Protocols for testing newborns vary internationally and within countries. Table 2 below summarizes some of the more common protocols.
Table 2. Newborn Serologic Testing 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 mother 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.
