Cord blood testing
Cord blood refers to a sample of blood collected from the umbilical cord when a baby is born. The umbilical cord is the cord connecting the baby to the mother's womb.
This article focuses on cord blood testing done to evaluate a newborn's health.
How the Test is Performed
Immediately after the birth of your baby, the umbilical cord is clamped and cut. If cord blood is to be drawn, another clamp is placed 8 to 10 inches away from the first, then the isolated section is cut and a blood sample is collected into a specimen tube.
How to Prepare for the Test
No special preparation is necessary for this test.
How the Test Will Feel
You will not feel anything beyond the normal birthing process.
Why the Test is Performed
Cord blood testing is done to determine the following:
- Bilirubin levels
- Blood culture (if an infection is suspected)
- Blood gases, to evaluate the oxygen, carbon dioxide, and pH levels
- Blood sugar level
- Blood type and Rh
- Complete blood count (CBC)
- Platelet count
Normal values mean that all items evaluated are within normal range.
What Abnormal Results Mean
A low pH (less than 7.04 to 7.10) means there are higher levels of acids in the baby's blood. This might occur when the baby does not get enough oxygen during labor. One reason for this could be that the umbilical cord was compressed during labor or delivery.
A blood culture that is positive for bacteria measn you have a blood infection (septicemia).
High levels of blood sugar (glucose) in the cord blood may be found if the mother has diabetes. The newborn will be watched for hypoglycemia (low blood sugar) after delivery.
High levels of bilirubin could be due to infections that the baby gets before birth, including:
- Congenital CMV
- Congenital hepatitis
- Congenital rubella
- Congenital toxoplasmosis
Other possible causes include:
- Dubin-Johnson syndrome
- Jaundice in the mother
- Mother taking sulfa drugs during pregnancy
- Rh incompatibility
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
Most hospitals routinely collect cord blood for testing at birth, since it is relatively convenient and the only time possible to collect such blood. Besides cord blood testing, cord blood can be used to treat certain types of bone marrow-related cancers. Some parents may choose to save (bank) their child's cord blood for this and other, future medical purposes.
Cord blood banking for personal use is done by private companies, which charge for the service. Cord blood can also be donated to your local blood bank for use by others as needed to treat leukemia and other cancers.
American Academy of Pediatrics Section on Hematology/Oncology, American Academy of Pediatrics Section on Allergy/Immunology, Lubin BH, Shearer WT. Cord blood banking for potential future transplantation. Pediatrics 2007;119(1):165-170.
Carlo WA. The fetus. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 90.
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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