Objective: To assess the potential rate of specular reflectors within the fetal heart producing reflections of sufficient amplitude to be mistaken for echogenic intracardiac foci.
Methods: Between July 1999 and December 2000, 200 patients were randomly selected from the University of California, San Francisco, perinatal database who met the following criteria: (1) had singleton pregnancy, (2) delivered at University of California, San Francisco, and (3) had obstetric sonography at University of California, San Francisco, between 18 and 22 weeks' gestation. Bright focal reflections within the heart were judged to be either "true" or "false" echogenic intracardiac foci.
Results: In this population of patients who underwent routine obstetric sonography at a tertiary care hospital, the rate of true echogenic intracardiac focus cases was 11 per 200 (5.5%). The rate of false echogenic intracardiac focus cases was 34 per 200 (17%). The most common locations for identification of a spurious echogenic intracardiac focus were the endocardial cushion, the moderator band, and the tricuspid valve annulus.
Conclusions: A specular reflection from the moderator band was judged the false echogenic intracardiac focus most likely to fool examiners. The rate of specular reflection from the moderator band was 11 per 200 (5.5%). Because it is possible to generate a specular reflection from an interface in the fetal heart in virtually any patient, it is important to exercise caution before diagnosing an echogenic intracardiac focus.