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Amniocentesis, along with chorionic villus sampling, are examples of prenatal diagnostic tests. Amniocentesis or chorionic villus sampling is necessary to conclusively diagnose the majority of genetic disorders, with amniocentesis being the gold-standard procedure after 15 weeks' gestation. [3]
Amniocentesis has become the standard of care for prenatal care visits for women who are "at risk" or over a certain age. The wide use of amniocentesis has been defined as consumeristic. [ 86 ] and some argue that this can be in conflict with the right to privacy, [ 87 ] Most obstetricians (depending on the country) offer patients the AFP ...
Testing Women, Testing the Fetus by Rayna Rapp is a book, published in 1999, about analysis of the social repercussions of prenatal genetic testing.Rapp combines the data she collected herself with historical context of amniocentesis and genetic counseling to argue that amniocentesis and those abortions following positive test results is a social decision as much as an individual one.
Usual follow-up steps include (1) a prenatal ultrasound exam to look for fetal abnormalities and/or (2) measurement of AFP in amniotic fluid obtained via amniocentesis. Maternal serum AFP (MSAFP) varies by orders of magnitude during the course of a normal pregnancy. MSAFP increases rapidly until about 32 weeks gestation, then decreases gradually.
Amniotic fluid is removed from the mother by an amniocentesis procedure, where a long needle is inserted through the abdomen into the amniotic sac, using ultrasound guidance such that the fetus is not harmed. Amniocentesis is a low risk procedure, with risk of pregnancy loss between 1 in 1,500 – 1 in 700 procedures.
Prenatal testing for TSD is usually undertaken when both parents cannot be ruled out as possible carriers. Prenatal testing can be performed by assay of HEX A enzyme activity in fetal cells obtained by chorionic villus sampling or amniocentesis. If an actual mutation has been identified in both parents, then more precise mutational analysis ...
PUBS provides a means of rapid chromosome analysis and is useful when information cannot be obtained through amniocentesis, chorionic villus sampling, or ultrasound (or if the results of these tests were inconclusive); this test carries a significant risk of complication and is typically reserved for pregnancies determined to be at high risk ...
The lecithin–sphingomyelin ratio is a marker of fetal lung maturity. The outward flow of pulmonary secretions from the fetal lungs into the amniotic fluid maintains the level of lecithin and sphingomyelin equally until 32–33 weeks gestation, when the lecithin concentration begins to increase significantly while sphingomyelin remains nearly the same.