During pregnancy, the fetus is surrounded by amniotic fluid, a substance similar to water that contains fetal cells which are shed during development. These cells can be used to provide genetic and other important information about the health of the fetus before birth.

What is amniocentesis?

Amniocentesis is a procedure in which a small amount of amniotic fluid from the sac surrounding the fetus is removed and tested. The sample of amniotic fluid (less than 1 ounce) is removed with a fine needle inserted into the uterus through the abdomen, under ultrasound guidance.

The fluid is then sent to a laboratory for analysis. Different tests can be performed on a sample of amniotic fluid, depending on what the underlying concern is.

Why is an amniocentesis performed?

Amniocentesis is often performed to determine if the fetus is affected with a genetic condition, such as Down syndrome (a chromosomal abnormality). Because genetic amniocentesis presents a small risk for both the mother and her baby, it is generally offered only to women who have a significant risk for genetic disorders. These can include women with:

  • Fetal abnormalities noted on an ultrasound
  • A positive screening test for a chromosome abnormality
  • A family history or have previously had a child with a genetic disorder

It may also be offered to mothers who will be 35 or older at the time of delivery.

Amniocentesis can also be used to detect certain diseases, which are caused by abnormalities in a single gene. It may be used if there is risk for that disease in the fetus based on either family history or carrier screening testing in the parent(s). Some diseases include:

  • Sickle cell disease
  • Cystic fibrosis
  • Tay-Sachs disease
  • Muscular dystrophy

When is amniocentesis performed?

If your doctor has recommended an amniocentesis, the procedure can be performed any time after the 15th week of pregnancy. Most are done prior to 20 weeks of pregnancy.

How accurate is amniocentesis?

The accuracy of amniocentesis approaches 100%.

may be an inability to collect enough amniotic fluid to test, or failure of the collected cells to grow when cultured.

Does amniocentesis have risks?

There is a small risk that an amniocentesis could lead to loss of the pregnancy (miscarriage) or premature delivery (less than 1%, or approximately 1 in 400). Injury to the baby or mother, infection, or Rh isoimmunization are other potential complications, but are extremely rare.

Can I choose not to have an amniocentesis?

Yes. You will receive genetic counseling before the procedure. After the risks and benefits of amniocentesis have been thoroughly explained, you can choose whether or not you want to have the procedure.

What happens during an amniocentesis?

  1. A small area of the abdomen is cleansed with an antiseptic.
  2. Under ultrasound guidance, the physician inserts a thin, hollow needle through your abdomen and uterus, and into the amniotic sac, away from the fetus.
  3. A small amount of fluid is removed through the needle and sent for laboratory analysis.

You are likely feel the initial needle stick and minor menstrual-like cramping or discomfort during the procedure. This can last for a few hours after the procedure.

Can I resume normal activity after an amniocentesis?

After an amniocentesis, it is best to go home and relax for the rest of the day. You should not exercise or perform any strenuous activity. Avoid sexual relations. If there have been no complications, you may resume all of your normal activities the day after the procedure.

When should I call my doctor?

After an amniocentesis, call your doctor if you develop:

  • Fever or vaginal bleeding
  • Vaginal discharge or leakage of fluid
  • Abdominal pain greater than just mild cramps

When will I receive the results?

The final results of the amniocentesis are usually available in 2 weeks. Some preliminary information may be available as early as 2 to 3 days. You can expect a phone call from a genetic counselor to review your results as they come back.


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 3/15/2017…#4206