<\/span><\/h2>\nThe term amniocentesis is derived the Latin amnion<\/em>, the membrane that forms the protective sac around a growing embryo, and the Greek kentesis<\/em> meaning to puncture or to prick. This accurately describes the amniocentesis definition<\/strong> of the insertion of a needle through the amnion in order to extract a small amount of amniotic fluid. This fluid can reveal genetic information about the foetus, including the presence or absence of genetic abnormalities.<\/p>\nThe amniocentesis test<\/strong> has been used for the latter purpose since the 1950s and for a long time it remained the major diagnostic test for abnormalities such as Down\u2019s Syndrome. The test has a high accuracy rate of around 99.4%. It is an invasive test and carries a small but highly significant risk; one which can lead to some extremely difficult choices for prospective parents. This is the one-in-a-three hundred chance that the test will cause a miscarriage.<\/p>\n