Why it's done

Cordocentesis is used primarily to detect and treat blood conditions, such as fetal anemia — a low amount of healthy red blood cells in a developing baby.

Cordocentesis is usually done when a diagnosis can't be made from amniocentesis, chorionic villus sampling, ultrasound or other methods. Cordocentesis carries a higher risk of complications to the baby, including death, than other procedures do. Your health care provider will offer the procedure only if other options aren't available or they won't produce results quickly enough.

Rarely, cordocentesis might be used to check fetal chromosomes through chromosome microarray or karyotype analysis. Blood obtained through cordocentesis can also potentially be used for other types of genetic studies.