14 – 21 weeks.
The quadruple test is a screening for Down Syndrome and is usually performed if you have missed the nuchal scan earlier in your pregnancy.
It’s called the quadruple test because it measures four substances in your blood to calculate a Down Syndrome risk. The test is not invasive and does not harm you or your baby but it cannot be performed if you are an insulin dependent diabetic.
If you have already had either the nuchal scan or combined test and have received a high risk result we recommend that you consider a diagnostic test like a CVS or amniocentesis rather than having another screening test.
How accurate is the quadruple Down Syndrome test ?
Data has shown that in screening for Down Syndrome the quadruple test achieves a detection rate of nearly 80%. The detection rate is the number of babies with Down Syndrome predicted by a positive test. This means that 20% of women with pregnancies affected with Down Syndrome will receive a falsely reassuring screen negative result which is incorrect.
The test achieves the detection rate with a screen positive rate of 3% – this is the number of babies who did not have Down Syndrome but were considered high risk by the test. Therefore 97% of women whose pregnancies are not affected with Down Syndrome will receive a screen negative result.
What if I get a high risk result ?
If you are not reassured by the final risk estimation or you receive a high predicted risk – a one in 150 risk or lower – you can consider having either a CVS (chorion villus sampling) or amniocentesis test to give you a definite answer.