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Cord Blood Tests

Cord Blood Tests

Alternate Names

  • cord blood test
  • cord blood sampling


Cord blood tests are done on a blood sample collected from the umbilical cord of a newborn. A variety of tests may be done on this blood sample. The type of test done depends on whether there were any problems during the pregnancy or during labor and birth.

Who is a candidate for the test?

A cord blood test is only done on newborns. Most hospitals routinely collect a cord blood sample when a baby is born.

How is the test performed?

Once the baby is born, the umbilical cord is clamped and cut. A second clamp is placed about 8 to 10 inches away from the first clamp. The cord is cut there as well. The blood sample is taken from this section of the cord. No pain is felt by the mother or baby.
For newborns needing intensive care, a catheter may be inserted into either a vein or artery in the umbilical stump and cord blood samples may be taken painlessly and as needed.

What is involved in preparation for the test?

There is no special preparation for a cord blood test.

What do the test results mean?

The following tests may be performed on the cord blood:
  • Blood gases, to evaluate the oxygen and carbon dioxide levels in the newborn baby
  • Cord pH (acid level)
  • Respiratory status, including pH, pCO2, pO2. pH tells how the lungs are functioning in using oxygen and releasing carbon dioxide. pO2 and pCO2 measure the pressure levels of oxygen and carbon dioxide in the baby.
  • Complete blood count, called CBC
  • Platelet count, which is one measure of the blood's clotting ability
  • Blood type
  • Blood cultures for aerobic and anaerobic bacteria to rule out infection
  • Bilirubin
  • Blood glucose
Test results will be within a healthy range for some babies. For others, abnormal results suggest certain health problems or other issues:
  • A low pH (less than 7.25) indicates high levels of acid in the infant's bloodstream. This may occur if the mother or baby does not get enough oxygen during labor. It may also happen if the umbilical cord becomes compressed during delivery.
  • A positive blood culture may show abnormal bacteria in the mother or infant.
  • A high blood glucose level may be present if the mother has diabetes. If so, the baby may have a dramatic drop in his or her blood glucose level after birth. This condition is called hypoglycemia.
A high bilirubin level can be a sign of several health issues, such as:
  • jaundice in the mother. This is a yellowing of the skin caused by too much of the liver protein called bilirubin in the blood.
  • Rh incompatibility, which is a problem with blood compatibility between the baby and the mother
  • Dubin-Johnson syndrome, a condition in which a collection of bilirubin in the baby's liver cells causes jaundice
  • sulfa medicines taken by the mother during pregnancy
  • toxoplasmosis, an infection that causes destructive lesions of the nervous system
  • rubella, also known as German measles, a disease that may cause birth defects in a baby if the mother had it during the first 2 to 3 months of pregnancy
  • hepatitis, an inflammation in the baby's liver
  • cytomegalovirus, known as CMV, an infection that may cause symptoms such as fever, lethargy, and loss of appetite in the baby


Manual of Diagnostic and Laboratory Test, Kathleen Pagana and Timothy Pagana

Tabers Cyclopedic Medical Dictionary, F.A. Davis Company

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