Identifying ABO incompatibility in newborns: selective vs automatic testing

Two approaches to identifying blood group (ABO) incompatibility in infants have been suggested. The routine approach is to automatically perform blood type and direct antiglobulin tests on every infant born to a mother with type O blood. The selective approach is to test only significantly jaundiced infants.

One hundred thirteen infants of mothers with type O blood were tested automatically and 188 other infants were tested selectively. Charts of the infants were reviewed for jaundice recognition and management.

Jaundice recognition and management and mean peak bilirubin levels did not differ significantly between the two groups. However, three of the infants who were tested selectively had bilirubin levels above 342 mumol/L (20 mg/dL). Two infants were readmitted for phototherapy despite automatically having had their cord blood tested. All infants requiring phototherapy were clinically jaundiced before 48 hours of age.

Selective cord blood testing was found to be a reasonable, less expensive alternative to routine testing. However, in clinical settings in which newborns are often discharged before the third day of life, automatic cord blood testing may be preferable. All infants discharged before 48 hours of age need close clinical follow-up regardless of the testing protocol used.