Amniocentesis is an invasive, diagnostic antenatal test. It involves taking a sample of amniotic fluid in order to examine fetal cells found in this fluid.
Amniocentesis is usually reserved for those women considered at higher risk of carrying a fetus with a chromosomal or genetic abnormality. The amniotic fluid extracted contains cells from the amnion and fetal skin, lungs and urinary tract, which can then undergo chromosomal, genetic, biochemical and molecular biological analysis.
Annually about 5% of the pregnant population are offered an invasive, prenatal diagnostic test, usually either amniocentesis or chorionic villus sampling (CVS).
Amniocentesis is an invasive test posing risk to fetus and mother. It is therefore not used as a screening test.