(7) Prepare a total hemoglobin control by adding 0 05 ml of Drabkin's
reagent to 5.0 ml of distilled water. Mix as above.
(8) Measure the absorbances of the fetal and total hemoglobin solutions
against the appropriate blanks.
Absorbance fetal hemoglobin solution
X 10 = Percent fetal hemoglobin
Absorbance total hemoglobin solution
Report percent to nearest tenth (0.1).
e. Sources of Error.
(1) If the hemoglobin concentration of the hemolysate is less than 5 g per
the sensitivity of the procedure is decreased.
(2) Poor pipetting technique causes a significant error due to the small
(3) If the absorbance of the fetal hemoglobin solution is greater than 0.700,
dilute 1.0 ml of the fetal hemoglobin solution with 9.0 ml distilled water. Read the
absorbance against the total hemoglobin blank. Multiply the calculated result by 10.
(1) The alkali denaturation test can be performed on bloody rectal
discharges from infants. This test is used to determine whether the discharge is due to
ingested maternal blood or a gastrointestinal lesion. The procedure is as follows:
(a) Add a small amount of bloody discharge to 10 ml of distilled water.
(b) Add 0.2 ml 10 percent sodium hydroxide solution.
(c) If the solution turns pink, it is fetal blood. A muddy brown solution
indicates blood of maternal origin.
(2) Fetal hemoglobin constitutes approximately 80 percent of a newborn
infant's hemoglobin. This decreases to approximately 5 percent at 6 months.