Protective levels of anti-D prophylaxis at delivery
During the period Oct 2010-Oct 2012 type-and-screen were requested from the delivery ward in 4280 RhD negative women carrying an RHDpositive fetus. According to clinical routine, RAADP 1250 IU (Rhesonativ®, Octapharma, AG, Austria) had been administered in gestational week 28-29. In 876 cases (20.5%) the type-and-screen result was negative, i.e. anti-D was not detectable at delivery, which corresponds to an anti-D concentration less than 10 IU/L (2 µg/L). Information of gestation age at delivery was not available.
Anti-D concentration before and after administration of anti-D prophylaxis at 38 weeks of pregnancy The mean anti-D concentration at inclusion in the prospective interventional study was 14±11 IU/L [mean ± SD, n=39] in gestational week 38±1, Fig 1. In 17 of the 39 (44%) women the anti-D concentration was below LOD in the routine antibody screening, 10 IU/L (2 µg/L), Fig. 1. In 7/39 (18%) the level was below LOD in the anti-D quantification assay, 1 IU/L (0,2 µg/L). The anti-D concentration measured one week after administration of prophylaxis was 75 ± 47 IU/L [mean ± SD]. The increase of anti-D was 66 ± 45 IU/L [mean ± SD], and showed a significant correlation (p = 0.0118) with body mass index, Fig 2.