Professor Cameron has a weekly clinic at GCRM on Tuesdays from 9.30am.
Appointments with Julie Hamilton Diagnostic Radiography, Pg Dip Medical Imaging Ultrasound, available in Edinburgh.
Non Invasive Prenatal Testing/ Screening (NIPT/NIPS)
Non Invasive Prenatal Testing is currently the most advanced non-invasive pregnancy screening available for parents who would like to determine if they have a low probability or high probability for their baby having the conditions Down’s syndrome, Edwards’ syndrome or Patau’s syndrome. NIPT is available from as early as 10 weeks of pregnancy, for early screening before the NHS Nuchal Translucency scan. NIPT can be performed after the NHS 11-14 week Nuchal Translucency Scan, or even in the mid term of pregnancy after the 20 week anomaly scan.
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What is Non-Invasive Prenatal Testing?
It has been discovered that a blood sample taken from the mother from 10 weeks of pregnancy onwards can be analysed for cell free fetal DNA (cfDNA), which represents a sample of the fetal-placental DNA, derived from placental trophoblasts, in the mother’s blood.
This prenatal screening method involves taking a safe blood sample from the mother’s arm. There is no increased miscarriage risk to your baby from having this simple, safe maternal blood test. The cell free fetal DNA (cfDNA) which is present in the mother’s blood is then analysed, the results determine if there is a high probability or low probability of the baby having one of the three screened conditions; Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. These conditions are also known as Trisomy 21, Trisomy 18 and Trisomy 13.
NIPT can be used in twin, singleton donor and surrogate pregnancies. You can also choose to find out the sex of your baby by looking at baby’s chromosomes, this is optionally included in your NIPT. In some circumstances it may not be possible for the NIPT to report on the sex of your baby, such as Vanishing twin pregnancies.
Non-invasive prenatal testing is available from several different laboratories across Europe, China and the U.S.A. The NIPT by TDL is processed and analysed by The Doctors Laboratory ( TDL) in London. The Panorama NIPT is processed and analysed by Natera inc. in the USA. The INVITAE Test NIPT is processed and analysed in the USA.
Why choose Non-Invasive Prenatal Testing?
Parents to be who wish to find out the likelihood that their baby has one of three chromosomal conditions; Down’s syndrome (T21), Edward’s syndrome (T18) or Patau's syndrome (T13) choose NIPT. This prenatal test can be performed two weeks earlier than the NHS 11-14 week Nuchal Translucency screening.
Tiny structures inside your baby’s cells called chromosomes carry the genes that determine how your baby develops. There are 23 pairs of chromosomes per cell, however changes may occur during the production of sperm or egg cells which can lead to your baby having an extra chromosome. Although babies with Trisomy 21, Trisomy 18 and Trisomy 13 are born to mothers of all ages, maternal age increases the likelihood of the presence of these conditions. NIPT analyses the cffDNA in the maternal blood, to determine if there is an increased likelihood that your baby has an extra chromosome present. Downs Syndrome, Edwards Syndrome and Pataus Syndrome are spectrum conditions varying from mild to severe presentation.
The Nuchal Translucency screening offered by the NHS determines a background chance based on maternal age. From the maternal age of 35 years of age onwards this background chance increases substantially. This increases the likelihood of receiving a high probability result from the Nuchal Translucency screening. Due to the limitation of the Nuchal translucency screening, this lowers the positive predictive value (PPV) of the test, meaning that those over 35 are more likely to receive a high probability result, even if the baby does not have the condition.
NIPT has a higher positive predictive value than the Nuchal translucency screening. This means less high probability results where the condition is not actually present. We do not use the term false positives, as these are screening tests therefore, they do not determine positives or negatives. They offer likelihoods, from low to high.
NIPT is particularly recommended for those over 35 years of age, parents to be who have had a high probability result in their current or previous pregnancy, or a confirmed chromosomal condition in a previous pregnancy. It is for those who wish to avoid unnecessary invasive testing, which carries a risk of miscarriage.
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