What Is Involved in an Amniocentesis Procedure?

An amniocentesis procedure is performed on a pregnant woman to test for chromosomal abnormalities and/or infections. During the procedure, a large needle is inserted through a woman's abdomen and into the amniotic sac which surrounds a fetus. The needle extracts a small amount of amniotic fluid which is then analyzed.

There are many risks to a woman and her fetus during the time of pregnancy. To prepare for and anticipate those risks may require an amniocentesis procedure to analyze amniotic fluid, the fluid in which a fetus develops. This fluid has proven to reveal many types of birth abnormalities and infections, some of which can be treated or corrected.

Before the amniocentesis procedure begins, a local anesthetic is given to a pregnant woman in order to alleviate the pain which may be caused during the procedure. After the anesthetic takes effect, a doctor will insert a needle through a woman's abdomen, puncturing the wall of the uterus. The doctor uses ultrasound to guide the needle away from the fetus to prevent any injury. The needle will then extract approximately 20 mL of amniotic fluid from the amniotic sac, which the body will then replenish over the next 24-48 hours.

Once a doctor has the amniotic fluid, he or she will then isolate the fetal cells and grow them in a culture medium. They are then stained and analyzed for any chromosomal abnormalities, such as Down syndrome, or infection. The body repairs the amniotic sac puncture through normal healing processes.

The amniocentesis procedure takes place typically somewhere between the 15th and 20th week of pregnancy. In some cases, the test may be performed between 11 and 13 weeks, and this is called an early amniocentesis procedure. Risks include harm to the fetus and possible miscarriage, although these risks are low compared to the risk of not having one. Recent estimates have placed the risk of miscarriage as low as one in 1,600.

Because the amniotic fluid is rich in stem cells, it may in the future take the place of using stem cells by taken from discarded embryos or fetuses. This would sidestep ethical concerns by pro-life advocates who insist that the use of stem cells from embryos or fetuses is immoral. Stem cells are the building blocks of the body and are thus very valuable in research and scientific development. Amniotic stem cells have already been proven capable of engineering cells, such as those found in bone, muscle or fat.