Amniocentesis is a prenatal diagnostic test in which amniotic fluid is extracted via a long thin needle inserted through the maternal abdomen into the uterus and the amniotic sac. The procedure is usually performed between the fifteenth and eighteenth week of gestation and results can be obtained nine to fourteen days later. Some major medical centers now use a procedure called Fluorescence In Situ Hybridization (FISH) to obtain results within twenty-four hours. It is recommended for women over age thirty-five and those having risk factors for genetic abnormalities. Amniocentesis is a reliable (95% accuracy rate) indicator of chromosomal abnormalities such as Down syndrome, or genetic disorders such as Tay Sachs disease, Hunter's syndrome, or neural tube abnormalities such as spina bifida and others. While usually safe, amniocentesis can trigger cramping, leakage of amniotic fluid, vaginal bleeding, and it may increase the risk of miscarriage by about .5 to 1 percent.
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Yvonne M. Caldera