Prenatal Diagnosis of Ebstein Anomaly: A Potential Pitfall

Ebstein anomaly is a rare congenital cardiac malformation characterized by varying degrees of downward displacement of the tricuspid valve leaflets into the cavity of the right ventricle. It is an uncommon congenital abnormality with a prevalence of 0.2% to 0.5% of all cardiac malformations. It can appear at any age, from fetal life to adulthood, with a highly variable clinical course. In the fetus and neonate, a targeted echocardiogram has been proven to be reliable in differentiating the variants of Ebstein anomaly. However, because targeted fetal echocardiography cannot be used routinely for all obstetric patients, the ability to recognize Ebstein anomaly from a routine prenatal obstetric sonographic examination is important. The 4-chamber view of the heart, a component of the American Institute of Ultrasound in Medicine guidelines for fetal structural evaluations, is most helpful for the detection of many congenital heart defects, including Ebstein anomaly. The 4-chamber view, however, does have limitations in the diagnosis of certain cardiac malformations. We present a case of prenatal sonography in a fetus with severe Ebstein anomaly that was diagnosed by fetal echocardiography after an initial routine obstetric sonogram showed a normal-appearing 4-chamber view of the heart. However, there were certain sonographic clues on the prenatal sonogram suggesting the diagnosis of Ebstein anomaly.