How It Is Done continued...
You will be asked to expose your belly. You will then lie on your back with it slightly raised to relax your belly muscles. Your lower belly will be cleaned with a special soap.
Your doctor checks the position of your fetus and the placenta with a fetal ultrasound. Ultrasound uses sound waves to make a picture of the uterus, your fetus, and the placenta on a TV screen. Your fetus's heart rate can also be watched during the test using ultrasound. For more information, see the topic Fetal Ultrasound.
With the ultrasound picture as a guide, your doctor gently puts a thin needle through your belly and into your uterus without hurting your fetus or the placenta. If your fetus moves too close to the needle, the needle will be taken out and your doctor will try again in another spot.
About 2 Tbsp (30 mL) of amniotic fluid is taken out in a syringe attached to the needle, and then the needle is taken out. The site is covered with a bandage.
The whole test takes about 15 minutes. The thin needle is only in your belly for 1 to 2 minutes. Your fetus's heart rate and your blood pressure, pulse, and breathing will be checked before, during, and after the test.
How It Feels
You will feel a sharp sting or burn in your belly where the needle is inserted. This lasts for only a few seconds. When the needle is put into your uterus, you again will feel a sharp cramp for a few seconds.
When the amniotic fluid is taken out, you may get a feeling of pulling or pressure in your belly. To keep yourself comfortable, breathe slowly and relax your belly muscles during the test.
Amniocentesis is generally very safe. There is a chance (about 1 out of 400) that this test may cause a miscarriage.1 In some studies, the risk is a little higher, about 2 to 4 out of 400.2 There is also a risk of too much bleeding (hemorrhage), infection of the amniotic fluid (amnionitis), or leakage of amniotic fluid. In very rare cases, a fetus may be poked by the needle during the test. Your doctor does all he or she can to put the needle in a safe spot. Most fetuses float away from the needle tip.