Acute rupture of the diaphragm due to blunt trauma: Diagnostic sensitivity and specificity of CT

OBJECTIVE. The purpose of this study was to determine the diagnostic sensitivity and specificity of CT in detecting acute rupture of the diaphragm after blunt trauma. MATERIALS AND METHODS. Abdominal CT scans taken before surgery of 11 patients with diaphragmatic rupture (eight left and three right) and 21 patients with intact diaphragms after major acute blunt abdominal trauma were independently reviewed by three observers who were unaware of surgical findings. Retrospective note was made of diaphragmatic discontinuity, intrathoracic herniation of abdominal contents, waistlike constriction of bowel ('collar sign'), and associated findings. Right and left hemidiaphragms were graded as intact or ruptured, and these findings were correlated with surgical findings. Individual and average observer sensitivity and specificity in detecting acute diaphragmatic rupture were calculated. RESULTS. Of the 11 cases of diaphragmatic rupture, diaphragmatic discontinuity was seen in eight, visceral herniation was seen in six, and the 'collar sign' was seen in four cases. Hemoperitoneum or hemothorax completely obscured visualization of the ruptured diaphragm in three cases. Individual diagnostic sensitivity for detecting diaphragmatic rupture was 54-73%, and specificity was 86-99%. Average sensitivity for the three observers was 61% (95% confidence interval, 41-81%), and average specificity was 87% (95% confidence interval, 76-99%). CONCLUSION. CT is highly specific in diagnosing acute diaphragmatic rupture and detects approximately two thirds of acute diaphragmatic ruptures after blunt trauma.