What is Amniocentesis?

What is amniocentesis?
Amniocentesis is a test performed during the 12th and 20th weeks of pregnancy to check the unborn baby for certain birth defects. The test is not routinely performed, although it is suggested for pregnant women who are 35 or older. An amniocentesis may be suggested by your doctor after you have had an ultrasound or other prenatal tests which indicate a fetal abnormality. Specifically, amniocentesis can diagnose disorders such as chromosomal abnormalities (Downs syndrome), neural tube defects (spina bifida), and a host of other genetic disorders such as cystic fibrosis and anencephaly.

What is the procedure?
During amniocentesis, a long, hollow needle is inserted into the woman's abdomen and through the uterine wall so that a sample of amniotic fluid can be collected. The fluid is then tested for indications of birth defects. Ultrasound is used during the procedure to ensure the needle is inserted as far from the baby and placenta as possible, as well as to ensure that a pocket of amniotic fluid is available from which to draw the sample. Some women report feeling sharp pain when the needle is inserted into the uterus and others report feeling low abdominal pressure when the fluid is extracted.

Why do women choose to have it done?
Most women elect to have the procedure done because they want to put their mind at ease. Some parents choose the test so they can have time to adapt and prepare for a baby with birth defects, or seek out information and support groups. Also, some treatments are available for fetuses in utero, therefore testing can provide opportunities for treatment. Still, others desire amniocentesis so that they may choose to end the pregnancy if it is determined that the baby has a genetic or chromosomal disorder. Note: Amniocentesis is not 100% accurate. Therefore, women who elect to abort a baby as a result of an amniocentesis may be aborting a perfectly healthy baby.

What are the risks?
Amniocentesis is considered a safe procedure and is performed approximately 200,000 times per year, according to the Mayo Clinic. However, as with any invasive procedure, there are potential risks.

Miscarriage is the most notable side effect resulting from amniocentesis. Rates vary between 1 in 200 to 1 in 400. Miscarriage is usually due to an infection being introduced into the womb by the needle, or a leak of amniotic fluid from the uterus caused by the needle puncture.

Side effects for the mother may include cramping, leaking amniotic fluid, or minor irritation around the puncture site.

Since the needle is placed in close proximity of the baby, there is a risk of the baby being punctured. However, precautions such as fetal monitoring and ultrasound guard against this threat.

As with any important medical decision, it is important for women to research the benefits and risks before making a decision. It is also needful that an expectant mother evaluate her own feelings. Will the outcome of the test determine whether or not she carries the baby to term? Are there things she would like to do to prepare for a baby with birth defects? If the outcome of the test does not change her actions, is it worth the potential risks? All of these issues must be considered by women presented with the option of amniocentesis.