Diagnostic Performance of Doppler Ultrasonography for the Detection of Fetal Anemia

This study evaluates the diagnostic performance of Doppler ultrasound in diagnosing fetal anemia. Data were taken from relevant study reports published in peer-reviewed journals identified after a literature search in electronic databases. Random effects meta-analyses were performed by pooling the effect sizes of diagnostic indices (sensitivity, specificity, positive/negative predictive values, and false-positive rate) or correlation coefficients reported by individual studies. As a result, 31 studies (1848 pregnancies; gestation age, 28.25 weeks [95% confidence interval {CI}, 26.87-29.63]) were included in the meta-analysis. Anemia was found in 63.7% (95% CI, 49.7-77.7) fetuses, and severe anemia was found in 36.7% (95% CI, 26.9-46.4) fetuses. Sensitivity and specificity of Doppler ultrasound for detecting fetal anemia in alloimmunized fetuses at middle cerebral artery peak systolic velocity cutoff of 1.5 multiple of median for gestation age were 83.42% (95% CI, 71.75-95.09) and 80.30% (95% CI, 73.58-87.02), respectively. Positive predictive value, negative predictive value, and false-positive rate were 76.35% (95% CI, 65.98-86.72), 80.0% (95% CI, 76.63-83.37), and 10.4% (95% CI, 5.9-14.9), respectively. Correlation coefficient between hematological anemia and Doppler ultrasound-measured blood flow velocity was -0.706 (95% CI, -0.765 to -0.635; P < 0.00001). In conclusion, Doppler ultrasound-measured middle cerebral artery peak systolic velocity at 1.5 multiple of median provides good diagnostic strength for the detection of alloimmunized fetal anemia. A strong correlation between Doppler velocimetric measures and hematological anemia is also observed.