Fetal Hemoglobin Detection by Flow Cytometry
Clinical Significance:
Measurement of fetal cells has traditionally been
performed based on the Kleihauer-Betke technique. This is a slide-based
microscopic counting method of blood smears, which is laborious and suffers
from lack of sensitivity (0.5% Fetal cells, approximately 25ml fetal bleed),
subjectivity and precision (CV 50-100%).
Flow cytometry is capable of both high
sensitivity of detection (0.01%) and rapid cell-by-cell analysis. Using
antibodies to HbF allows for a broad application to various clinical
situations. Moreover, the quantitative nature of flow cytometric analysis
permits the distinction of true fetal cells, which contain HbF as the major
form of Hb, from maternal circulating F-cells that have lower cellular HbF
content. This is particularly applicable for individuals with hereditary
persistence of HbF or various hemoglobinopathies.
The flow cytometric method for the assessment
of fetal-maternal hemorrhage (FMH) is based on the detection of HbF positive
fetal cells in order to:
- determine the dosage of Rh immune globulin required to
prevent Rh sensitization of an Rh negative mother
- evaluate possible trauma to fetus through
amniocentesis, manipulation, fall, abdominal trauma, etc. (Rh-positive or
Rh-negative mother)
- investigation of anemias
Who should be tested?
Patients with suspected fetal-maternal
hemorrhage
Specimens:
Peripheral Blood in EDTA or heparin
(4°C). Specimens should ideally be
collected within one hour of delivery and sent to the lab ASAP. Testing can be
performed up to 4 days after collection.
Transport: Via Uniship Courier Service
CPT Code: 88184
Test performed: Monday through Saturday
Test reported: Faxed or mailed within 24 hours after
sample is received.
