Justification for requesting routine antibody identification and titer on women who have received RhIG during pregnancy 

A supervisor from a blood center in the Midwest has received several requests for titrations on samples from patients who have received Rh Immune Globulin (RhIG). The samples received are requests for antibody identification and titer on sequential samples during gestation for patients after they have received RhIG. The clinicians involved were interviewed and all responded that they ordered these titer investigations routinely while a patient is receiving RhIG.  The most recent physician was holding the administration of additional RhIG until receiving the titer result to determine if the patient required an additional dose at 27 weeks.

Does anyone have any advice or experience with such requests? Is there a valid reason to justify routine orders like this after a patient has received RhIG?

The following comment has been received.

ADDENDA April 14, 2004

1. W. John Judd, FIBMS, MIBiol, Professor of Immunohematology at the University of Michigan Medical Center states that the only scenario in which they might titrate the serum of a woman who has received RhIG prophylaxis at 26-28 weeks’ is if, subsequent to RhIG administration, they find that the antibody screen is positive on a sample taken before RhIG was given. This can occur since his facility does not withhold the RhIG while waiting for the antibody screen results. They will then look for an increasing titer, suggestive of active immunity, and manage the pregnancy accordingly. He can recall such a scenario arising once during his 30 years at the University of Michigan.
   
   He concludes, "To request such testing on a routine basis lacks medical and scientific foundation. There is a false notion among some obstetricians that the absence of anti-D post-injection means that insufficient RhIG has been administered. On the contrary, the presence of anti-D in the maternal serum does not mean that the woman is adequately protected. See: Ness PM, Salamon JL. The failure of postinjection Rh immune globulin titers to detect large fetal-maternal hemorrhages. Am J Clin Pathol 1986;85:604-6."

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