Detection of foeto-maternal haemorrhage by flow cytometry

Abstract

Foeto-maternal haemorrhage (FMH) is the passage of foetal red blood cells (RBCs) into the maternal circulation. This may lead to sensitisation in cases when there is Rhesus (Rh) incompatibility between the mother and the foetus. Such sensitization is prevented with the administration of Anti-D to an RhD negative mother bearing an RhD positive foetus. The accurate quantification of FMH is necessary to determine the exact dose of Anti- D prophylaxis administered, in order to prevent sensitization (Austin. E., et al, 2008). This study evaluated 3 assays used in the quantification of FMH that are, the Kleihauer test which is the standard approach in quantifying FMH at Mater Dei Hospital, the Anti- RhD and Anti- HbF flow cytometric (FC) approaches, to determine the most suitable approach for the quantification of FMH. The Anti- HbF assay allows dual fluorescent detection of intracellular Haemoglobin F (HbF) and Carbonic anhydrase (CA), while the Anti- RhD assay allows the identification of RhD positive foetal cells in an RhD negative mother. Statistical analysis of the three assays showed that the Anti- RhD assay exhibited the strongest correlation with the desired foetal percentage, followed by the Kleihauer test and Anti- HbF assay. Results showed good agreement between the Kleihauer test and Anti- RhD assay, indicating that these two methodologies can be used interchangeably. On the other hand, there was poor correlation between the Kleihauer test and Anti- HbF assay. The Anti- RhD assay, being less laborious than the Anti- HbF assay, is relatively easy to introduce as part of the routine diagnostic test as a follow up for positive FMH cases detected by the Kleihauer test. The accurate quantification of FMH will allow clinicians to administer the exact Anti-D dose to patients suffering FMH, therefore resulting in better patient management.