The reported incidence of PDA varies because of methodological differences related to the population group studied, age of consideration, and method of detection. 16 Although the ductus arteriosus usually is functionally closed within 48 hours of birth, some authorities consider the patent ductus to be abnormal only after 3 months of age. 17 In children who were born at term, the incidence of PDA has been reported to be 1 in 2000 births. 18, 19 This accounts for 5% to 10% of all congenital heart disease. However, if we include children with “silent” patent ductus (those discovered incidentally by echocardiography performed for another purpose), the incidence has been estimated to be as high as 1 in 500. 20 The female to male ratio is 2: 1 in most reports.