Anti-G evaluations in D- pregnant women determine the need for Rh immune globulin prophylaxis: report of two illustrative cases.

Distinguishing anti-D, anti- C, and anti-G specificities is particularly essential in antenatal cases to ensure proper patient management. The clinical management as well as Rh immune globulin (RhIG) prophylaxis depend on the accurate identification of these distinct antibodies. D- pregnant women with anti-G, but without anti-D, in their serum need RhIG prophylaxis at 28 weeks of gestation, at delivery if the infant is D+, and when clinically indicated to prevent the formation of anti-D and potential hemolytic disease of the fetus and newborn (HDFN). We present two cases in which determining the antibody specificities determined the course of the patient's treatment. In one case, a 30-year-old, gravida-1, para-0 woman with blood group A, D- and with no previous RhIG administration had the presence of anti-D, -C, and -G in her plasma. Because she had already been alloimmunized and developed anti-D, RhIG prophylaxis was not necessary. In another case, a 37-year-old, gravida-2, para-1 woman with blood group A, D- and no prior RhIG administration had anti-C and anti-G in her plasma. Because she was not sensitized to D, she needed RhIG prophylaxis. In conclusion, pregnant women can develop anti-C and/or anti-G in the absence of anti-D. Therefore, studies should be conducted to differentiate anti-D, -C, and -G in pregnant women who are presumptively identified as having anti-D and anti-C when their medical history (RhIG prophylactic therapy) suggests that anti-D may not actually be present. In the absence of anti-D, pregnant women should receive prophylaxis with RhIG to prevent alloimmunization to D. For pregnant women who are already sensitized to D, RhIG prophylaxis is not needed.