Amniocentesis is a common test that is usually performed 15 to 20 weeks from the first day of your last menstrual cycle. The test analyzes cells in your baby’s amniotic fluid (bag of water).

Amniocentesis can diagnose genetic birth defects and is most commonly used to determine if there are chromosomal abnormalities or, in later pregnancy, if the baby’s lungs are mature. Amniocentesis can identify several hundred genetic disorders, including chromosomal disorders such as Down’s Syndrome. Neural tube defects, such as spina bifida and anencephaly, can also be diagnosed.
About The Test:

Amniocentesis is the most accurate test to diagnose chromosomal anomalies. Many women 35 years old and older choose to perform this test. Amniocentesis is performed under ultrasound guidance to first locate the fetus and the placenta. You will feel a small pin prick when your doctor inserts a needle into your abdomen to withdraw approximately 10 to 20 cc’s (or 2 to 4 teaspoons) of fluid. Your body will replace this fluid within hours.

The test is considered safe; however, there are risks. This risk of miscarriage is under ½%. Some women leak amniotic fluid or notice vaginal spotting. A fever over 100 degrees, chills, contractions, irritability and uterine tenderness may indicate an infection. If you have any of these symptoms, call your doctor immediately.

You will usually receive the results of this test within 2 to 3 weeks. This much time is needed in order to grow a sufficient number of fetal cells to analyze. The results are more than 99% accurate in detecting chromosomal problems.