Delayed clearance of pulmonary fluid in the neonate.

A consecutive series of 647 routine neonatal chest x-ray films taken at a known time within 48 hours of birth was reviewed; 48% had been radiographed within 2 hours. Four hundred and twenty-seven had normal x-ray films, 147 showed evidence of delayed clearance of pulmonary fluid, and other diseases were present in 73. Excessive amounts of pulmonary fluid were not rare in neonates radiographed within 2 hours and were not necessarily associated with symptoms. Low birthweight and prematurity predisposed to delayed clearance of pulmonary fluid; with birthweights greater than 2.3 kg excess of pulmonary fluid was unlikely. Persistence of pleural fluid was more common in the right than the left lung. While radiologically there was no difference in the sex incidence of delayed clearance, symptoms were more common in boys.