Severe hemolytic disease of fetus and newborn caused by red blood cell antibodies undetected at first‐trimester screening (CME)

BACKGROUND: The objective was to determine clinical consequences of anti-D and non-D antibodies undetected at first-trimester screening for infant or fetus. STUDY DESIGN AND METHODS: This retrospective cohort study included all pregnant women with red blood cell (RBC) antibodies who were tested between 1993 and 2008. Data were obtained from the forms for tracking immunization at the transfusion department. Each form was analyzed for three data sets: the order of screening at which the antibodies were detected (initial or repeated screening), the order of pregnancy (first pregnancy or higher), and whether the antibodies caused severe hemolytic disease of fetus and newborn (HDFN). RESULTS: In D– women, anti-D was detected in 1.3% of cases. The anti-D was undetected in 72 (37%) cases on the first-trimester screening, of which eight cases were complicated by severe HDFN. In this group, three patients were primigravidae. An overall non-D incidence of 0.2% was observed. In 16 cases, non-D were undetected on the first-trimester screening (10 anti-c, two anti-E, two anti-C, one anti-S, and one case of anti-Rh17). Non-D antibodies undetected on initial screening caused 11 cases of severe HDFN (27% of all severe non-D HDFN). Ten of them were in multiparous women. Seven of 11 cases with severe HDFN that were missed were caused by anti-c. CONCLUSION: The third-trimester screening may detect RBC antibodies that were not present or detected on the first-trimester screening. Such screening may be especially relevant in D+ multiparous women due to the risk of HDFN.