Kleihauer Testing and Flow Cytometry. A Comparative Study for Assessment of Feto-Maternal Haemorrhage.

Abstract

The Kleihauer test has been used world-wide for many years to quantify feto-maternal haemorhage, and to ensure that an appropriate dose of anti-D Immunoglobulin (anti-D Ig) is administered both ante-natally and postnatally to RhD negative women to prevent Rh alloimmunisation. Although apparently a simple test to perform, recent reports have suggested that unless meticulous attention is paid to both technique and interpretation, the accuracy of the test cannot be guaranteed. It is suggested that it should be replaced with a flow cytometric test for the presence of fetal RhD positive cells which would give more relevant and accurate results. Flow cytometers are not, however, available to all laboratories performing estimations of feto-matemal haemorrhage (FMH). This study was undertaken to assess the comparability of results obtained using a standardised Kleihauer technique with results obtained using a variety of techniques within hospital laboratories and with flow cytometry. A total of 957 samples were analysed, referring hospitals initially performing a routine Kleihauer test and then forwarding the same sample to the Mersey Transfusion Centre where a standardised Kleihauer test and flow cytometric analysis of FMH were performed. Our results showed that there is variation in Kleihauer results, even when the same sample is used, particularly in quantifying an FMH for which additional anti-D Ig may be required. The tendency however, appears to be to over-estimate the size of FMH and administer unnecessary anti-D Ig. Our results suggest that if careful attention is paid to performing a standardised Kleihauer test, then it is of value in estimating the size of FMH, and that flow cytometry may be of additional value for cases in which the Kleihauer result is equivocal or indicates that a large FMH has occurred which requires the administration of additional anti-D Ig.