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Complete Blood Count
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Currently under review
Pending specialist review and validation.
RDW in cord blood measures how much variation there is in the size of your baby's red blood cells. The sample is taken from the umbilical cord at birth, often as part of a complete blood count. RDW is calculated by the analyzer based on the spread of cell sizes and is reported as a percentage using a coefficient of variation.
A higher RDW means there is more mix of small and large red cells, and a lower RDW means the cells are more uniform. On its own, RDW does not diagnose a condition, but it helps your baby's clinician interpret other red cell measures such as the mean cell volume and hemoglobin.
Clinicians use cord blood RDW to screen for or support the evaluation of conditions that affect red blood cell production or survival around the time of birth. It can help flag possible iron deficiency, blood loss, hemolysis, or inherited red cell disorders, and it can assist in distinguishing between different patterns of anemia.
Cord blood results provide a baseline for your newborn. When combined with other parts of the complete blood count and clinical findings, RDW helps guide decisions about monitoring, feeding and iron needs, and whether further tests are needed.
If RDW is higher than expected, it usually means there is a wider mix of red cell sizes, which can occur when new cells are being released after blood loss, when iron supply is limited, or when red cells are breaking down faster than they are replaced. If RDW is lower or very uniform, it generally indicates a narrow size distribution, which is less commonly a concern by itself.
Your baby's clinician will look at RDW together with the mean cell volume, hemoglobin, reticulocyte count, bilirubin, and direct antiglobulin test when jaundice or anemia is suspected. Depending on the overall picture, follow up may include repeating the complete blood count after a short interval, checking iron studies or screening for inherited conditions, or simply routine observation. Ask your care team how these findings fit with your baby's feeding, growth, and any symptoms.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
When the cord blood is collected and how the tube is handled can change RDW. Clotting, excess anticoagulant, or hemolysis can skew the analyzer's size distribution.
Normal shifts in red cell production after birth and prematurity can influence RDW. Preterm or growth-restricted infants often have different patterns than term infants.
Maternal iron deficiency, diabetes, or blood group incompatibility can affect the baby's red cells and may raise RDW through altered production or hemolysis.
Intrauterine transfusion, exchange transfusion, or transfusion soon after birth introduces donor cells with different sizes, which can temporarily change RDW.
Limited iron stores, infection, or inflammation can alter red cell production and maturation, affecting the spread of cell sizes seen in RDW.
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