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HelpTest Code FMB Fetomaternal Bleed, Flow Cytometry, Blood
Reporting Name
Fetomaternal Bleed,Flow Cytometry,BUseful For
Determining the volume of fetal-to-maternal hemorrhage for the purposes of recommending an increased dose of the Rh immune globulin
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole Blood EDTAOrdering Guidance
This test is for the detection of fetal bleed, it should not be used to detect the hereditary persistence of fetal hemoglobin (HPFH) or to detect fetal maternal hemorrhage in a mother with HPFH. For HPFH diagnosis, order HBEL1 / Hemoglobin Electrophoresis Evaluation, Blood.
NY State Clients: Testing is available; order FMBNY / Fetomaternal Bleed, New York, Blood.
Shipping Instructions
Specimen must arrive within 5 days (preferably 24-72 hours) of collection.
Specimen Required
Container/Tube: Lavender top (EDTA)
Specimen Volume: 6 mL
Collection Instructions:
1. Fill evacuated tube as completely as possible.
2. Do not centrifuge.
3. Invert several times to mix blood.
4. Send whole blood specimen in original tube. Do not aliquot as aliquoting into or out of a sample tube can adversely affect test results.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood EDTA | Refrigerated (preferred) | 5 days | |
| Ambient | 5 days |
Reference Values
≤3.75 mL of fetal red blood cells in normal adults
Day(s) Performed
Monday through Sunday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
88184-Flow cytometry, cell surface, cytoplasmic
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| FMB | Fetomaternal Bleed,Flow Cytometry,B | 75308-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 28204 | Mother's Rh | 10331-7 |
| 28202 | Fetal-Maternal Bleed | 55730-6 |
| 28203 | Rh Immune Globulin | 55731-4 |
| 4058 | Remarks | 48767-8 |
Interpretation
Greater than 15 mL of fetal red blood cells (RBC) (30 mL of fetal whole blood) is consistent with significant fetomaternal hemorrhage (FMH).
A recommended dose of Rh immune globulin (RhIG) will be reported for all specimens. One 300 mcg dose of RhIG protects against a FMH of 30 mL of D-positive fetal whole blood or 15 mL of D-positive fetal RBC. Recommended standard of practice is to administer RhIG within 72 hours of the fetomaternal bleed for optimal protective effects. The effectiveness of RhIG decreases beyond 72 hours post exposure but may still be clinically warranted. This assay has been validated out to 5 days post collection.
Clinical Reference
1. Roback J, Combs MR, Grossman B, Hillyer C, eds. In: Technical manual. 16th ed. AABB Press; 2008:625-637, 888
2. Iyer R, McElhinney B, Heasley N, Williams M, Morris K. False positive Kleihauer tests and unnecessary administration of anti-D immunoglobulin. Clin Lab Haematol. 2003;25(6):405-408
3. Cohn CS, Delaney M, Johnson ST, Katz LM, eds. Technical Manual. 20th ed. AABB Press; 2020
Report Available
Same day/1 dayMethod Name
Flow Cytometry