Alternative Names cord blood test, cord blood sampling
Definition 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 labour 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.
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
respiratory status (pH, pCO2, pO2). pH tells how the lungs are functioning in using oxygen and releasing carbon dioxide. pO2 and pCO2 tell what the pressure levels are of oxygen and carbon dioxide in the baby.
Test results will be normal for some babies. For others, abnormal results suggest certain health problems or other issues.
A low pH (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 labour. 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 glucose, or blood sugar, level may be present if the mother has diabetes. If so, the baby may have a dramatic drop in his or her blood sugar level after the birth. This condition is called hypoglycaemia.
High bilirubin levels 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
sulphur medications taken by the mother during pregnancy
toxoplasmosis, an infection that causes destructive lesions of the nervous system
rubella, a disease that may cause birth defects in a baby if the mother had it during the first 2 to 3 months of pregnancy
Author: Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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