Delta OD450 (ΔOD450) is a spectrophotometric measurement performed on **amniotic fluid** obtained via amniocentesis in pregnancies at risk for severe Hemolytic Disease of the Fetus and Newborn (HDFN), typically due to Rh incompatibility. It measures the **bilirubin pigment** level in the amniotic fluid. Bilirubin is a breakdown product of hemoglobin from fetal red cell hemolysis. The ΔOD450 value represents the deviation in optical density at 450 nm wavelength (where bilirubin absorbs light) from a baseline expected for gestational age. An **elevated ΔOD450** indicates increased bilirubin in the amniotic fluid, which correlates with the **severity of fetal hemolysis and anemia**. The results are plotted on the **Liley graph** (or Queenan chart for earlier gestation) to determine the zone of severity (Zone I: mild/no disease, Zone II: moderate, Zone III: severe). This guides management decisions, such as the need for intrauterine transfusion (IUT) or early delivery.

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Zambia

• Joseph Soko – 101 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies