Systemic to pulmonary shunting masquerading as patent ductus arteriosus: a pitfall in clinical diagnosis.

Patent ductus arteriosus (PDA) frequently complicates the course of respiratory distress syndrome in premature infants. A 920-g, 28 weeks' gestation infant with clinical and radiographic evidence of left to right shunting, was presumed to have a patent ductus arteriosus. Following ductal ligation the signs persisted. Aortic angiogram demonstrated multiple collateral vessels arising from the systemic circulation and communicating with pulmonary vessels. Accurate diagnosis of left to right shunting is imperative if such collateral shunting is not to go undiagnosed.