Detecting fetomaternal hemorrhage: a comparison of five methods

Area of Science:

• Immunology
• Hematology
• Clinical Chemistry

Background:

• Postpartum Rh immune globulin administration requires precise detection of fetomaternal hemorrhage (FMH).
• Microscopic Du test (micro Du), PEG-enhanced Du test (PEG Du), and flow cytometry (FC) are emerging methods for FMH assessment.

Purpose of the Study:

• To evaluate the sensitivity and accuracy of qualitative and quantitative methods for detecting FMH.
• To compare PEG Du and FC methods for FMH quantitation.

Main Methods:

• In vitro studies involved serial dilutions of D+ cord cells in D- adult cells.
• Qualitative methods: micro Du, rosette test, PEG Du.
• Quantitative methods: acid elution, FC.
• Analysis of 26 postpartum samples.

Main Results:

• Micro Du showed 20% false negatives at 0.5% fetal cells; PEG Du offered minimal improvement.
• The rosette test was most sensitive, detecting fetal cells at ≥0.25%.
• FC and acid elution demonstrated strong correlation (r=0.99 and r=0.96) between measured and expected FMH quantities.

Conclusions:

• Flow cytometry (FC) is a reliable and reproducible quantitative method for assessing fetomaternal hemorrhage (FMH).
• FC provides an objective alternative to acid elution for FMH quantitation.
• Accurate FMH detection is vital for appropriate Rh immune globulin prophylaxis.