NIPT Non Invasive Prenatal Test as screening for T21
What is Non Invasive Prenatal Test NIPT ?
NIPT is an exciting new development in prenatal diagnosis. NIPT uses free fetal DNA that is found in the pregnant mother’s blood to diagnose genetic conditions like T21.
Cell free DNA normally exists in the pregnant mother’s blood. About 1-3% of cell free DNA comes from the baby during pregnancy. More specifically it originates from the baby’s placenta.
New technological achievements have allowed to quantify millions of tiny fetal DNA fragments to accurately predict the risk of a baby having Trisomy 21 18 or 13.
A number of large scale studies have shown that the Non Invasive Prenatal Test NIPT is highly accurate indemnifying more than 99% of babies with T21 with a very small chance of a falsely positive result (less than 0.5%)
The test is still considered to be a screening test and the reporting Labs will recommend a positive result to be confirmed by and invasive procedure amniocentesis or chorionic villus sampling CVS depending on the gestational age.
What are the advantages of Non Invasive Prenatal Test NIPT?
- Non Invasive Prenatal Test NIPT is not invasive as it involves a simple blood test
- There is no risk for miscarriage because of Non Invasive Prenatal Test NIPT
- Non Invasive Prenatal Test NIPT is highly accurate
What are the disadvantages of Non Invasive Prenatal Test NIPT?
- With Non Invasive Prenatal Test NIPT it takes up to 14 days to get results.
- In up to 5% of cases there is not enough free DNA and the Non Invasive Prenatal Test NIPT can not give a result and has to be repeated.
- Non Invasive Prenatal Test NIPT is and expensive test.
As with all the tests offered during pregnancy you need to discuss with your doctor about Non Invasive Prenatal Test NIPT. This ensures you understand the value and the limitations of the test so you can make an informed decision.
Who can have this Non Invasive Prenatal Test NIPT?
You need to be over 10 weeks pregnant to have the test done. The gestation should be confirmed by ultrasound.
Non Invasive Prenatal Test NIPT has not yet been fully validated for mothers who carry multiple pregnancies so discuss with your Obstetrician whether this is an option for you.
The following are the groups of mothers that the American College of Obstetrician & Gynecologists recommends Non Invasive Prenatal Test NIPT to be best considered ;
- Maternal age 35 years or older at delivery
- Fetal ultrasonographic findings indicating an increased risk of aneuploidy
- History of a prior pregnancy with a trisomy
- Positive test result for aneuploidy, including first trimester, sequential, or integrated screen, or a quadruple screen.
- Parental balanced robertsonian translocation with increased risk of fetal trisomy 13 or trisomy 21.
Do I still need an ultrasound?
Non Invasive Prenatal Test NIPT does not replace the need for a first trimester or second trimester ultrasound. First trimester scanning is an essential part of pregnancy care that offers detailed early anatomical information for your baby. NIPT will not detect anatomical / structural problems of the baby like heart problems brain or spine anomalies.
Does Non Invasive Prenatal Test NIPT replaces invasive tests like amniocentesis or CVS ?
The best thing about Non Invasive Prenatal Test NIPT is that it reduces the cases that an amniocentesis or a CVS is needed. Less than 1% of mother will need further invasive testing compared to 7-10% with the current screening tests. However it does not replace them as diagnostic tests. Still the recommendation is that a positive result from NIPT needs to be confirmed by CVS or amniocentesis. NIPT gives information only for T21, T18 and T13. The genetic results from CVS or amniocentesis give a lot more information about the genetic make up of the baby.
Dr George Michailidis
Fetal & Maternal Medicine Consultant
Obstetrician & Gynaecologist
Genesis Perinatal Care Clinic Dubai