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Objective Mainstay therapy for fetuses affected by maternal red cell alloimmunization is serial intrauterine transfusion (IUT). Testing to determine when fetal red cells have been replaced with donor cells historically involves the use of the Kleihauer–Betke (KB) test. Hemoglobin (Hgb) electrophoresis testing may be more rapid with a reduced cost of analysis. We aimed to determine the correlation between fetal Hgb electrophoresis versus the traditional KB test.

Study Design This is a retrospective analysis of all alloimmunized singleton pregnancies undergoing IUT between January 1, 2021, and July 1, 2023. Maternal and fetal characteristics were collected along with the indication for IUT. A final fetal blood sample was obtained at the conclusion of each transfusion and sent for KB testing and Hgb electrophoresis. The primary outcome was the assessment of these parameters in their ability to predict the replacement of the fetal circulating red cell population with donor cells. Linear regression analysis and repeated measures analysis of variance were performed, and p-values less than 0.05 were considered significant.

Results A total of 56 IUTs were performed in 16 patients. There were 39 (69.6%) final KB test values collected and compared with 30 (53.6%) final Hgb electrophoresis values. Hgb electrophoresis when compared with the KB test demonstrated a significant correlation (R 2 = 0.93; 95% confidence interval, 0.61–0.76; p < 0.001). This same finding held true when examining the correlation at each individual IUT as well. The final KB test and Hgb electrophoresis values significantly decreased with each transfusion (p = 0.003). A predominance of adult donor blood was noted by the third transfusion for both laboratory indices.

Conclusion Fetal Hgb electrophoresis obtained at the time of IUT demonstrates a significant correlation with the traditional KB test.

Key Points

Fetal Hgb electrophoresis following IUT is underexplored

Hgb electrophoresis is an automated evaluation

The traditional KB test is a manual evaluation

These two tests demonstrate significant correlation

Keywords intrauterine transfusion - hemolytic disease of the fetus and newborn - hemoglobin electrophoresis - Kleihauer–Betke test Note

Presented as a poster at the 44th annual meeting of the Society for Maternal-Fetal Medicine, National Harbor, MD, February 14, 2024.

Publication History

Received: 24 January 2024

Accepted: 27 May 2024

Accepted Manuscript online:
28 May 2024

Article published online:
18 June 2024

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