Lab

Kleihauer-Betke

search

Kleihauer-Betke

  • Indications
  1. Measures fetal cells in maternal circulation
  2. Used in assessing for Rh Sensitization
    1. Maternal blood Rh negative
    2. Large antepartum bleed
  • Mechanism
  1. Blood Film stained with acid elution
  2. Fetal Hgb more acid resistant
  3. Fetal RBC darkly stained, Maternal RBC "ghosts"
  • Technique
  1. Count Fetal cells per 50 low power fields
  2. Five cells per 50 (lpf) = 0.5 ml bleed
  • Interpretation
  1. Calculate Maternal Blood Volume (ml) =
    1. (Pre-pregnant weight in kg) x 70 ml/kg x
    2. (1.0 + (0.5 x weeks gestation/36)) -
    3. Estimated Blood loss (ml) at time of test
  2. Calculate Fetal Whole Blood (ml) =
    1. (Fetal Cell Count/Maternal Cell Count) x
    2. Maternal Blood Volume
  3. Rh Immune Globulin (RhoGAM) Dose
    1. Give 300 ug per 30 ml fetal whole blood or 15 ml pRBC