We need to have accurate dating of your pregnancy so if you come before your first scan then please book a harmony test with scan so that a scan for viability & dating will be done followed by your blood test. We will see you to discuss the pros and cons of testing and take your consent if you decide to go ahead. A low risk result obviously does not guarantee a healthy baby. Non-invasive prenatal testing does not diagnose other genetic or structural diseases such as spina bifida.
Some couples will receive a high chance result and then proceed to an invasive test. Many who opt for an NIPT as the next step will be reassured by a low chance result. Invasive tests are reported to have a 1 in 200 risk of miscarriage. NIPT is another option as an additional step prior to invasive testing. In many cases the baby will not have Down’s syndrome. Many couples now choose to pay for a non-invasive prenatal test (NIPT) such as Harmony because of its high sensitivity for Down’s syndrome.Īnother reason for choosing an NIPT is after receiving a high chance result for Down’s syndrome from the 12 week NHS screening test. The Harmony test is available early in the pregnancy, from 10 weeks onwards. The PPV of the test is 37% for Edward’s syndrome and 49% for Patau’s syndrome. The reported sensitivity for these is 97% (T18) and 94% (T13), meaning that for Edward’s syndrome, approximately 3% of babies who have the condition will not be detected on Harmony testing and for Patau’s 6% of babies who have the condition will not be detected with the Harmony test. This means it is less possible to be certain of test performance. Test performance for Edward’s and Patau’s SyndromesĮdward’s syndrome (trisomy 18) and Patau’s syndrome (trisomy 13) are rarer conditions. Therefore for high chance harmony test results an invasive test such as amniocentesis or chorionic villus sampling is recommended to give diagnostic results. One large study reported the PPV for low risk women to be 82% for Down’s syndrome. If you are low risk the positive predictive value will be much lower, again the risk depends on factors such as your age. If you have had a high chance result for Down’s syndrome from an NHS screening test or are in an older age group the positive predictive value will be above 90%.
The PPV depends upon the background risk. This is the likelihood that a result stating a high chance that the baby has the condition, is correct. This means that the harmony test will pick up more than 99% of babies who have Down’s syndrome.īecause the sensitivity is not 100% there is a small chance (less than 1%) that a harmony test may report a low probability of the baby being affected when in fact the baby does have the condition.Īnother aspect of test performance is its “positive predictive value” (PPV). This screening test has a high “sensitivity” for Down’s syndrome (Trisomy 21) of over 99%.
You can have a Harmony test at Somerset Early Scans from 10 weeks of pregnancy onwards. The test looks at DNA from the baby that is present in the mothers bloodstream. In these conditions there are 3 copies of certain chromosomes instead of 2 (“Trisomy”). The Harmony test is a blood test that looks for whether your baby has Down’s Syndrome, Edward’s or Patau’s Syndrome. Harmony – Book Now £419 / £459 with ultrasound scan Non invasive prenatal testing
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