The SAFE Test, Panorama and Harmony Non Invasive Prenatal Tests
The aim of the SAFE Test, Panorama and Harmony Tests are to establish whether the unborn baby is affected with a chromosomal abnormality such as Down's syndrome, but without having to risk a miscarriage with an invasive sample such as CVS or amniocentesis.
The tests are aimed at detecting Down's syndrome (trisomy 21), but also gives information for two other fetal chromosomal abnormalities (trisomy 18, Edwards syndrome; and trisomy 13, Patau's syndrome).
They do this by analysing fetal cell-free DNA circulating in the maternal blood. Because the test is non-invasive there is no risk for miscarriage or other risks associated with invasive testing procedures.
Who can get Down's syndrome?
The vast majority of babies are normal. However all women, whatever their age, have a small risk of delivering a baby with a physical and/or mental handicap. In some cases the handicap is due to chromosomal abnormality such as Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome).
What is the risk for Down's syndrome?
The risk of these conditions increases as the mother's age increases. However, the risk can be more accurately assessed (called screening) at 11-13+6 weeks based on measurement of the nuchal translucency (a small collection of fluid behind the neck of the baby), together with knowledge of the mother's age and measurement of the maternal hormones beta HCG and PAPP-A. Mothers with a high predicted risk may then decide if they wish to have further testing.
How do we check for Down's syndrome?
The only way to know for sure whether or not the fetus has a chromosomal abnormality is by having an invasive prenatal diagnosis test such as chorionic villus sampling (CVS) at 11-15 weeks or amniocentesis at 16 weeks or later. However, these tests involve the introduction of a needle into the uterus to take a sample of the placenta (CVS) or amniotic fluid (amniocentesis) and this carries a risk of miscarriage of about 1%.
What is non-invasive prenatal testing?
With the SAFE Test, Panorama or Harmony Test cell-free fetal DNA circulating in maternal blood is analysed. As this is done by a simple blood test there is no significant risk to you or the baby. Non invasive prenatal testing can be considered a very accurate screening test.
This is because:
- If the test shows that there is a low risk that the fetus has Down's syndrome, it is very unlikely (<1:10,000 risk) that the fetus will be abnormal.
- The test identifies more than 99%, but not all, of the fetuses with Down's syndrome, 98% with Trisomy 18 and 80% of with Trisomy 13.
- If it shows that there is a high risk that the fetus has an abnormality, it does not mean that the fetus definitely has one of these defects. Further testing is usually required by performing CVS or amniocentesis.
Even when mothers decide to have an invasive prenatal diagnostic test or a non-invasive prenatal test, a scan is still recommended as it can exclude other problems.
How does it work?
In Down's syndrome and other trisomies, there are three rather than two of a particular chromosome. These trisomies can be detected by measuring the DNA from the fetus that is found in the mother's blood stream (called cell-free fetal DNA). Although only about 10-15% of the cell-free DNA circulating in maternal blood is from the fetus, it can be detected and measured. Differences in chromosome fragments in maternal blood can be used to detect fetuses affected with Down syndrome and a few other trisomies.
Who cannot have the SAFE Test, Panorama or Harmony Test?
The SAFE Test, Panorama or Harmony Test can be performed in most pregnancies of at least 10 weeks gestational age. However the test is not currently available in egg donor pregnancies of multiple fetuses where the egg donor is unrelated to the recipient and or for detection of partial trisomies.
How much does it cost?
| SAFE Test | From 10 weeks (Blood Test only) | £345 |
| SAFE Test | Plus Early Viability Scan £395 | Plus Early Anomaly Scan £495 |
| Panorama® | Plus Early Viabilty Scan £450 | Plus Early Anomaly Scan £550 |
| Harmony™ | Plus Early Viabilty Scan £450 | Plus Early Anomaly Scan £550 |
* Prices quoted include a pregnancy ultrasound scan