Noninvasive Prenatal Testing (NIPS)
NIPS analyses cell-free DNA (cDNA) from the fetus that circulates in the mother's blood Detects fetal chromosomal aneuploidies from the mother's blood
of DNA comes from apoptotic cells derived from:
Who should get an NIPS?
Advanced maternal age, High risk by biochemical screening
Pregnant women who wish to have screening for Trisomy 13, 18 & 21
Previous history of pregnancy loss
Patients that are not eligible for invasive testing
- Placental previa, symptoms of miscarriage, HBV or HIV patients
Recommendation for the use of NIPS
Non-invasive prenatal testing for trisomies 13, 18 & 21 should be an option available to women at increased risk in lieu of amniocentesis.
Pretest counselling of these women should include a discussion of the limitations of non-invasive prenatal testing.
No irrevocable obstetrical decision should be made in pregnancies with a positive non-invasive prenatal testing result without confirmatory invasive diagnostic testing.
Why should you perform an NIPS?
Early Screening: - Can be carried at early gestational age of 11 weeks and allows sufficient time for further confirmatory investigation.
Low Risk: - Only 10 ml blood is required.
Highly Effective: - Can detect Aneuploidy even at Fetal Fraction (cDNA) as low as 4%.
High Accuracy: - Massive Parallel Sequencing of cDNA to generate 20 million reads per sample.
NIPS may not be suitable for:
Gestational age less than 10 weeks - due to low fetal fraction of cell free DNA in maternal blood Not recommended for women with multiple gestations - since it is not possible to determine which of the two fetuses is affected. If the parents are carriers of chromosomal abnormalities - interference in data interpretation – false positive Chromosomal structural changes, translocations or mutations in single genes cannot be detected by NIPS.