Assessment of Fetomaternal Hemorrhage by Flow Cytometry and Kleihauer-Betke Test in Rh-Negative Pregnancies

Abstract

Objectives: To assess the efficacy of flow cytometry (FC) in the detection and quantification of fetomaternal hemorrhage (FMH) in comparison to the Kleihauer-Betke test (KBT). Methods: 25 unsensitized Rh-negative mothers who had delivered Rh-positive infants were included. Presence of FMH was determined by KBT and FC using FITC-labeled BRAD-3 antibodies. Results: FMH was detected in 19 (76%) patients by FC and 23 (92%) patients by KBT prior to delivery, and in 21 (84%) patients by FC and 23 (92%) patients by KBT after delivery. The mean volume of FMH in the post-delivery samples by KBT and FC were 0.34 ± 0.26 ml (range 0.05–1.2 ml) and 0.37 ± 0.57 ml (range 0.02–2.6 ml) respectively. The volume of post-delivery FMH estimated by KBT and FC correlated well (r = 0.75; ICC α = 0.73). A higher agreement between KBT and FC was seen in the 0.1–0.5 ml range (ĸ = 0.65; p < 0.01). Conclusions: Both manual KBT and FC using FITC-BRAD-3 antibodies show good sensitivity in detecting and quantifying fetal red cells. There is a good correlation between the methods in the 0.1- to 0.5-ml range of FMH.