Only 20-35% of major congenital cardiac anomalies are detected by routine ultrasound screening. It is often suggested that patients at risk should therefore undergo a fetal echocardiogram. We examined the accuracy of fetal echocardiogram when compared to standard fetal ultrasound in detecting cardiac anomalies, stratified by maternal BMI.
Retrospective chart review. Neonates with discharge diagnosis of any congenital cardiac anomaly between 2003 and 2008 were included. Maternal charts were reviewed for gestational age at ultrasound, ultrasound diagnosis, echocardiogram diagnosis, and maternal BMI. Subjects were classified into BMI categories by CDC criteria: underweight and normal (control): 18.5-24.9 kg/m2, overweight: 25.0-29.9 kg/m2, and obese: 30 kg/m2 and above. Detection rates between the two modalities were calculated and compared. Accuracy of the ultrasound and echocardiogram diagnoses defined as true positive rate plus the true negative rate were compared and stratified by maternal weight categories.
86 neonates with congenital heart disease were included. 48 of these neonates had fetal echocardiograms. Accuracy of detection of fetal heart defects was higher with echocardiograms when compared to standard fetal ultrasounds (73% vs. 48%). As maternal BMI increased, the accuracy of fetal echocardiography decreased slightly, but standard ultrasound decreased rapidly. The odds ratio for diagnosis of congenital heart disease was 2.8 for fetal echocardiogram compared with standard ultrasound (p=0.01). When compared to ultrasound, fetal echocardiograms were more likely to detect a cardiac anomaly in women with increasing BMI (p=0.07).
In patients where a fetal echocardiogram is indicated, it often provides more comprehensive results than the standard ultrasound. This suggests that obese patients may be good candidates for a routine fetal echocardiography referral. However, further work is needed to determine if fetal echocardiograms would work as well when used as a routine screening test in this population.
© 2009 Mosby, Inc. Published by Elsevier Inc. All rights reserved.