Causes of congenital unilateral pulmonary hypoplasia: a study of 33 cases.

A review of the roentgenograms and clinical records of 33 children with primary congenital underdevelopment of one lung showed that 9 patients had simple pulmonary hypoplasia, 8 had anomalous venous return to the right atrium or the inferior vena cava (scimitar syndrome), 7 had an absence of the ipsilateral pulmonary artery, 7 had an accessory diaphragm, and 2 had a pulmonary sequestration adjacent to a small diaphragmatic hernia.