Lab

Modified Apt Test

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Modified Apt Test, Apt Test

  • See Also
  1. Late Pregnancy Bleeding
  2. Vasa Previa
  3. Neonatal Black Stool
  • Indications
  1. Vasa Previa
    1. Late Pregnancy Bleeding evaluation
  2. Infant with black stools thought due to swallowed maternal blood
    1. See Neonatal Black Stool
  • Mechanism
  1. Differentiates Fetal from Maternal Blood
  2. Fetal Hemoglobin contains 2 alpha subunits and 2 gamma subunits (contrast with beta subunits in adults)
    1. Fetal blood is resistant to denaturation when alkali is applied (fetal blood remains pink)
    2. Adult blood denatures in contact with alkali and turns brown
  • Technique
  1. Collect bloody fluid
  2. Add a small amount of tap water (Hemolyzes blood)
  3. Centrifuge sampleppp
  4. Add 5 cc pink supernatant to 1 cc Sodium Hydroxide 1%
  5. Read in 2 minutes (may be difficult)
    1. Pink sample indicates fetal Hemoglobin
    2. Yellow-Brown sample indicates adult Hemoglobin