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Jennifer L.W. Fink
Registered Nurse

What Is Cordocentesis?

What is percutaneous umbilical blood sampling?

Percutaneous umbilical blood sampling is also known as cordocentesis. It’s a specialized form of testing that can be used to determine if your baby carries certain genetic or blood defects. It’s only used in certain circumstances in which a woman and her doctor agree that the need for information outweighs the risks of the procedure, which include miscarriage, blood loss, infection and premature rupture of membranes. Usually, that’s when chorionic villus sampling (CVS) or amniocentesis test results are inconclusive.

Unlike amniocentesis, which tests a sample of amniotic fluid, the fluid that surrounds your baby in utero to determine information about your baby, cordocentesis uses a sample of baby’s blood, pulled from his umbilical cord. For the procedure, a needle is inserted through the mom-to-be’s abdomen (don’t worry — there’s local anesthesia to help numb you) and into the umbilical cord; real-time ultrasound images are used to guide the placement of the needle. Fetal blood is then drawn from the umbilical cord and sent to a lab for analysis.

The benefit of cordocentesis is that it has high accuracy in detecting the presence of certain chromosomal abnormalities (such as Down syndrome), fetal blood disorders (like fetal hemolytic disease or anemia), Rh incompatibility and fetal infections. But tests can’t detect how mild or severe a condition will be.

As with any other test, talk to your doctor and get all the facts before undergoing any testing. And read more about cordocentesis and other prenatal tests here.

*Plus, more from The Bump:
Why CVS/amnio? 

—Larry Kieft, MD, OB/GYN, Poudre Valley Medical Group, Fort Collins, Colorado

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