Have Liley charts outlived their usefulness?

Area of Science:

• Maternal-Fetal Medicine
• Neonatal Hematology
• Immunology

Background:

• Rhesus isoimmunization poses a significant risk to fetal well-being.
• Accurate assessment of fetal anemia severity is crucial for timely intervention.
• Current methods for monitoring rhesus isoimmunization require evaluation for improved predictability.

Purpose of the Study:

• To establish normal reference values for amniotic fluid optical density at 450 nm and fetal hemoglobin.
• To assess the correlation between amniotic fluid optical density at 450 nm and fetal anemia severity in rhesus-isoimmunized pregnancies.
• To determine the most reliable method for assessing rhesus isoimmunization severity in the second trimester.

Main Methods:

• Fetoscopic sampling of fetal blood and amniotic fluid from 59 rhesus-isoimmunized pregnancies (18-25 weeks' gestation).
• Measurement of fetal hemoglobin and amniotic fluid optical density at 450 nm.
• Establishment of normal reference values using samples from uncomplicated pregnancies.

Main Results:

• A significant linear correlation was observed between fetal anemia and amniotic fluid optical density at 450 nm.
• Amniotic fluid optical density values were widely scattered, limiting predictive accuracy for anemia severity.
• Trends in optical density did not reliably predict fetal anemia severity in the 25 patients monitored before fetoscopy.

Conclusions:

• Direct measurement of fetal hemoglobin is the only reliable method to determine rhesus isoimmunization severity in the second trimester.
• Amniotic fluid optical density at 450 nm, while correlated, is not sufficiently accurate for predicting fetal anemia severity in this gestational period.
• These findings underscore the importance of direct fetal assessment for managing rhesus isoimmunization.