Detecting fetomaternal hemorrhage after first-trimester abortion with the Kleihauer-Betke test and rise in maternal serum alpha-fetoprotein

OBJECTIVE: To compare the incidence and detect the volume of fetomaternal hemorrhage (FMH) during first-trimester abortion with the Kleihauer-Betke test (KBT) and rise in maternal serum alpha-fetoprotein (AFP). STUDY DESIGN: Blood samples were drawn immediately before and after first-trimester termination of pregnancy in 48 women. AFP was estimated using an enzyme-linked immunosorbent assay technique. Fetal cells were counted using the acid elution technique described by Kleihauer. Volume of FMH with both techniques was calculated using standard formulae. Significant FMH was reported when there was a > 40% rise in AFP or > 0.25 mL bleed detected by KBT. RESULTS: Of the 48 cases studied, 18 (37.5%) showed no indication of FMH by either AFP or KBT. In 30 (62.5%) cases there was evidence of FMH; in 7 (14.6%) this was shown by both AFP and KBT. Another 10 (21%) showed significant changes in AFP concentration only, and 13 (27%) showed abnormal KBT results with stable AFP levels. The incidence of detectable FMH after first-trimester abortion in this series was 35% when assessed by AFP and 42% when assessed by KBT (P > .05). The mean volume of FMH detected by KBT was 0.5+/-0.05 mL and by AFP was 0.01+/-0.02 mL. CONCLUSION: This study showed that AFP and KBT are equally sensitive methods of detecting the incidence of FMH in first-trimester abortion, but concordance between the 2 tests is poor. The volume of FMH detected by KBT and FMH is also significantly different.