The frequency of anti‐C + anti‐G in the absence of anti‐D in alloimmunized pregnancies

Anti-D+C are often initially identified in sera from alloimmunized women. Anti-G may be present in these samples, mimicking anti-D+C, and therefore the differentiation of anti-D, -C and -G may be important. Sera from 27 alloimmunized women, initially identified as containing anti-D + anti-C, were analysed by adsorption/elution studies in the presence of polyethylene glycol (PEG) using R(0)r (D+C-G+) and r'r(D-C+G+) red blood cells (RBC). Additionally, 15/27 samples were tested by adsorption in the presence of PEG and subsequently warm elution, using rGr (D-C-G+) RBC. Anti-G + anti-C, without anti-D, were identified in 4/27 samples (14.8%) and none of the newborn children needed postpartum treatment. The combination of D+G, D+C and D+C+G antibodies occurred in 25.9%, 11.1% and 48.1% of the women, respectively. Overall, anti-G was detected in 24/27 samples (88.9%). Pregnant women shown to have anti-G+C but not anti-D should receive Rh immune globulin. Additionally, the finding of apparent anti-D+C during pregnancy in D-negative spouses may lead to paternity testing and therefore a correct antibody identification is necessary.