Occult pneumothorax in patients with abdominal trauma: CT studies.

Abdominal CT, which routinely includes the lower thorax, is an important adjunct to supine chest radiography in detecting chest injury in patients with blunt abdominal trauma. In 1,086 consecutive patients with blunt abdominal trauma, 223 of whom had both supine chest radiography and abdominal CT, 49 patients examined with both techniques had pneumothoraces, 28 of them occult (seen only on CT). To help guide management, we established three categories of occult pneumothorax, based on size and location: (a) minuscule ( 1 cm in greatest thickness, but not extending beyond the midcoronal anterior; (c) anterolateral (extending beyond the midcoronal line)