Amniocentesis
Amniocentesis
Amniocentesis is a prenatal testing procedure usually performed during the second or third trimester of pregnancy. It can diagnose certain chromosomal conditions (such as Down syndrome) or genetic conditions (such as cystic fibrosis). During amniocentesis, your healthcare provider uses a thin needle to remove a small amount of amniotic fluid from the sac surrounding the fetus. This fluid sample then gets tested in a laboratory.
During pregnancy, the fetus grows inside the amniotic sac. Amniotic fluid surrounds and protects the fetus inside the amniotic sac. It also contains some of the fetus’s cells. These cells contain genetic information that helps diagnose genetic conditions.
Who gets amniocentesis?
Your healthcare provider may recommend amniocentesis during pregnancy when:
- Ultrasound testing detects a fetal abnormality.
- A prenatal screening test detects an increased risk for a chromosome disorder.
- Certain genetic disorders (such as sickle cell disease or cystic fibrosis) run in your family or you test positive as a carrier of a genetic disorder.
- You’re older than 35 at the time of delivery. This is because individuals over 35 have a higher chance of having a baby with a chromosomal disorder.
What does amniocentesis test for?
An amniocentesis test can detect chromosomal, genetic disorders or congenital disabilities (sometimes called birth defects) such as:
- Down syndrome.
- Tay-Sachs disease.
- Neural tube defects such as spina bifida or anencephaly.
This test can also evaluate:
- Fetal lung development: This is helpful if you need to give birth sooner than expected to protect the health of you or the fetus.
- Rh disease: This is a potentially serious condition where you and the fetus have different blood Rh types.
Amniocentesis is sometimes used to treat polyhydramnios (when you have too much amniotic fluid). Providers use amniocentesis to remove excess fluid.
When is amniocentesis performed?
Most amniocentesis procedures happen between 15 and 20 weeks of gestation (during the second trimester of pregnancy). Having an amniocentesis earlier in pregnancy poses more risks, such as miscarriage.
In some cases, healthcare providers perform amniocentesis tests later in pregnancy. If your provider recommends this test to check fetal lung development or treat polyhydramnios, it will likely happen during the third trimester.