is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, and also used for sex determination in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amniotic sac surrounding a developing fetus, and the fetal DNA is examined for genetic abnormalities.
The sample of amniotic fluid is removed through a fine needle inserted into the uterus through the abdomen, under ultrasound guidance. The test is usually done between 14 and 20 weeks.
Because amniocentesis presents a small risk for both the mother and her baby, the prenatal test is generally offered to women who have a significant risk for genetic diseases, including those who:
- Will be 35 or older when they give birth
- Had a screening test result that shows there may be a birth defect or other problem
- Have previously had a child or pregnancy with a birth defect
- Have a family history of genetic disorders
Amniocentesis does not detect all birth defects, but it can be used to detect the following conditions:
- Chromosomal disorders, including: Down syndrome, trisomy 13, trisomy 18, and sex chromosome abnormalities such as Turner syndrome and Klinefelter syndrome.
- Several genetic disorders, such as cystic fibrosis, sickle cell disease, and Tay-Sachs disease.
- Neural tube defects such as spina bifida and anencephaly.