Laboratory Lab results are too important to go anywhere else.

Fetal RBC Assay

Fetal RBC Assay (FMH), Fetal hemoglobin, Hemoglobin F, Fetal RBC, Flow Cytometry, Fetal RBC

Test Codes

EPIC: LAB6413

Department

Flow Cytometry

Specimen Collection Criteria

Collect: One Lavender or Pink-top EDTA tube.

Physician Office/Draw Specimen Preparation

Specimens must be refrigerated (2-8°C or 36-46°F) if testing is not performed within 4 hours of collection.

Preparation for Courier Transport

Transport: Whole blood, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

Clotted specimens.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): 5 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Flow Cytometry Laboratory (Monday – Friday, 7:30 am – 3:00 pm, Saturday 7:30 am – 1:30 pm).
Royal Oak Hematology Laboratory (Saturday after 1:30 pm, Sunday, and Holidays).

When the Flow Cytometry Laboratory is not available, "URGENT" requests from Emergency Center will be processed by the Hematology Laboratory as an "Acid Elution test." Inpatient "URGENT" requests must be evaluated by resident on call for appropriateness. ("Urgent" is defined as a fetal-maternal bleed that jeopardizes the baby.) 

Performed

Monday – Friday (7:30 am – 3:00 pm) and Saturday (7:30 am – 1:30 pm) in Royal Oak Flow Cytometry, Saturday after 1:30 pm, Sunday, and Holidays, in Royal Oak Hematology (Acid Elution).

Reference Range

Normal: Less than or equal to 0.1% Hemoglobin F positive red blood cells.

Test Methodology

Immunophenotyping by Multiparameter Flow Cytometry.

Interpretation

Greater than 0.1% is indicative of Fetal Maternal hemorrhage.

Clinical Utility

• Quantitation of erythrocytes containing fetal hemoglobin (HgbF) is used to determine the extent of a fetal-maternal hemorrhage. This is important in estimating the dosage of RhIg for RhD negative mothers, but also in evaluating complicated pregnancies or those involving trauma and explaining fetal or newborn distress.
• This method offers a rapid and reliable alternative to the laborious Kleihauer-Betke (acid elution) for fetal-maternal hemorrhage assessment, as well as affording a method for "F-cell" quantitation which is useful in assessing the efficacy of some hematological therapies for hemoglobinopathies.

CPT Codes

85460

Contacts

Last Updated

8/9/2023