Basophils, relative percentage (cord blood)

This test measures the proportion of basophils among the white blood cells in a cord blood sample collected at birth. Basophils are a type of granulocyte involved in allergic responses and inflammation, releasing histamine and other mediators when activated.

It is reported as a relative percentage rather than an absolute count and is typically included as part of a complete blood count with differential performed on cord blood. Results are interpreted alongside other white blood cell types to give a picture of the newborn’s immune status at delivery.

The basophil percentage can help your care team understand patterns of immune activity in a newborn when considered with other blood findings and the clinical picture. Unusual proportions may be associated with allergic conditions, certain infections, inflammatory diseases, or bone marrow disorders, although isolated changes are often not specific on their own.

This measurement is commonly obtained automatically with a cord blood panel or when there are concerns about infection, breathing difficulties, jaundice, or hematologic conditions in a newborn. It can also provide context when other white blood cell populations are increased or decreased.

A result slightly outside the usual range can occur because of the stress of labor, timing of cord clamping, or normal newborn adaptation after delivery. Your clinician will interpret the basophil percentage together with the absolute basophil count, other differential results, red blood cell and platelet findings, and any signs or symptoms your baby may have.

If the value seems unexpected in context, your clinician may repeat the test, have a specialist review a blood smear manually, or order additional studies to look for allergy, infection, or rare bone marrow conditions. Most small deviations without symptoms do not indicate a serious problem and simply lead to observation or a follow-up test.