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QUADRUPLE TEST

The Quadruple Test | Pregnant woman
 

What is the quadruple test?

The quadruple test (known too as the quadruple screen test or quadruple blood test) is a screening test done in the second trimester of pregnancy between 14 and 20 weeks. The purpose of this screening test is to check your chances of having a baby born with Down's syndrome. This is unlike the combined screening test which also checks your chances of having a baby born with two other genetic conditions called Edward’s and Patau’s syndrome as well as Down’s syndrome.

The quadruple test for Down’s syndrome uses your age and the levels of four substances measured:

  • Beta-human chorionic gonadotrophin (made by the placenta)
  • Unconjugated estriol (made by the placenta and baby’s liver)
  • Alpha-fetoprotein (made by the baby)
  • Inhibin A (made by the placenta)

When is the quadruple test offered and do I have to take it?

The quadruple screening test is offered when you want screening but are too late for the combined screening  that is offered to women between 10 and 14 weeks. If you book your pregnancy too late for the combined test you will be offered the quadruple test. You can have the quadruple test between 14 and 20 weeks of pregnancy.

Also if your baby is lying in a position where the fluid at the back of the neck cannot be measured (the nuchal translucency scan) the combined test will not have been possible. In this situation you will be offered the quadruple test.

You don’t have to have the test—that decision is yours. Some parents would rather know the chances of their baby being affected by a condition so that they can prepare for future decisions, whereas others don’t want to know.

What are the risks of the quadruple test?

Because it’s a screening test and not invasive, the test is safe—there’s no risk of or other pregnancy complications. Waiting for test results can be an anxious time though.

How is the quadruple test done?

The quadruple test is performed with a simple blood test. The health professional taking your blood will insert a needle into your arm and take a sample that will be sent to a laboratory for analysis.

Time taken to receive your results can vary depending on where you live. Your midwife will tell you when you should expect to hear your results.

Is the quadruple test accurate?

The quadruple test is recognised as slightly less accurate than the combined test. It will identify around 75-80 of 100 babies who have Down’s syndrome compared to between 84-90 of 100 babies with the combined test.

How to interpret the results

As the quadruple test is just a screening test and not a diagnostic test, your quadruple test results won’t tell you for certain if your baby does or doesn’t have Down’s syndrome. Instead they will give you the chance—either higher chance or lower chance—that you might be carrying a baby with this condition.

You may get your results as a set of numbers that use a cut-off point of 150 for a higher chance result.

  • Higher chance: if your result is 1 in 150 or 1 out of a number less than 150 (e.g. 1 in 100) then your baby has a higher chance of having Down’s syndrome.
  • Lower chance: if your result is more than the cut-off value of 150 (e.g. 1 in 200) then your baby has a lower chance of having Down’s syndrome.

Out of 100 screening results, more than 95 will be lower chance and fewer than 5 will be higher chance. A lower chance result doesn't guarantee that your baby won't have Down’s syndrome. Likewise, a higher chance result doesn't guarantee that your baby will be born with the condition.

My quadruple test results are high risk, what are my options?

If your result is higher chance, you’ll have 3 options.

  1. You can be offered a diagnostic test, such as amniocentesis (needs linking). This can diagnose whether baby has a chromosomal condition but comes with a miscarriage risk of 1%.
  2. You can be offered a more accurate screening test called a Non-Invasive Prenatal Testing (NIPT). This is a more accurate screening test and can detect 99% of babies with down syndrome. It won’t give you a diagnosis but it carries no risks. You’ll still be offered a diagnostic test to confirm things if your NIPT result is positive.
  3. You can have no further testing.

 

Approved by ED Healthcare Team

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