Flow cytometric assessment of feto‐maternal hemorrhage; a comparison with Betke–Kleihauer

OBJECTIVES: Assessing the number of fetal cells in the maternal circulation quantifies the volume of feto-maternal hemorrhage, enhancing the ability to provide effective prevention of Rhesus (Rh) allommunization and appropriate fetal surveillance in cases of significant feto-maternal hemorrhage. METHODS: Having developed a standard curve with maternal samples spiked with known volumes of fetal red blood cells, we used a flow cytometric method using fluorescent labeled antihemoglobin F to quantitate fetal cells in the maternal circulatory system in two groups of women undergoing chorionic villus sampling (CVS), by either biopsy forceps or cannula aspiration (n = 170 women). We compared these results with the gold standard, the Betke-Kleihauer test. RESULTS: Our results show good correlation between the flow cytometric method and the traditional Betke-Kleihauer method for fetal red cell quantitation (r(2) = 0.99). Fetal red blood cells were identified in 10 women by the Betke-Kleihauer method, and in 26 women by flow cytometry. CVS was not associated with an increase in feto-maternal hemorrhage. CONCLUSION: Flow cytometry was both more sensitive and more timely for the quantitation of feto-maternal hemorrhage than was Betke-Kleihauer.