Whitfield developed an "action line: for managing a pregnancy with rhesus isoimmunization.
(1) week of gestation
(2) delta OD450
The action line is a curve that runs from a delta OD450 of -0.5196 at 24 weeks to 1.4519 at 39 weeks on a semilogarithmic plot of delta OD vs week of gestation.
LOG10(delta OD450) =
= (-0.000197 * ((week of gestation)^3)) + (0.014 * ((week of gestation)^2)) - (0.3457 * (week of gestation)) + 2.450
If the reading for the amniotic fluid is greater than this line and the gestation is < 33.5 weeks, then intrauterine transfusion is performed.
If the reading for the amniotic fluid is greater than this line and the gestation is >= 33.5 weeks, then the fetus is delivered.
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Specialty: Obstetrics & Gynecology, Clinical Laboratory