The amniocentesis test is a test in which a needle is used to remove a sample of fluid from the amniotic sac surrounding your baby. The amniotic fluid, which contains cell shed by your baby, is then studied in a lab for analysis. If done for chromosome analysis, amniocentesis is usually performed after the 16th week of pregnancy. If a woman needs to give birth early for some medical reason, amniocentesis might be done shortly before delivery to asses fetal lung maturity.
In the first half of your pregnancy, your doctor may offer amniocentesis if your baby is suspected to be at increased risk for chromosome abnormalities, inherited disorders or neural tube defects. A chromosome analysis will also establish the gender of your baby (but amniocentesis is not offered for gender determination along.)
Amniocentesis is considered to be a relatively safe procedure. The risk of miscarriage caused by amniocentesis ranges from one in 200 to one in 400. In the rare instances tat amniocentesis causes a miscarriage, it is usually because an infection develops in your uterus, the water breaks or labor is induced prematurely. It is not uncommon for women to experience mild complications such as cramping or water leakage or discomfort around the needle site.
The procedure takes about 45 minutes. Your abdomen is cleansed with antiseptic. Some doctors offer a local anesthetic, which can be injected near the site to numb your abdomen. A long, hollow needle is placed through your abdominal wall and into your uterus. A small sample of fluid is withdrawn. Usually the results are back within a few days, although some require up to a week to obtain.