The first screening test (combined or quad)

Introduction

If you choose to have the combined test, it will involve:

a blood sample taken from your arm between 10 and 14 weeks of pregnancy
an ultrasound scan measurement of fluid at the back of your baby’s neck between 11 and 14 weeks of pregnancy – this is known as the nuchal translucency (NT)

This information is combined with your age to work out the chance of your baby having the condition. If you are more than 14 weeks pregnant the combined test is not appropriate. You will instead be offered:

a blood test, called the quadruple test, between 14 and 20 weeks of pregnancy to screen for Down’s syndrome (this test is not as accurate as the combined test)
a 20-week scan to screen for Edwards’ syndrome and Patau’s syndrome

Safety of the test

The screening test cannot harm you or your baby but it is important to consider carefully whether or not to have this test.

The test cannot tell you if your baby definitely has one of these conditions. It can provide information that may lead to further decisions about your pregnancy.

If you receive a higher-chance result from the first screening test, you may need to decide whether to have a second screening test or a diagnostic test that has a risk of miscarriage. If you have a diagnostic test, depending on the result, you may need to decide whether to continue your pregnancy or to end the pregnancy.

Possible screening results

Depending on what you asked for when you decided to have the screening test, we will give you one or both of:

a result for Down’s syndrome
a joint result for Edwards’ syndrome and Patau’s syndrome

A lower-chance result means it is unlikely, though still possible, that your baby will have the condition. Most screening test results (around 97% of them) are lower chance.

A higher-chance result means it is more likely, but not certain, that your baby will have the condition. Overall, around 3% of screening test results are higher chance.

We will give each result as a chance, for example your baby has ‘1 chance in 150’ of being born with Down’s syndrome. The bigger the second number (such as 150), the smaller the chance your baby has of being born with the condition. So ‘1 chance in 200’ is smaller than ‘1 chance in 100’.

A ‘lower-chance’ result is 1 chance in 151 or more, for example 1 chance in 300. A ‘higher-chance’ result is 1 chance in up to 150, for example 1 chance in 100.

To understand what, for example, ‘1 chance in 300’ means, imagine a group of 300 women. One of these women will be pregnant with a baby that has the condition.

Not having the test

If you choose not to have the screening test for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome, the rest of your antenatal care will be unaffected.

Any scan during your pregnancy may pick up physical problems with your baby which could be related to these conditions. You will always be told if anything unexpected is found during a scan.

Getting my results

If your screening test shows a lower-chance result, you will be told within 2 weeks of the test being taken. If your screening test shows a higher-chance result, you will be told within a week of having the test. You will be offered an appointment to discuss:

the test results and what they mean
the condition your baby may have
the choices available to you

Further tests

If you have a lower-chance result you will not be offered a further test. If you have a higher-chance result, you may decide:

not to have any further testing
to have a second screening test (called NIPT) to obtain a more accurate screening result before choosing whether or not to have a diagnostic test
to have a diagnostic test straight away

Your decisions will be respected and health care professionals will support you. You should speak up if you feel your decisions are not being respected. Information is also available from support organisations. Whatever results you get from any of the screening or diagnostic tests, you will get support and care to help you decide what to do next.