Rh Immune Globulin After the Transfusion of RhD-Positive Blood in a Patient with a Partial D Antigen

Patients with a serologic weak D phenotype may demonstrate variable RhD expression. We present a case in which clinical management would have been simplified if RHD genotyping had been performed previously.

A 33-year-old patient, G11P4155, presented with an incomplete miscarriage and was transfused RhD-positive packed red blood cells after typing RhD-positive. The patient had been historically typed RhD-negative by a different testing methodology. Indirect antiglobulin testing was performed, which revealed a serologic weak D phenotype. The patient was given 9,600 micrograms of Rh immune globulin. Molecular testing revealed a partial D antigen, which was originally thought to be at risk for alloimmunization; however, this has since been disproven.

Although not yet universal practice, prenatal RHD genotyping for partial D antigen could have prevented the characterization of this patient as RhD-positive at the time of transfusion.