciding. Some people feel strongly that they want to know. Others would rather not, and that’s fine too.

The combined test

The NHS says the combined test is usually done between 10 and 14 weeks. It has two parts:

a blood test, taken from your arm
an ultrasound measurement of the fluid at the back of your baby’s neck (the nuchal translucency), taken at your 12-week scan

The two parts are usually done together but can be done separately. The NHS says there are no known risks to you or your baby from an ultrasound scan.

If you’re past 14 weeks

If you are beyond 14 weeks, you can have a blood test between 14 and 20 weeks, called the quadruple (quad) test. The NHS says it checks for Down’s syndrome but is not as accurate as the combined test. Edwards’ and Patau’s syndromes are also checked for at the 20-week scan, if you choose to have it.

Getting your results

The NHS says you should get your results within 2 weeks. A lower chance result comes by letter and includes a figure, such as 1 chance in 300. If you get a higher chance result, you’ll be contacted by phone or in person within a week. If you haven’t heard anything after 2 weeks, contact your midwife. Down’s syndrome gets its own result. Edwards’ and Patau’s syndromes get a joint result.

What the results mean

Lower chance. Most people get this result. No further tests are offered.
Higher chance. This does not mean your baby definitely has the condition. The NHS says most people with a higher chance result have a baby without any of the conditions. You’ll be offered an appointment to talk about your options. See what a higher chance result means.

The cut-off for a higher chance result is set by each hospital. ARC says it is usually 1 in 150.

Differences across the UK

This page mainly describes the NHS in England. ARC says the combined test is not available on the NHS in Northern Ireland, where you can ask for the quadruple test, which only screens for Down’s syndrome. Scotland and Wales run their own screening programmes, so ask your midwife what is offered where you live.

Antenatal Results and Choices (ARC) offers free, non-directive information and support. Its helpline is 020 7713 7486, Monday to Friday, 10am to 5.30pm, with calls on Tuesday and Thursday evenings (8pm to 10pm) arranged by emailing info@arc-uk.org. You can also text 07908 683004 (UK only).

Questions people ask

Is the combined test a diagnosis?

No. It gives a chance, not an answer. Only a diagnostic test (CVS or amniocentesis) can tell you for certain.

What if I say no to screening?

That’s your right, and your care continues as normal. You can change your mind later, though some tests have a time window.

Can I have a different, more accurate test?

After a higher chance result, you can be offered a blood test called NIPT. See NIPT.

Does screening check for other conditions?

The combined test is for Down’s, Edwards’ and Patau’s syndromes. The 20-week scan looks for other physical conditions.