Laboratory Test Reference Guide

For Confirmatory testing

The FMH Anti-HbF method is automatically added as a confirmatory test for where a positive Kleihauer-Betke test shows at least > 4mls of fetal bleed.

Monitoring clearance of foetal red cells

Follow up testing is recommended to monitor for adequate clearance of fetal red cells for FMH ≥ 6 mL and provide guidance for administration of additional RhD Ig.

Refrigerate sample if not tested within 4 hours post collection

Sample can be tested if stored at 4°C for up to 72 hours

The Flow Cytometry Test Method for Fetomaternal Hemorrhage (FMH) is used to quantify fetal red blood cells (RBCs) in maternal blood, primarily after delivery, trauma, or procedures (like amniocentesis), to determine if anti-D prophylaxis is needed in RhD-negative mothers.

References

Guidelines for the laboratory estimation of fetomaternal haemorrhage (2nd edition September 2021)

CLSI H52-A2: Quantitation of Fetal Hemoglobin in Red Blood Cells by Flow Cytometry