Multicenter clinical experience with flow cytometric method for fetomaternal hemorrhage detection

Area of Science:

• Hematology
• Immunology
• Clinical Diagnostics

Background:

• Accurate enumeration of fetal red blood cells (RBCs) is critical for managing fetomaternal hemorrhage (FMH), especially in Rh-incompatible pregnancies.
• Fetomaternal hemorrhage (FMH) can lead to significant fetal complications, necessitating reliable diagnostic methods.

Purpose of the Study:

• To evaluate the efficacy and superiority of the flow cytometric method (FCM) using an anti-hemoglobin F (HbF) antibody compared to the manual Kleihauer-Betke (KB) test for detecting fetal RBCs in maternal circulation.
• To assess the clinical utility and transportability of the FCM method across multiple institutions.

Main Methods:

• Multi-institutional evaluation of the flow cytometric method (FCM) for fetal RBC detection using anti-hemoglobin F (HbF) monoclonal antibody.
• Comparison of FCM results with the manual Kleihauer-Betke (KB) test, including analysis of fluorescence intensity and forward light scatter.
• Assessment of test transportability through inter-laboratory comparisons and review of College of American Pathologists survey data.

Main Results:

• During 1997-2001, 5.5% of patients had detectable fetal RBCs, with 1.7% having >30 mL of fetal blood (large FMH).
• A high mortality rate of 64% was observed in infants with large FMH.
• FCM demonstrated significant differences in anti-HbF staining intensity and forward light scatter between fetal and adult RBCs, confirming its specificity and sensitivity. FCM proved superior to the KB test.

Conclusions:

• Flow cytometric method (FCM) is a simpler, more objective, and precise alternative to the Kleihauer-Betke (KB) method for clinical detection of fetomaternal hemorrhage (FMH).
• The high mortality associated with large FMH underscores the need for laboratories to adopt the more robust FCM method over the KB test for improved patient outcomes.