Sonographic markers of hemoglobin Bart disease at midpregnancy.
OBJECTIVE
To evaluate the efficacy of various sonographic markers at midpregnancy in predicting fetal hemoglobin Bart disease.


METHODS
Four hundred eighty-eight pregnancies at risk of having fetuses with hemoglobin Bart disease were recruited for prenatal diagnosis with cordocentesis at 18 to 21 gestational weeks. Before cordocentesis, the sonographic markers, including cardiothoracic ratio, placental thickness, pericardial effusion, pleural effusion, ascites, subcutaneous edema, cord edema, dilated umbilical vein, and amniotic fluid index, were assessed and recorded. The definite fetal diagnosis was based on blood analysis. The efficacy of each sonographic marker in predicting hemoglobin Bart disease was evaluated by sensitivity and specificity.


RESULTS
Among 488 pregnancies undergoing prenatal diagnosis, 100 fetuses were proved to be affected by hemoglobin Bart disease. The cardiothoracic ratio gave the highest sensitivity, 95.0%, with specificity of 96.1%, followed by placental thickness. Signs of hydrops fetalis were observed in 33.0% of cases; they did not increase the sensitivity of the cardiothoracic ratio but strongly reinforced the diagnosis when they appeared.


CONCLUSIONS
At midpregnancy, sonographic markers can effectively differentiate normal pregnancies from those with fetal hemoglobin Bart disease. Among couples at risk with no sonographic markers, the risk of having an affected child is nearly eliminated. The most sensitive marker was the cardiothoracic ratio, followed by placental thickness.
Tongsong
Theera
T
Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. ttongson@mail.med.cmu.ac.th
Wanapirak
Chanane
C
Sirichotiyakul
Supatra
S
Chanprapaph
Pharuhas
P
D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D005318:Fetal Heart / Q000000981:diagnostic imaging; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D012680:Sensitivity and Specificity; D013909:Thorax / Q000000981:diagnostic imaging* / Q000196:embryology*; D016216:Ultrasonography, Prenatal; D017085:alpha-Thalassemia / Q000000981:diagnostic imaging*