Amniocentesis is a test that can be done during pregnancy to look for these problems in the developing baby:
- Birth defects
- Genetic problems
- Lung development
Culture - amniotic fluid; Culture - amniotic cells; Alpha-fetoprotein - amniocentesis
How the Test is Performed
Amniocentesis removes a small amount of fluid from the sac around the baby in the womb (uterus). It is most often done in a doctor's office or medical center. You do not need to stay in the hospital.
You will have a pregnancy ultrasound first. This helps your health care provider see where the baby is in your womb.
Numbing medicine is then rubbed onto part of your belly. Sometimes, the medicine is given through a shot in the skin on the belly area.
Your health care provider inserts a long, thin needle through your belly and into your womb. A small amount of fluid (about 4 teaspoons or 20 milliliters) is removed from the sac surrounding the baby.
The fluid is sent to a laboratory. Testing may include:
- Genetic studies
- Measurement of alpha-fetoprotein (AFP) levels (a substance produced in the liver of the developing baby)
- Culture for infection
Results of genetic testing usually take about 2 weeks. Other test results come back in 1 to 3 days.
Sometimes amniocentesis is also used later in pregnancy to:
- Diagnose infection
- Check whether the baby's lungs are developed and ready for delivery
- Remove excess fluid from around the baby if there is too much amniotic fluid (polyhydramnios)