In an infant with suspected PDA, which of the following would be the optimal method of confirming the diagnosis?

D. Two-dimensional echocardiography with continuous-wave and color-flow Doppler echocardiography.

DISCUSSION: Echocardiography is the best method for confirming the diagnosis of a PDA. Two-dimensional echocardiography can demonstrate PDA and exclude associated anomalies. Doppler echocardiography can demonstrate the shunt, determine direction of shunting, and provide an estimate of shunt magnitude. The chest film is not particularly helpful and may be normal or show cardiomegaly with pulmonary congestion. In general, cardiac catheterization should be reserved for older patients and those with suspected associated anomalies or pulmonary hypertension.