Noninvasive prenatal testing.

BACKGROUND: Noninvasive prenatal testing (NIPT) has marked a revolution in aneuploidy screening because it allows a simple maternal blood test to detect Down syndrome in a fetus with a very high level of accuracy (at least 99.5% with a false-positive rate of 0.2%).

OBJECTIVE: To describe the new tests that have become available and their place in antenatal screening to help GPs and their patients make informed decisions about their use.

DISCUSSION: Results are available from 12 weeks gestation, giving a high level of reassurance for Down syndrome early in pregnancy. There are concerns, however, that the test is being offered without proper counselling and that women may not have a 12-week ultrasound to exclude significant structural abnormalities, therefore decreasing the early detection of severe abnormalities. In addition, the test is expensive and therefore prohibitive for many women and their families.