Accurate prediction of fetal hemoglobin by Doppler ultrasonography.
OBJECTIVE
To assess the feasibility of using the middle cerebral artery peak systolic velocity (MCA-PSV) to predict the actual value of fetal hemoglobin in fetuses undergoing a first cordocentesis for detection of anemia caused by maternal red cell alloimmunization.


METHODS
Doppler velocimetry of the MCA-PSV was performed in 18 fetuses before an initial cordocentesis. Hemoglobin and MCA-PSV values were expressed as multiples of the median to adjust for the changes that both parameters demonstrate with gestational age. In each fetus we determined: 1) the expected (using a cubic mathematical function describing the correlation between fetal hemoglobin and MCA-PSV) and the observed (determined at the time of the cordocentesis) hemoglobin value; and 2) the percentage differences between the expected and the observed hemoglobin values.


RESULTS
Gestational age at the time of the Doppler study ranged from 19 to 31 weeks. On 15 occasions, the fetuses demonstrated anemia. A quadratic relationship was found between the hemoglobin multiples of the median and the percentage differences between the expected and the observed hemoglobin values. As the values of hemoglobin decreased, the percentage difference between expected and observed values significantly decreased (R(2) = 0.48, P <.05). The cubic model estimated fetal hemoglobin well in severely anemic fetuses and less well when the fetus was not anemic.


CONCLUSIONS
Doppler measurement of the MCA-PSV appears to be a valuable tool for estimating hemoglobin concentration in fetuses at risk for anemia. The correlation between hemoglobin and MCA-PSV becomes more accurate as the severity of anemia increases.
Mari
Giancarlo
G
Department of Obstetrics and Gynecology, Prenatal Diagnosis and Fetal Therapy Center, University of Virginia Health Science Center, Charlottesville, Virginia, USA. gm6p@virginia.edu
Detti
Laura
L
Oz
Utku
U
Zimmerman
Roland
R
Duerig
Peter
P
Stefos
Theodor
T
D000328:Adult; D000740:Anemia / Q000000981:diagnostic imaging*; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D005319:Fetal Hemoglobin / Q000032:analysis*; D005865:Gestational Age; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal
D005319:Fetal Hemoglobin