Placental DNA circulates freely in the maternal blood stream which can
be sampled by venipuncture of the expecting mother. NIPS is able to test for extra chromosome 13, 18 or 21 material in foetal placental DNA. The foetal DNA originates from placental trophoblasts. NIPS has been shown to have significantly higher accuracy than other non-invasive screening tests such as nuchal translucency ultrasound (higher sensitivity and higher specificity). Using a screening test with a higher detection rate leads to fewer undetected cases while a higher specificity leads to fewer unnecessary invasive procedures.
Non-Invasive Prenatal Screening