The prenatal diagnosis of congenital heart disease--a practical approach for the fetal sonographer.

With the widespread use of diagnostic ultrasound to evaluate the human fetus, it is now possible to diagnose a number of anomalies of varying organ systems. Although most anomalies of the central nervous, gastrointestinal, genitourinary, and skeletal systems are recognizable at birth, serious ones involving the cardiovascular system are often silent until the neonate demonstrates signs of cardiovascular compromise. Because an ever increasing number of fetuses are routinely scanned during pregnancy, it becomes imperative to incorporate a simple, logical approach to screen for cardiovascular disease during each fetal examination. The approach outlined in this paper would suggest that one method is the routine examination of the four-chamber view. Although there are a number of fetal and maternal risk factors which predispose to congenital heart disease, we have diagnosed a number of anomalies simply on the basis of the "screening" four-chamber examination in the "low-risk" fetus. For this reason, an attempt to examine the four-chamber view of the fetal heart should be done during each routine fetal examination. If an abnormality is noted, then a Level II, or consultative echocardiographic examination should be carried out. If a fetus at risk for congenital heart disease is being examined, a complete examination of the cardiovascular system (Levels I and II) should be performed. If the above approaches are integrated into obstetrical scanning, in the not too distant future it will be commonplace to diagnose cardiovascular anomalies prior to birth and thus provide the best care during the transition from the intrauterine to the extrauterine environment for the potentially cardiovascularly compromised neonate. The experience gained in our laboratory during the past 5 years strongly suggests that what is "today's research will become tomorrow's clinical tool."