False positive Kleihauer tests and unnecessary administration of anti-D immunoglobulin.

This obstetric case shows two false negative Kleihauer tests and two persistently positive Kleihauer tests leading to unnecessary administration of anti-D immunoglobulin. A diagnosis of hereditary persistence foetal haemoglobin (HPFH) was only confirmed by access to flow cytometry making use of both anti-HbF and anti-D labels. The case highlights the importance of a high index of clinical suspicion for HPFH and the importance of access to flow cytometry estimation of minor RhD red cell populations postnatally in RhD-negative mothers.