Accuracy of a portable hemoglobinometer (HemoCue) to measure fetal hemoglobin values during in utero transfusion

Objectives: The current recommended treatment for severe fetal anemia is in utero transfusion (IUT). During this procedure, the evaluation of the necessary volume of transfused blood is based on regular measurement of fetal hemoglobin (FHb) concentration. The gold standard measurement is performed in the biology laboratory. A rapid medical test such as HemoCue^® is an effective way to predict FHb concentration. It would reduce the time to obtain results and therefore the procedure duration. To evaluate the accuracy of HemoCue^® to measure FHb during IUT, we compared Hb levels obtained by HemoCue^® and by our biology laboratory.

Methods: This retrospective study involved all pregnant women who had undergone an IUT in the university hospital of Clermont-Ferrand, France, during the period from 1 January 2010 to 6 June 2021. The FHb level was evaluated by two methods, a rapid medical test, HemoCue^®, and a standard method in the biology laboratory.

Results: We obtained 244 pairs of results from HemoCue^® and our laboratory, of 90 IUT procedures. The correlation between the two sets of results was excellent, with Lin's concordance correlation coefficient of 0.979. However, we established that the measurements were not significantly modified by IUT number, puncture time, cause of fetal anemia, estimated fetal weight, gestational age, and delay between two IUT or middle cerebral artery peak systolic velocity values.

Conclusion: Our results allowed to extend the relevance of FHb measurements by HemoCue^® during IUT.