RESUMO
OBJECTIVES: This study aimed to determine F cell prevalence in a cohort of maternal and gynaecology specimens using QuikQuant anti-HbF flow cytometry (FC) kit and to investigate if the presence of maternal F cells can lead to fetomaternal haemorrhage (FMH) overestimation. BACKGROUND: The gold standard to estimate FMH is the Kleihauer-Betke test (KBT). The KBT has proved to be insufficiently sensitive to detect low numbers of circulating fetal cells due to the presence of maternal F cells. At present, the prevalence of false positive KBT results due to raised maternal F cell population, defined as >5%, is poorly characterised. METHODS: A total of 120 specimens were tested for the presence of F cells and fetal cells by KBT and anti-HbF FC. The results calculated were compared to determine FMH overestimation. RESULTS: Of our cohort, 32% showed an elevated F cell population, of which 69% (27 of 39) were clinically significant according to KBT (>2 mL FMH). The mean FMH volumes by KBT and anti-HbF FC were 3·90 mL (0·20-35·40 mL) and 4·09 mL (0·20-9·70 mL), respectively. CONCLUSION: The study highlighted that an elevated F cell level could be found in the cohort tested, with an F cell level of >10% causing significant FMH overestimation by KBT.