Alloimmunization in a Rhesus (Rh) D-Negative Pregnant Woman With an Uncommon Rh Phenotype: A Case Report

Rhesus (Rh) alloimmunization remains a critical concern in obstetrics, particularly in RhD-negative pregnant women who have not received postpartum Rh immunoglobulin (RhIg) prophylaxis. This report describes the case of a 19-year-old pregnant woman in her second pregnancy who had no documented administration of anti-D prophylaxis after her first childbirth. During routine screening at 28 weeks of gestation, her Indirect Coombs Test (ICT) showed strong positivity (3+), with an anti-D antibody titer of 1:128. Antibody identification confirmed anti-D specificity. Further immunohematological evaluation revealed that the patient had blood group B negative and an uncommon dCe/dce (also known as r'r) Rh phenotype, lacking D and E antigens. Though the fetus was at risk for hemolytic disease of the fetus and newborn (HDFN), there was no need for intrauterine transfusion during the pregnancy. This case highlights the importance of routine antenatal antibody screening, awareness of Rh phenotypes, and timely prophylactic measures to prevent Rh alloimmunization. Comprehensive monitoring and genotype-informed transfusion planning are especially crucial in resource-limited settings.