Overview & Description
Amniocentesis is a procedure in which a small sample of the amniotic fluid is taken from the amniotic sac. The amniotic sac is the fluid-filled bag that surrounds the fetus in the uterus of a pregnant woman. It has the same genetic makeup as the fetus.
Who is a candidate for the procedure?
A woman may wish to have an amniocentesis done if:
An amniocentesis may also be offered to a woman who has an abnormal alpha fetoprotein blood test result. A high level of AFP may indicate a neural tube defect, such as spina bifida. A low level can indicate the presence of Down syndrome.
Amniocentesis can detect many disorders in a fetus, including:
Amniocentesis is usually performed 15 to 18 weeks after the woman has missed a period. A chorionic villus sampling is a similar procedure that involves taking a sample of the fluid in the sac surrounding the fetus. It is done several weeks earlier in the pregnancy.
Amniocentesis is occasionally done in the third trimester, toward the end of the pregnancy. It may be done at this time for the following reasons:
How is the procedure performed?
Shortly before the procedure, the woman will be asked to fill her bladder. The full bladder helps the healthcare provider see the pelvic organs with a pregnancy ultrasound. A local anesthetic is used to numb a small area on the woman’s abdomen. The provider uses the ultrasound to guide the insertion of a thin needle. A small amount of amniotic fluid is withdrawn and sent to the lab for testing.
Preparation & Expectations
What happens right after the procedure?
The woman is allowed to go home shortly after the procedure.
Home Care and Complications
What happens later at home?
After an amniocentesis, the woman should avoid strenuous exercise for 1 to 2 days. One to 2% of women have cramping, spotting, or amniotic fluid leak after the procedure. These effects usually stop within a few days. Test results will be available in 1 to 2 weeks.
What are the potential complications after the procedure?
The biggest risk of amniocentesis is miscarriage. The risk for miscarriage is between 1 in 400 and 1 in 200 amniocenteses. About 1 in 1,000 amniocenteses causes a uterine infection. Any new or worsening symptoms should be reported to the healthcare provider.
Article type: xmedgeneral