Amniocentesis

Performed when you’re between 15 and 21 weeks pregnant, amniocentesis is a procedure to obtain amniotic fluid. The fluid can be tested for chromosomal disorders and open neural tube defects. It can also be used to test for certain genetic disorders such as cystic fibrosis and sickle cell disease, if your pregnancy is determined to be at increased risk for a genetic disorder. It can’t test for the 3-5% of birth defects that are everyone’s background risk.

The procedure involves withdrawing amniotic fluid (the fluid surrounding the developing baby). This fluid contains fetal cells that can be used for chromosome testing. The fluid also contains alpha-fetoprotein (AFP) that is used in testing for open neural tube defects.