Fetal-Maternal Hemorrhage Detection in Ontario

Abstract

The results from fetal-maternal hemorrhage (FMH) detection and quantitation external quality assessment surveys conducted in Ontario indicate that the rosette test had a sensitivity and specificity for an FMH of more than 10 mL of 1.0 and 0.75, respectively, compared with 0.96 and 0.92, respectively, for acid elution. With FMH quantitation, the percentage error of the mean from the target FMH was 20% or more in 7 of 8 surveys, and coefficients of variation ranged from 39.5% to 71.8%. Inadequate Rh o (D) immune globulin prophylaxis could have occurred in 19.4% of the challenges with an FMH of more than 10 mL. The rosette and acid elution techniques are both effective for the detection or exclusion of FMH, but acid elution lacks adequate accuracy and precision for reliable FMH quantitation. Furthermore, a strategy of prescribing an extra 1,500-IU Rh o (D) immune globulin dose, in addition to the dose required to treat the volume of fetal blood detected, is an effective strategy to overcome the limitations of FMH quantitation by acid elution. Hemolytic disease of the newborn (HDN) is the result of maternal antibodies causing destruction of antigen-positive erythrocytes in the fetus. The most serious form of HDN is caused by maternal alloantibodies directed against the D antigen of the Rh blood group system. In this scenario, Rh– mothers are alloimmunized during a previous pregnancy with an Rh+ fetus. HDN occurs in subsequent pregnancies involving an Rh+ fetus when maternal anti-D crosses the