Amniocentesis (also referred to as an amniotic fluid test or, informally, an “amnio”) is a medical procedure used primarily in prenatal diagnosis of chromosomal abnormalities and fetal infections as well as for sex determination. In this procedure, a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amniotic sac surrounding a developing fetus. The fetal DNA is then examined for genetic abnormalities.