Flow cytometry in diagnosis and management of large fetomaternal haemorrhage

To evaluate an indirect immunofluorescence flow cytometry technique in a series of patients with large fetomaternal haemorrhage (FMH).

Patient samples identified by Kleihauer testing in local laboratories as having FMH > 4 ml were sent for flow cytometric analysis. In a proportion of cases the mothers received anti-D immunoglobulin prophylaxis according to the flow cytometer estimate of FMH volume.

Forty three cases of FMH were studied prospectively. The correlation between Kleihauer and flow cytometry results was poor. In 38 (88%) cases the size of FMH quantitated by flow cytometry was lower than that estimated using the Kleihauer technique. In 13 (30%) cases no Rh D immunoglobulin positive cells were detected by flow cytometry. Centralised review of the original Kleihauer films using a calibrated microscope resulted in improved, but still suboptimal correlation with flow cytometry results. In 15 cases anti-D immunoglobulin was given according to the flow cytometer estimation of FMH size, resulting in a 58% reduction in the amount of anti-D immunoglobulin given. None of the patients were immunised when tested six months later.

Flow cytometry is helpful for the accurate quantitation and management of patients with large FMH and in cases where the presence of maternal haemoglobin F containing cells renders the Kleihauer technique inaccurate. Worthwhile reductions in the use of anti-D immunoglobulin can be achieved.