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Test ID: Kleihauer-Betke
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Kleihauer-Betke
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Useful For
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Determining the volume of fetal-to-maternal hemorrhage for the purposes of calculation of the adjusted dose of the Rh immune globulin.
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Method name and description
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Cytochemical test using a commercial Fetal Hemoglobin Kit, Kleihauer test or Acid elution test, is a blood test used to measure the amount of fetal hemoglobin transferred from a fetus to a mother's bloodstream. It is usually performed on Rh-negative mothers to determine the required dose of Rh(D) immune globulin (RhIg) to inhibit formation of Rh antibodies in the mother and prevent Rh disease in future Rh-positive fetuses.
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Clinical information
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Rh immune globulin (RhIG, anti-D antibody) is given to Rh-negative mothers who are pregnant with a Rh-positive fetus. Anti-D antibody binds to fetal D-positive red cells, preventing stimulation of the maternal immune response and formation of anti Rh antibodies that will eventually attack the fetal red cells causing hemolysis. RhIg can be given either before or after delivery. The volume of FMH determines the dose of RhIg to be administered.
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Specimen type / Specimen volume / Specimen container
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Whole blood.
Container/Tube: EDTA tube (may be part of the CBC)
Specimen Volume: 3 ml.
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Collection instructions / Special Precautions / Timing of collection
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Collect maternal blood in EDTA. Collect as soon as possible after delivery or prior to birth if a fetal bleed is suspected.
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Relevant clinical information to be provided
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History of maternal hemoglobinopathies such as Hereditary Persistence of Fetal Hemoglobin (HPFH) or other maternal hemoglobinopathies that result in elevated HbF such as thalassemias or sickle cell disease.
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Storage and transport instructions
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Ambient / Refrigerated (2-8 °C)
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Specimen Rejection Criteria
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1-Specimens collected after Rh immunoglobulin administered.
2-Cord or Fetal blood.
3-Clotted/Hemolyzed specimens.
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Biological reference intervals and clinical decision values
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Fetal cell percentage %: < 0.05
Reference: Sure-tech diagnostic, Associates, Inc., St. Louis, MO. Fetal Hemoglobin. Procedure no. 101. Revised 1991.
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Factors affecting test performance and result interpretation
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In case of maternal Hereditar Persistence of Fetal Hemoglobin (HPFH) or other maternal hemoglobinopathies that result in elevated HbF (thalassemias, sickle cell hemoglobin), the KB test will be falsely positive
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Turnaround time / Days and times test performed / Specimen retention time
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72 hours
Test is performed daily
Specimen is retained for 3 days at 2-8ºC
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