In fetuses affected by red blood cell (RBC) alloimmunization due to hemolytic disease of the fetus and newborn (HDFN), the mainstay of treatment comprises serial intrauterine infusions (IUTs), which typically involve utilization of the Kleihauer-Betke (KB) stain. The use of hemoglobin (Hgb) electrophoresis testing, however, may be quicker and associated with a reduced cost of analysis compared with the KB stain, according to findings from a prospective study published in the American Journal of Obstetrics and Gynecology.
The researchers sought to establish the association between the traditional KB staining and fetal Hgb electrophoresis testing. The cohort study evaluated all alloimmunized singleton pregnancies in which IUT was performed between Jan. 1, 2021, and July 1, 2023.
The investigators obtained maternal and fetal features from all participants, as well as their indication for IUT. At the end of each transfusion, a final fetal blood sample was collected, which was sent for KB staining and Hgb electrophoresis testing.
The primary study outcome was the evaluation of these parameters with respect to their ability to predict replacement of the fetal circulating RBC population with donor cells.
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There were a total of 56 IUTs performed in 16 different patients. A total of 39 final KB stain values were obtained, which were compared with 30 final Hgb electrophoresis values.
Results of the study revealed that Hgb electrophoresis testing vs KB staining demonstrated a statistically significant association (95% CI, 0.61–0.76; P <.001). This finding remained the same when the association at each IUT was evaluated. In fact, results of the final KB stain value and Hgb electrophoresis value decreased significantly with each transfusion (P =.03).
At the time of the third transfusion, a predominance of adult donor blood was observed for both of the laboratory indices. In other words, both techniques exhibited a similar ability to determine bone marrow (BM) suppression in fetuses that are undergoing IUT.
“Fetal Hgb electrophoresis obtained at the time of IUT demonstrates a significant correlation with the traditional KB stain,” the authors explained. “Given the increased cost, training, and time necessary to obtain a KB stain[,] substitution for an automated Hgb electrophoresis should be considered with comparable results,” they concluded.
