The random measurement of the transverse diameter of the fetal heart: a potential source of error.

In a recent report it was suggested that the transverse diameter of the fetal heart measured randomly during the cardiac cycle from the real-time image was useful in predicting congenital heart disease (Jeanty P, Romero R, Cantraine F, et al: Fetal cardiac dimensions: a potential tool for the diagnosis of congenital heart disease. J Ultrasound Med 3:359, 1984). Comparing the above approach with M-mode measurements at end-diastole and end-systole suggests that random measurement of the transverse diameter is not appropriate for fetal cardiovascular evaluation because it could predict over 40 per cent of normal fetuses to have an "abnormally" increased cardiac dimension.