Noninvasive prenatal screening (NIPS). This testing analyzes small fragments of DNA that are circulating in a pregnant woman’s bloodafter 10 weeks of pregnancy to determine the risk of certain genetic abnormalities in the unborn.
NIPT is recommended for all types of pregnancies as first line of screening for all pregnancies. More so when The woman is above 30 years of age.
How does the NIPT test work?
It’s a blood test, 5ml blood is collected and sent to the lab for analysis after 10 weeks of gestation. The test counts fragments of DNA from your placenta that’s circulating in your blood, it contains cells from both mother and the fetus. These fragments are free-floating rather than within cells, so they’re called cell-free DNA.
By examining the chromosomes /cell free DNA it can be estimated if the baby carries any high risk of certain disorder. There are normally 23 pairs of a chromosome. If one of the pairs has an extra chromosome, it’s called a trisomy. Down syndrome is also called trisomy 21 because there’s an extra copy of chromosome 21. The NIPT is highly sensitive and picks up more than 99% of cases of Down syndrome. But it is still a screening test rather than a diagnostic test. This means it can only tell you whether there is an increased risk of having a baby with an abnormality, rather than give you a definitive answer.
combined first trimester screening to screen for Down syndrome. This combines results from a blood test, the mother’s age and an ultrasound scan (which measures the thickness of fluid behind the baby’s neck, called the nuchal translucency) to show whether the baby is at increased risk of Down syndrome. The advantage of this type of screening is that the ultrasound can pick up other problems with the pregnancy and estimate the age of the fetus.
What does it test for?
The NIPT is a safe and highly effective way of screening for conditions that include:
- Down syndrome (also called trisomy 21)
- Edwards syndrome (trisomy 18)
- Patau syndrome (trisomy 13)
- Turner syndrome
What does NIPT not screen for?
- Conditions not screened for include:
- Neural tube defects
- Heart defects
- Abdominal wall defects
- Many other chromosomal and genetic disorders
NIPT only screens for some chromosomal conditions. CVS and amnio, on the other hand, can diagnose almost all chromosomal abnormalities.
Why have an NIPT?
The NIPT is highly sensitive and picks up more than 99% of cases of Down syndrome. But it is still a screening test rather than a diagnostic test. This means it can only tell you whether there is an increased risk of having a baby with an abnormality, rather than give you a definitive answer.
Combined first trimester screening to screen for Down syndrome,Includes Nuchal Thickness scan on Ultrasound and results from a blood test, the mother’s age and) to show whether the baby is at increased risk of Down syndrome.
You might be recommended to have an NIPT test if:
- your combined first trimester screening test shows you are at increased risk of having a baby with Down syndrome
- you did not have the combined first trimester screening test because it was too late or the test wasn’t available in your area
- you want to be sure you are at increased risk before you opt for diagnostic tests such as amniocentesis or CVS, which carry a small risk of miscarriage
- you are at increased risk (for example, if you are older or you have had a baby previously with Down syndrome or another chromosomal condition)
- If the result is ‘negative’, ‘normal’ or ‘low risk’, your baby is unlikely to have any of the chromosomal disorders tested. If the result is ‘positive’, ‘abnormal’ or ‘high risk’, this means your baby is likely to be affected.
- If you have an abnormal NIPT result, a diagnostic test such as CVS or amniocentesis can confirm the result. You should discuss your options with your doctor, midwife or genetic counsellor.
- Benefits of NIPT
- NIPT is a simple procedure that provides a lot of useful information. :
- It’s not invasive.
- A simple blood draw taken at a regular prenatal checkup.
- It’s perfectly safe for you and your baby and carries no risk of abortion
- It’s a diagnostic test only but negative results provide a high degree of accuracy
- It’s available very early in pregnancy, at 9 to 10 weeks or later.
- Results are provided fairly quickly .