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KLEIHAUER-BETKE
MessageHematology
Test Code
LAB762
Alias/See Also
Fetal RBC, Fetal Maternal Hemoglobin Screen, Circulating Fetal RBC, KHB
CPT Codes
85460
Preferred Specimen
2 ml whole blood (lavender top tube, EDTA) from the mother
Minimum Volume
1 mL whole blood
Other Acceptable Specimens
Pink top tube, EDTA
Instructions
May be ordered separately or as a reflex from Blood Bank FMH Rapid Screen test if positive.
Specimen Stability
Ambient 24 hours
Refrigerated 3 days
Refrigerated 3 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Cord blood is fetal blood and is not suitable for assessing fetal/maternal hemorrhage.
Methodology
Fetal hemoglobin (Hemoglobin F) can be distinguished from adult hemoglobin by its resistance to acid elution. When blood smears are immersed in acid buffer, adult hemoglobin is eluted from the erythrocytes, whereas fetal hemoglobin is not. If blood smears are treated with an acid buffer and subsequently stained, erythrocytes having hemoglobin F will take up the stain, while those containing only adult hemoglobin appear as "ghosts".
Report Available
Same 24 hour period
Limitations
Reticulocytes may resist elution and can appear as Hb F-containing cells.
Hematological disorders in adults may produce increased levels of fetal-type cells.
Hemoglobin S will stain like HbF
Hematological disorders in adults may produce increased levels of fetal-type cells.
Hemoglobin S will stain like HbF
Reference Range
0.0-0.3% Fetal RBC
Clinical Significance
Fetal hemoglobin estimations are sometimes made to determine possible hemorrhage in the newborn, particularly in cases where there are signs of rectal bleeding. Assays of Hemoglobin F are also applied to adults as an aid in diagnosing certain types of anemia. For example, from 10 - 90% fetal hemoglobin is encountered in patients with thalassemia major. Moreover, a small increase of fetal blood is usually observed in patients with sickle cell disease.
It is becoming increasingly common in cases of Rh incompatibility to suppress immune reactions to red blood cells entering maternal circulation from the fetus. The amount of specific gamma globulin, containing anti Rh[D] to be administered, is calculated by assessing the magnitude of fetal-maternal hemorrhage.
It is becoming increasingly common in cases of Rh incompatibility to suppress immune reactions to red blood cells entering maternal circulation from the fetus. The amount of specific gamma globulin, containing anti Rh[D] to be administered, is calculated by assessing the magnitude of fetal-maternal hemorrhage.
Performing Laboratory
HHN / HHI Lab
