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Newborn Serologic Testing Protocols

Protocols for testing newborns vary internationally and within countries. The table below summarizes some of the more common protocols.

Scenario

Typical Newborn Testing Protocol

Comments

Mother is D-negative with no unexpected antibodies

Newborn is tested at delivery for:

  • ABO and Rh
  • Test for weak D (mandatory) if initial Rh typing appears to be D-negative
  • Direct antiglobulin test (DAT)*

A positive DAT does not always mean that the newborn has clinically significant hemolysis.

  • A positive DAT commonly occurs due to ABO incompatibility, yet infants seldom require treatment.
  • Infants born to mothers who received antenatal RhIg sometimes have a positive DAT that does not cause clinically relevant hemolysis.

Mother is Rh positive and a blood group other than group O

  • Routine testing not performed
  • Cord blood retained for a specified period of time (e.g., seven days) in the event that the mother has an unexpected antibody at delivery or the newborn develops signs of red cell hemolysis.
  • Routine testing would result in many positive DATs due to ABO incompatibility- not clinically significant.

Mother is group O Rh positive

Newborn is tested- especially important if women and their infants are discharged within 24 hours since hyperbilirubinemia due to ABO HDFN may develop later.
  • Optional only if there is appropriate surveillance and risk assessment before discharge and provided there is follow-up (American Academy of Pediatrics).

*Policies for DAT testing of newborns whose mothers have received antenatal RhIg vary internationally. For example, the British Committee for Standards in Haematology guidelines state that a DAT should not be performed on cord blood routinely since in some cases it may be positive due to antenatal RhIg prophylaxis. A DAT is recommended only if HDFN is suspected because of a low cord blood hemoglobin or the presence of unexpected maternal antibodies. However in North America, DATs are always performed on infants born to Rh negative mothers who are RhIg candidates.