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How It Is Done continued...

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.

Amniocentesis has a very small risk of causing bleeding that could lead to mixing your blood and your fetus's blood. So if you have Rh-negative blood, you will be given the Rh immunoglobulin vaccine (such as RhoGAM) to prevent Rh sensitization, which could harm your fetus if he or she has Rh-positive blood.

After the test

After the test, you may have some mild cramping. You should not do any strenuous activity for several hours after the test. Also, do not douche, use tampons, or have sex after the test. By the next day, you can do your normal activities, unless your doctor tells you not to.

Call your doctor right away if:

  • You have moderate or severe belly pain or cramping.
  • You develop a fever.
  • You become dizzy.
  • Fluid or blood leaks from your vagina or from the needle site.
  • Redness or swelling develops at the needle site.

WebMD Medical Reference from Healthwise

Last Updated: April 04, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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