Diagnostic Cordocentesis | Tampa General Hospital

Diagnostic Cordocentesis 

Cordocentesis is a prenatal test performed to check if a baby has anemia or other disorders.  Cordocentesis, also known as percutaneous umbilical blood sampling, is a type of prenatal test during which some of a baby’s blood is removed from the umbilical cord. The test is usually performed after week 18 of pregnancy.  

When is a Cordocentesis Test Performed? 

Before a baby is born, diagnostic cordocentesis is performed to detect: 

  • Anemia 
  • Genetic disorders 
  • Blood disorders 
  • Infections 
  • Fetal kidney function in babies with lower urinary tract obstruction (LUTO) 

Cordocentesis does pose certain risks for the baby, so there are other prenatal tests—such as aminocentesis and chorionic villus sampling—that are often the first tests performed to detect certain conditions. When those tests are unable to provide meaningful results, cordocentesis may be performed. It is most often used to determine whether the baby is anemic.   

Procedure Details  

Before a diagnostic cordocentesis test, a sample of the mother’s blood is taken and she may be administered antibiotics intravenously to help prevent uterine infection.  

The procedure typically follows this process: 

  • The mother will lie on her back on an examination table and an ultrasound specialist will apply gel to her belly.  
  • An ultrasound wand called a transducer will be moved across the belly and an image of the baby and his or her position in the womb will show up on a monitor.  
  • Using ultrasound guidance, a thin needle will be inserted through the mother’s abdomen and into her uterus. A slight sting may be felt when the needle enters the skin and cramping is possible when the needle enters the uterus. 
  • A small sample of blood will be removed from the umbilical cord and sent out for testing.  
  • The needle will be removed.  

What to Expect 

A women undergoing cordocentesis may be asked to avoid eating or drinking after a certain time the night before the procedure. It is typically performed in a hospital if the mother is more than 23 weeks pregnant in the event an emergency delivery is necessary.  

Diagnostic cordocentesis can pose risks that include: 

  • Fetal bleeding 
  • Infection 
  • Cord hematoma 
  • A slowed heart rate for the baby  
  • Pregnancy loss 


All types of prenatal tests, including cordocentesis, are helpful in that they allow doctors to identify and diagnose problems before birth so prenatal treatments can begin. If nothing else, discussions about treatments and methods of caring for a child with a particular disorder or condition can be planned out in advance and implemented after birth.  

At Tampa General Hospital, we take a multidisciplinary approach to maternal-fetal treatments, ensuring that both mother and baby receive world-class care. We are especially skilled and equipped to offer high-risk pregnancy care for even the most complex cases.