Different types of Down syndrome tests are available at different points in your pregnancy. You should think carefully about when will be the best time to have these tests as some can only be performed within a limited timeframe. You will only be able to confirm the results if you can have amniocentesis or CVS. The timing will also determine what options you have if your baby does have Down’s syndrome and you are thinking about ending the pregnancy.
The nuchal scan is the most common Down syndrome test, but it can only be performed within a very strict timeframe.
- Nuchal translucency tests can be performed between 11 weeks 5 days and 13 weeks 5 days
- The results will be available the same day and a consultant will be there to provide advice if your baby is found to be at higher risk of Down’s syndrome
Non-invasive prenatal testing is available over a much longer period although it is most often performed just after the nuchal scan. Many parents choose NIPT because the ultrasound suggested a higher risk of Down‘s syndrome
. However, the earliest NIPT tests can be performed before the nuchal scan. You can have NIPT from 9 weeks and you can then at any point during the rest of your pregnancy.
How long you have to wait for the results of NIPT will depend on the type of test you have chosen:
- Harmony test results should be back in 3-7 days
- Panorama test results will be available in 9-14 days
- SAFE test results will take 3-7 days
Amniocentesis and Chorionic Villus Sampling (CVS)
The nuchal scan and NIPT are screening tests for Down’s syndrome, so they can only tell you whether your baby is likely to be affected. Although 99 out of 100 babies with Down’s syndrome will be correctly identified by NIPT and the risk of a false positive is very low, you will still be advised to have a diagnostic Down syndrome test to confirm the result.
- Chorionic Villus Sampling (CVS) can be performed between 11 and 14 weeks
- Amniocentesis is usually performed between 15 and 20 weeks