An amniocentesis is a test done between 15 to 18 weeks gestation where a doctor, using a thin needle, will obtain a sample of amniotic fluid from your womb. The amniotic fluid contains cells from your baby that can be examined to determine the baby’s genetic makeup.
This test is often done to determine if your baby carries a genetic condition such as Down’s syndrome. The results usually take about 10 to 12 days to come back, and the test is over 99% accurate. Amniocentesis can also be used to determine if your baby has a defect in its neural tube (the part of the body that will make up the spinal cord and the brain).
In the third trimester(27-40 weeks), an amniocentesis can be used to see if an intra-amniotic infection is present and to verify if your baby’s lungs are mature.
Your doctor will use an ultrasound to guide a thin needle through your abdominal wall into your uterus. The ultrasound imaging will help the doctor aim the needle at a pocket of amniotic fluid, avoiding your baby’s body. The discomfort is usually much less than expected.
Unfortunately, there is a chance that an amniocentesis can result in a miscarriage. The rate of having a miscarriage after an amniocentesis varies, but it is usually quoted as being between 1 in 300 to 1 in 500. Do note that in about 1% of cases, women experience some fluid leakage or vaginal spotting after the procedure, and most often clears up after a week after the procedure. In over 90% of cases, this spotting will resolve on its own. Talk to the doctor who will be performing the amniocentesis in order to learn what his or her miscarriage rate is.
Due to the possible risk of a miscarriage, it is important to take it easy for several days after the amniocentesis. There is no research showing exactly how long one should rest after an amniocentesis. However, several large medical centers recommend bed rest for 1 day, no lifting objects over 15 pounds (7kg) for 48 hrs, no strenuous exercise for 72 hours, no air travel for 72 hours, and no intercourse for 7 days.