During amniocentesis, fluid is removed by placing a long needle through the abdominal wall into this sac. Sometimes, the woman's skin is injected first with a local anesthetic, but this is not always necessary. Occasionally, the amniocentesis needle is guided into the sac with the help of ultrasound imaging. Once the needle is in the sac, a syringe is used to withdraw the clear amber-colored amniotic fluid, resembling urine. The volume of fluid withdrawn depends upon the age of the fetus and the reason for the testing.
Chromosomes are microscopic messengers that contain all of the genetic information in our cells.
The amniotic fluid contains numerous free-floating fetal cells that can be grown in a laboratory. When these cells multiply and reach a certain number, their chromosomes or genes are extracted and analyzed. It takes about two weeks to perform chromosome analysis. The fluid also contains proteins, minerals and other compounds that can be tested, and may take 1 to 7 days to perform. Data obtained from amniotic fluid can help women make informed decisions regarding their pregnancies and babies.