Test used to differentiate between maternal and fetal blood in a given sample:(AIIMS May 2013, May 2012)
Correct Answer: Apt test
Description: Ans. c. Apt test (Ref: Dutta 7/e p234, 651; Williams 23/e p617-618)Both Apt test and Kleihauer-Betke test can be used to detect the presence of fetal blood within a sample but test used to differentiate between maternal and fetal blood in a given sample is Apt test.Apt Test:Used to detect the presence or absence of fetal blood (qualitative) in a vaginal discharge to rule out vasa previa late in pregnancy or to detect the origin of a neonatal bloody vomiting, whether it is a genuine upper GI hemorrhage/ hemoptysis or simply swallowed maternal blood during delivery or from cracked nipple.Kleihauer-Betke Test:The sample is maternal peripheral smear and is used to see how much of fetal blood (quantitative) has been transfused into the maternal serum in order to assess the risk of isoimmunization and then the risk of hemolytic disease of newborn.Both of them relies on the fact that HbF is resistant to alkali (Apt) and acids (Kleihatier-Betke) and so the HbA containing RBCs (Maternal) will be hemolyzed but not the fetal RBCs as they contain the HbF.When fetal blood needs to be differentiated from maternal bloodApt test is usedQ (Qualitative estimation)When the amount of fetal bleeding needs to be estimatedKleihauer-Betke test is usedQ (Quantitative estimation) Apt testKleihauer-Betke testSource of sampleMaternal or neonatalQMaternalQPrincipleAdding 1% NaOH destroys adult HbA but not fetal HbFAdding acid destroys adult HbA but not fetal HbF Assessment TypeQualitativeQQuantitativeQResultPositive means blood is of fetal originQReported in estimated milliliters of fetal bloodQ
Category:
Gynaecology & Obstetrics
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