Test Code FMB Fetal Maternal Bleed, Flow Cytometry
Useful For
Please see the Flow Cytometry Flow Chart for ordering instructions
Determining the volume of fetal-to-maternal hemorrhage for purposes of recommending an increased dose of Rh immune globulin. May be used to detect a fetomaternal hemorrhage after the occurrence of intrauterine fetal demise.
Patient Preparation
No special patient preparation required
Collection Method
Venous draw
Minimum Volume
2 mL
Container
Purple (EDTA)
Preferred Specimen
Whole Blood
Acceptable Specimens
EDTA Whole Blood
Reference or Target Ranges
0.00-0.14% Fetal RBCs in normal adults
Reportable Units
% Fetal RBCs
Critical Value
Not defined for this assay
Reasons for Rejection
| Hemolysis Threshold | N/A |
| Icterus Threshold | N/A |
| Lipemia Threshold | N/A |
| Other | QNS, contaminated, improperly labled, improper specimen type, specimen clotted |
Specimen Stability
| Ambient | 48 hours |
| Refrigerated (4°C to 8°C) | N/A |
| Frozen(-40°C to 0°C) | N/A |
Performance Information
| Days and Time Performed | Monday – Friday 9AM – 5PM Saturday 8AM – 12PM |
| Expected Turn Around Time | 24 hours |
| Stat Availabilty | No |
| Performing Bench | Flow Cytometry |
| Methodology/Method Description | BD FACSLyric-Flow Cytometry |
Additional Information/Important Notes
Greater than 15 mL of fetal red blood cells (RBC) (30 mL of fetal whole blood) is consistent with significant fetomaternal hemorrhage (FMH). 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 RBCs. 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.
CPT Codes
88184