Detection of transplacental hemorrhage during the last trimester of pregnancy

The scientific basis of antenatal prophylaxis

“…The Prevalence of FMH increases at the end of pregnancy. Large FMH in the last trimester, >5 ml fetal blood, was observed in in o.5% women 1 , and >10 ml in 0.27% of women 9 . These analyses from only two samples taken during each pregnancy almost certainly underestimate the true incidence throughout pregnancy, especially in the third trimester, when prophylactic anti‐D would be expected to result in clearance of some RhD positive fetal RBC from the maternal circulation.…”

“…Two main concerns exist ‐ the risk of ‘augmentation’, or enhanced anti‐D immunisation, and the effect of passive anti‐D on the fetus. In theory, the existence of low levels of passive anti‐D in the maternal circulation on exposure to RhD positive RBC could result in enhancement of a primary immune response, as has been observed in experimental models 1,3 ‐ the opposite of what is intended. In practice, this has not been observed during trials 5 , and the experimental data in immunised volunteers are conflicting 14,15 .…”

“…treating both arms of the study on an ‘intention to treat’ basis, otherwise there will be an overestimate of efficacy under routine practice conditions. Initial safety concerns about effects of antenatal anti‐D on the fetus have not been confirmed in practice. Options Although there is only one randomised controlled clinical trial (with small numbers) demonstrating a further reduction in alloimmunisation following antenatal administration of anti‐D 1 meriting a grade A recommendation (see appendix II), the total body of evidence of efficiency is compelling. Whilst two doses of 300μg are effective, this is no more so than the single dose in practice, and as it requires considerably more anti‐D immunoglobulin, it is probably not cost effective.…”

“…Options Although there is only one randomised controlled clinical trial (with small numbers) demonstrating a further reduction in alloimmunisation following antenatal administration of anti‐D 1 meriting a grade A recommendation (see appendix II), the total body of evidence of efficiency is compelling. Whilst two doses of 300μg are effective, this is no more so than the single dose in practice, and as it requires considerably more anti‐D immunoglobulin, it is probably not cost effective.…”

Immunohaematological and Biochemical Characteristics in Rh-D Haemolytic Disease of Newborn

“…0.40% -5.8% at 28 -30 weeks and 1.84% -7.0% at 30 -39 weeks. 16 Woodrow and Finn demonstrated a relationship between the number of foetal red cells in maternal circulation at the time of delivery and the chance of anti-D appearance thereafter. 17 In an analysis by Boorman et al, the titre of anti-D was increased after delivery and a peak was reached by 1 -3 weeks.…”