Pleural effusions and pulmonary hypoplasia

Nine cases of fetuses with pleural effusions are presented in which the diagnosis was made by ultrasound before the thirtieth week of gestation. A ratio of lung span to hemithorax diameter was calculated and ranged from 0.44 to 0.77 (mean 0.60). At autopsy, pulmonary hypoplasia was confirmed in all cases by criteria based on the ratio of lung weight to total body weight. Because pleural effusions occurring in the midtrimester can be detected and may lead to pulmonary hypoplasia, consideration should be given to definitive in utero therapy when no other major fetal abnormality is detected. (Am J Obstet Gynecol 1987; 157:1252-5.)