Pneumothoraces secondary to blunt abdominal trauma: aids to plain film radiographic diagnosis and relationship to solid organ injury.

The objective was to identify subtle clues to the diagnosis of small pneumothoraces (PTX) in victims of blunt abdominal trauma (BAT) and to determine the relationship of PTX to solid organ injury. We retrospectively reviewed 1374 abdominal CT scans performed after BAT and assessed each for the presence of PTX and solid organ injury. In patients positive for PTX, the interpretation of the initial portable chest radiograph (PCXR) was noted and the film subsequently reviewed for subtle signs of PTX, presence of subcutaneous emphysema (SQE), and rib fractures. The initial PCXR of 50 consecutive blunt trauma admissions without CT evidence of PTX were reviewed for comparison. Eighty-four patients displayed PTX on CT, of whom 52 had initial PCXR available for review. Eight of 52 (15%) radiographs were initially interpreted as positive for PTX, whereas in our retrospective analysis, an additional 8 were discovered (total 31%). Of these, 23 of 52 (44%) had rib fractures, and 13 of 52 (25%) had SQE. Sixty-four of 1290 patients (5%) without CT findings of PTX sustained solid organ injury, whereas 15 of 84 (18%) with PTX had solid organ injury (significant by chi square analysis, P < 0.001). Although a large number of trauma-related pneumothoraces seen on CT will not be seen on admission PCXR, the search for rib fractures and SQE will enhance the sensitivity of detection. This has prognostic value, as the presence of PTX is related to a significantly increased incidence of abdominal solid organ injury.