The New Dictionary of Cultural Literacy, Third Edition. 2002.
amniocentesis
(am-nee-oh-sen-TEE-sis) A procedure for finding certain disorders in a fetus during pregnancy. In amniocentesis, a small amount of the salty liquid that surrounds the fetus in the amniotic sac is drawn out through a needle inserted into the mothers abdomen. The fluid generally contains some isolated cells from the fetus. These cells are analyzed to detect abnormalities in the chromosomes of the fetus, such as Downs syndrome, and may also be used to judge some other conditions, such as the maturity of the fetuss lungs.