Amniocentesis Facts
By Ellen Neuborne

Find out what amniocentesis is and why you may need one.

 

What is it?

Amniocentesis is a prenatal test in which a doctor, guided by ultrasound, passes a needle through your abdomen and into the amniotic sac surrounding your fetus. A small amount of amniotic fluid is withdrawn and analyzed to screen for fetal defects and certain genetic abnormalities such as Down syndrome. Results of the testing are generally available in two to three weeks.

Who should get one?

There are a variety of reasons why a doctor may recommend an amnio. They include: mother is over age 35; the couple has already had one child with a chromosomal abnormality; the couple has a close relative with a neural tube defect; a screening test, such as a sonogram or an alpha-fetoprotein (AFP) test, yielded an abnormal result.

What are the benefits?

If the test indicates an abnormality, the information can be used to make vital decisions. Should the pregnancy be continued? Are there treatment options that can be pursued even during pregnancy? How can the family prepare for a baby with special needs? Early testing gives you time to cope with these big issues and make the decision that is best for you and your family.

What are the risks?

Although complications are rare, a small percentage of tests result in the leaking of amniotic fluid. There is also a small risk of infection or other complications that can lead to miscarriage. The chance of this happening is between 1 and 200, and 1 in 300. The risk of loss is greater in twin or other multiple pregnancies, since each sac must be entered.

What are the issues?

Is the risk worth the benefit? In other words, is the chance of losing the pregnancy (which may be a very much wanted, normal pregnancy) worth the information obtained from the procedure? This needs careful thought by the future mom and her partner. What will they do with the information if the baby has chromosomal or other abnormalities? Will they consider termination? Be better prepared for a child with special needs? Plan to deliver their baby in a hospital that can care for a newborn with special needs?

Amniocentesis should be done at approximately 16 to 17 weeks' gestation, when sufficient fluid can be easily obtained. The results of the test take two to three weeks, leaving just a short time to consider your options. The legal option of pregnancy termination ends at 24 weeks, and in many institutions sooner.

Deciding whether to have testing of this sort is very difficult for most women. Weigh the risks and benefits, and consider what you would do with the information if you had it.