Amniocentesis performed at the 16-18 week of gestation uses amniotic fluid to test for chromosomal abnormalities. It can also be used to find biochemical abnormalities at the genetic level, detecting up to 180 genetic disorders. CVS is performed 10-12 weeks into gestation and uses chorion tissue for chromosomal analysis in biochemical and DNA studies. This test is not widely used because of correlation to producing newborns with limb abnormalities. PUBS can be performed after week 18 and is used only as a confirmation test based on results from previous tests.
Fetal biopsy involves taking fetal tissue for DNA testing.
Fetal cell sorting is an experimental procedure that takes blood from the mother and tests the fetal cells in the mother's blood. All 50 states and the District of Columbia require by law the administration of genetic screening tests on all newborns. Some states screen for maple syrup urine disease, hemocystinuria, biotinidase deficiency and other rare disorders. Nearly all the preceding diseases, if dealt with immediately, can be treated and the individual can lead a normal life. However, if not detected within days of birth the individual will become mentally retarded and may soon die after birth.