Detection of significant fetomaternal hemorrhage by flow cytometry

Article Outline

• Objective
• Study design
• Results
• Conclusion
• Copyright

Back to Article Outline

Objective 

Significant sub-acute and chronic fetomaternal hemorrhage (FMH) may have serious implication on the fetus and the neonate. The accuracy of flow cytometry for the detection of fetomaternal hemorrhage (FMH) is limited by false positive staining of non-fetal cells. We sought to assess the incidence of the “background” events, and to define the minimal amount of FMH that can be reliably detected by this technique.

Back to Article Outline

Study design 

Blood samples from 12 pregnant women, 12 non-pregnant adults and 8 cord blood samples were collected. RBC were fixed, permeabilized and stained with fluorescent-conjugated monoclonal antibodies to fetal hemoglobin (HbF). Cellular fluorescence, i.e. Hb content, was analyzed by a FACScaliburR flow cytometer.

Back to Article Outline

Results 

RBC were grouped into three “Zones” according to their fluorescence intensity following staining with anti-HbF antibodies. Zone A: which included fetal RBC with high HbF content, was delineated using RBC of neonatal cord blood; Zone B: adult F-cells with low HbF-content, was determined using blood of beta-thalassemia patients, and Zone C: non HbF-containing cells, was determined using blood of non-pregnant adults. Blood samples of non-pregnant adults (male and post-menopausal women, (n=12) produced 0.03% (0-0.12%) events in Zone A, and blood samples of pregnant women (n=12) produced 0.02% (0-0.08%) events in Zone A. No significant difference between these groups was noticed. mean results of both groups were significantly lower (P < .001) than 0.6% events of fetal RBC (approx. 30 mL blood) which is assumed to be of clinical significance.

Back to Article Outline

Conclusion 

Flow cytometry is highly specific for the detection of significant sub-acute and chronic FMH and may improve the treatment of fetuses and neonates at risk.