Anti-G antibody mimics the reactivity pattern of coexistent anti-D and anti-C. Differentiating between the two is significant in antenatal females where the decision to administer RhD prophylaxis is based on the presence or absence of anti-D antibody. The aim of reporting this serological challenge is to emphasize the need for phenotyping red cells for sourcing appropriate in house red cell reagents and to help transfusion services sharpen problem-solving skills. A 26-year-old pregnant female with a complicated obstetric history and a positive indirect antiglobulin test presented to the hospital for antenatal assessment at 24 weeks. A positive antibody screen warranted identification of the implicating antibodies. Since identification was suggestive of multiple alloantibodies whose specificities could not be confirmed, step-wise sequential adsorption and elution was required. Anti-D, anti-C, and anti-E antibodies were identified in patient plasma with titers of 1024, 4, and 32, respectively. The absence of anti-G was also confirmed. Multiple alloantibodies can pose a challenge to transfusion services. However, with the help of select cells, phenotyping, adsorption elution studies, and phenotyped donor units; solving complex serological cases can be accomplished.

Anti-G is commonly present with anti-D and anti-C and can confuse serological investigations. The differentiation of anti-G from anti-D and anti-C is particularly essential for the accurate diagnosis of hemolytic disease of the fetus and newborn (HDFN) and appropriate administration of anti-D immunoglobulin prophylaxis in Rhesus (Rh) negative women. We reported a rare case of anti-G together with anti-D and anti-C in a pregnant woman and her female neonate. The titers of IgG anti-D, anti-C, and anti-G in the woman were 256, 128, and 32, respectively. While the titers of IgG anti-D, anti-C, and anti-G in the neonate were 16, 8, and 4, respectively. The neonate experienced mild HDFN and only received phototherapy during hospitalization. This report discusses the diagnostic strategy and clinical significance of differentiating anti-G from anti-D and anti-C.

The G antigen of Rh blood group system is present in almost all D-positive or C-positive red cells but absent from red cells lacking D and C antigens. The differentiation of anti-D and anti-C from anti-G is not necessary for routine transfusion; however, during pregnancy, it is important because anti-G can masquerade as anti-D and anti-C with initial antibody testing. The false presence of anti-D will exclude the patient from receiving anti-D immunoglobulin (RhIG) when the patient actually is a candidate for RhIG prophylaxis. Moreover, patients with positive anti-D or anti-G are at risk of developing hemolytic disease of the fetus and newborn and need close monitoring. Thus, proper identification allows the clinicians to manage patients properly. This case report highlights a rare case of anti-G together with anti-D and anti-C in a pregnant woman. This report disseminates knowledge on identification of anti-G and its importance in pregnant women.