Invasive procedure to obtain amniotic fluid that contains cells sloughed from the fetus. Some biochemical tests can be performed directly on the fluid; most tests first require cell culture. It is generally not performed until 15 weeks of gestation; recent estimates of procedural risk of fetal loss are as low as 0.06%. Cell culture for chromosome analysis takes 5 " “7 days; slightly longer culture times are required to obtain material for biochemical or molecular genetic tests.
Use
Provides fetal material for chromosome (cytogenetic) testing, biochemical testing (metabolic disorders/inborn errors of metabolism), and molecular DNA " “based testing for inherited disease (e.g., CF, fragile X).
Limitations
Not performed until second trimester, which delays decisions regarding pregnancy termination.