Overview
Amniocentesis is done to remove amniotic fluid and cells from the uterus for testing or treatment. Amniotic fluid surrounds and protects a baby during pregnancy.
Amniocentesis can provide useful information about a baby’s health. But it’s important to know the risks of amniocentesis — and be prepared for the results.
Why it’s done
Amniocentesis can be done for a number of reasons:
- Genetic testing. Genetic amniocentesis involves taking a sample of amniotic fluid and testing the DNA from the cells for diagnosis of certain conditions, such as Down syndrome. This might follow another screening test that showed a high risk of the condition.
- Diagnosis of fetal infection. Occasionally, amniocentesis is used to look for infection or other illness in the baby.
- Treatment. Amniocentesis might be done to drain amniotic fluid from the uterus if too much has built up — a condition called polyhydramnios.
- Fetal lung testing. If delivery is planned sooner than 39 weeks, amniotic fluid might be tested to help find out whether a baby’s lungs are mature enough for birth. This is rarely done.
Genetic amniocentesis
Genetic amniocentesis can provide information about the baby’s genes. Generally, genetic amniocentesis is offered when the test results might affect how to manage the pregnancy.
Genetic amniocentesis is usually done between weeks 14 and 20 of pregnancy. Amniocentesis done before week 14 of pregnancy might lead to more complications.
Reasons to consider genetic amniocentesis include:
- Having positive results from a prenatal screening test. If the results of a screening test — such as the first-trimester screen or prenatal cell-free DNA screening — show high risk or are worrisome, amniocentesis might confirm or rule out a diagnosis.
- Having an earlier pregnancy affected by a genetic condition. A health care provider might suggest amniocentesis to look for that condition.
- Being 35 or older. Babies born to people 35 and older have a higher risk of chromosomal conditions, such as Down syndrome. A health care provider might suggest amniocentesis to rule out these conditions if prenatal cell-free DNA screening is positive.
- Having a family history of a genetic condition, or if the parents are carriers of a genetic condition. Besides identifying Down syndrome, amniocentesis can be used to diagnose other genetic conditions, such as cystic fibrosis.
- Having unusual ultrasound findings. A health care provider might recommend amniocentesis to diagnose or rule out genetic conditions associated with unusual ultrasound findings.
