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Health & Pregnancy

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Risks continued...

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.


Amniocentesis is a test to look at the fluid (amniotic fluid) that surrounds your baby (fetus).

Normal amniotic fluid is clear to light yellow in color and does not contain any harmful bacteria. The cells can be tested for problems.

  • Cells from your fetus are looked at carefully for the proper number and arrangement of the cell parts (chromosomes) that show genetic disease. Normally there are 46 chromosomes in each cell, arranged in 23 pairs. Chromosomes also tell the gender of your fetus.
  • The amounts of some substances in the amniotic fluid may be measured. These results can find some birth defects, genetic diseases, and the maturity of your fetus.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • If there is blood from your fetus in the amniotic fluid. This can falsely increase the level of the substances alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) levels, which test for neural tube defects.
  • If the amniotic fluid is exposed to light. This can falsely lower bilirubin levels.
  • If there is blood or meconium in the fluid. This may cause an incorrect result for the test that checks to see whether your baby's (fetus's) lungs are mature.

WebMD Medical Reference from Healthwise

Last Updated: June 04, 2014
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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