Alveolar exudation versus leukocyte aspiration in congenital pneumonia.

Alveolar leukocyte population was studied by means of image analysis techniques in 110 autopsies of infants who died of congenital pneumonia. Considering the short span-life of polymorphonuclear leukocytes and their morphological regressive changes, the working hypothesis established was that an alveolar leukocyte population constituted of immature or young forms would probably correspond to leukocyte exudated in situ rather than emigrated from the chorioamnional blood vessels towards the amniotic fluid and ultimately inspirated into the lung. For the group 0-6 hours of age two completely separated populations of cases were found, 85% of them probably corresponding to true intrauterine pneumonias and the remaining 15% to cases of inspiration of polluted amniotic fluid. In the 6-12 hour period, intermediate cases appeared and a depopulation of the initial clustering of active cases was evident. In the infants who died between 12 and 24 hours a new clustering of active cases appeared suggesting an infection acquired during the process of birth or immediately after.