11 weeks & 2 days of pregnancy to 13 weeks
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What is the Integrated Down Syndrome Test?
When can I have the Integrated Down Syndrome Test?
How does the Integrated Down Dyndrome Test work?
What do the two blood tests do?
Why should I wait until the second stage to receive a result?
How accurate is the Integrated Down Syndrome Test?
Can other abnormalities be identified by the Integrated Test?
What is meant by a Screen-Positive result?
How do I book an Integrated Down Syndrome Test?
Where can I read more about the Integrated Down Syndrome Test?
What is my next scan after the Integrated Test?
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What is the Integrated Down Syndrome Test?
The Integrated Test is an alternative screening test for Down Syndrome to the Nuchal Scan.
This test blends the results of a first trimester scan and blood test together with a second trimester blood test to give a single risk estimate.
The Integrated Test has been developed by Professor Wald and his team at The Wolfson Institute, St Bartholomew’s Hospital, London. Professor Wald is a pioneer of Down Syndrome screening in the UK. He and the Wolfson Institute are internationally recognised for their work in this area. For this service The London Ultrasound Centre provide the scanning expertise and the blood samples are analysed by The Wolfson Institute.
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When can I have the Integrated Down Syndrome Test?
The test is perfomed in two stages.
The first stage of the test is performed in the first trimester no earlier than 11 weeks & 2 days of pregnancy and up to 13 weeks gestation, as determined by the first day of your last menstrual period (LMP) or a previous dating scan.
The second stage of the test is performed in the second trimester at 15 or 16 weeks of pregnancy. Up to 22 weeks is also possible.
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How does the Integrated Down Dyndrome Test work?
In the first stage a scan is performed from 11/2 - 13 weeks gestation to measure the size of the baby, its nuchal translucency thickness (NT - the space at the back of your baby's neck) and to check for the presence or absence of a nasal bone. A blood test is also taken at this time for later analysis.
A second blood test is taken from 15 - 16 weeks and a follow up scan is offered as reassurance and to confirm all is progressing well.
The data from your first ultrasound scan and results from both blood tests are integrated to produce a final screening result three days after your final blood sample.
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What do the two blood tests do?
The first blood test is used to measure your concentration of PAPP-A.
The second blood test is used to measure your concentration of:
- AFP
- Free Beta HCG
- Inhibin-A
- Unconjugated Estriol
The final screening result blends the visibility of the NT measurement, presence or absence of a nasal bone in the scan, plus the levels of the five markers in your blood, together with your age, to estimate your risk of a having a Down syndrome pregnancy.
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Why should I wait until the second stage to receive a result?
By using data obtained in early and later in pregnancy the detection rate becomes greater than most first trimester Down Syndrome screening tests.
The Integrated Test will distinguish affected from unaffected pregnancies more accurately, reducing the chance that a Down Syndrome pregnancy is missed as well as reducing the chance that you will need an invasive diagnostic test, such as an Amniocentesis or CVS.
However, the greater accuracy achieved by waiting until after 15 weeks for a result is not acceptable to some parents who for many reasons may want their Down Syndrome screening risk to be given as early as possible. In this case parents should opt for the Nuchal Scan.
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How accurate is the Integrated Down Syndrome Test?
Data from the Wolfson Institute has shown that in screening for Down Syndrome, the Integrated Test with nasal bone achieves a detection rate of 97%. (A detection rate is the number of babies with Down Syndrome predicted by a positive test.) Note that this means 3% of women with pregnancies affected with Down's syndrome will receive a (falsly reassuring) screen-negative result.
The test achieves the high detection rate with a low screen positive rate of 1%, that is the number of babies who did not have Down’s Syndrome but were considered high risk by the test. Therefore 99% of women whose pregnancies are not affected with Down's syndrome will receive a screen-negative result.
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Can other abnormalities be identified by the Integrated Test?
Yes. The Integrated Test also indentifies babies with a high risk of Edward's Syndrome.
A high AFP level from the second blood test may also alert the sonographer to look even more carefully for Spina Bifida at the 18-20 week anomaly scan but will not positively identify Spina Bifida.
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What is meant by a Screen-Positive result?
A Screen-Positive indication will be given where the result of your Integrated Down Syndrome test has passed a certain threshold.
The UK National Screening Committee has defined a 1:150 risk at birth as the screen-positive level for the Integrated Test.
If your result is 1:150 or higher risk you will be offered a diagnostic test, in this case an Amniocentesis.
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How do I book an Integrated Down Syndrome Test?
For prices and to make a booking please see our online booking website.
The blood tests are done at the The Doctors Laboratory Patient Reception. We will provide a sampling request forms either at your first appointment or at your second follow up scan appointment.
The results of the test will usually be available 2 -3 days after the second blood sample is taken. We will call you with your result and email or mail the final report.
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Where can I read more about the Integrated Down Syndrome Test?
For copies of the Integrated Test information leaflets please click on the links below.
The documents are provided in PDF format.
The Integrated Test | Questions
and Answers
The Intergrated Test | Information for Healthcare Professionals
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What is my next scan after the Integrated Test?
The next scan you should expect in your pregnancy after the Integrated Test is the 20 Week Anomaly Scan.
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