Serenity Prenatal Test
See our FAQs for more information
Serenity Test: Information
* The pregnancy must be over 10 weeks gestation otherwise the blood test will not be performed.
With the advances in genetic medicine cell free foetal DNA which is present in the mother’s blood from early pregnancy, can now be used to sequence the DNA of the baby to check for genetic abnormalities. This is as simple as taking a blood sample from the mother and it being sent away for lab testing. This is huge leap in genetics testing as this test only requires a simple non invasive blood sample from the mother.
The Serenity test includes an ultrasound which is performed prior to the bloods being taken. The purpose of the scan is to date the pregnancy, check that it is a viable pregnancy and also check for the presence of two or more foetuses.
The serenity test uses verifi® technology which uses ‘full genome sequencing’ to count the number of copies of foetal chromosomes in the mothers blood, it then calculates the risk of there being too many or too few copies of chromosome 13, 18 & 21 in the foetus. This test has been shown to be the most sensitive non-invasive screening test available.
With Serenity there is the option to test for abnormalities of the sex chromosomes, there is normally 2 sex chromosomes either XX – female or XY – male. However abnormalities arise when you receive 1,3, or even 4 chromosomes. Monosomy X is where you only receive one X chromosome, this is also know as Turners Syndrome. Trisomy of the sex chromosomes is where you receive three chromosomes either XXX (Triple X syndrome) or XXY also know as Klienfelters syndrome. It is also possible to receive 4 sex chromosomes XXYY.
The Serenity test also has the option of testing for microdeletions, a microdeletion is where a small section of the genetic information on the chromosome is lost during the process of DNA replication. The size and position of the deletion will determine which clinical features are manifested and also the severity of the feature. The serenity test will quantify the risk of the foetus having 22q11 deletion (DiGeorge region),15q11 deletion (Angelman/ Prader-Wili) 1p36 deletion, 4p (Wolf-Hirschorn) 5p (Cri-du Chat.)
For more information on the Serenity test see our Frequently Asked Questions Page.
Conventional Down’s Syndrome Test
The current NHS screening tests for Down’s syndrome are the “Combined test” or the “quadruple test”. The combined test is carried out between 11 and 14 weeks, which involves a Nuchal Translucency scan and blood test. The Nuchal Translucency scan measures the length of the nuchal fluid at the nape of baby’s neck, the greater the extent of the nuchal pad the greater the risk of abnormality. The blood test measures serum markers in the blood; these are then used along with factors such as maternal age, weight, family origin and gestation of the pregnancy to determine the risk of having a Down’s syndrome baby.
The quadruple test is carried out if you are too far on in pregnancy to have the combined test, this test is a blood test with looks for markers in your blood these markers are used along with maternal age, weight and gestational age to calculate your risk factor of having a down’s Syndrome baby. This is either low risk or high risk. High risk patients will be invited for a diagnostic test such as chronic villus sampling (CVS) or amniocentesis which both come with a risk of miscarriage. There is a 5% false positive rate with these conventional tests, which is much higher than the false positive of the Serenity test which is less than 1%, which means with harmony there is less chance of having to have a follow up invasive procedure.
See our FAQs page for further information.