How to say it: AM-knee-o-sen-TEE-sis
by Cynthia M. Johnson, MA
Amniocentesis is a test during pregnancy. It removes a small amount of the fluid that surrounds the baby for testing.
Reasons for Procedure
This procedure is done on those at high risk after 15 weeks of pregnancy. It tests cells in the fluid to look for signs of:
This test may also be done to make sure the baby's lungs are growing as expected.
Problems are rare, but all procedures have some risk. The doctor will go over some problems that could happen, such as:
Things that may raise the risk of problems are:
What to Expect
Prior to Procedure
The healthcare team may meet with you to talk about:
The doctor will give you a local anesthesia. The area will be numbed.
Description of the Procedure
An ultrasound will be used during the procedure. This will let the doctor see where the needle is. The belly will be cleaned. A very thin needle will be inserted through the skin and into the uterus. A few teaspoons of amniotic fluid will be removed. The needle will be removed. The doctor will make sure that the baby's heartbeat is normal.
How Long Will It Take?
About 45 minutes
Will It Hurt?
Cramps and light bleeding are common in the first few hours after the test.
At the Care Center
Right after the procedure, the staff may:
Rest will be needed in the first 24 hours before going back to activities. The health team will call with the test results.
Call Your Doctor
Call the doctor if you are not getting better or you have:
If you think you have an emergency, call for medical help right away.
American Congress of Obstetricians and Gynecologists
American Pregnancy Association
Canadian Women's Health Network
The Society of Obstetricians and Gynaecologists of Canada
Chorionic villus sampling: CVS. American College of Obstetricians and Gynecologists website. Available at:
...(Click grey area to select URL)
Accessed July 21, 2020.
Delaney M, Matthews DC. Hemolytic disease of the fetus and newborn: managing the mother, fetus, and newborn. Hematology Am Soc Hematol Educ Program. 2015;2015:146-151.
Hemolytic disease of the fetus and newborn (HDFN). EBSCO DynaMed website. Available at: https://www.dyname.... Updated December 20, 2019. Accessed July 21, 2020.
Routine prenatal care. EBSCO DynaMed website. Available at: https://www.dynamed.com/management/routine-prenatal-care-36. Updated January 21, 2020. Accessed July 21, 2020.
Last reviewed January 2021 by EBSCO Medical Review Board Elliot M. Levine, MD, FACOG
Last Updated: 3/12/2021
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