The "dependent viscera" sign in CT diagnosis of blunt traumatic diaphragmatic rupture

OBJECTIVE. The objective of our study was to describe the "dependent viscer a" sign and determine its usefulness at CT in the diagnosis of diaphragmati c rupture after blunt abdominal trauma. MATERIALS AND METHODS. The study sample consisted of 28 consecutive patient s (19 men, nine women) between 17 and 74 years old (mean age, 31 years) who had undergone abdominal CT and subsequent emergency laparotomy after a blu nt trauma. Ten patients had a diaphragmatic rupture (six, right-sided; four , left-sided) at laparotomy. An experienced radiologist unaware of the surg ical findings retrospectively reviewed the CT scans, and then a second radi ologist reviewed the scans to provide interobserver agreement. Note was mad e of discontinuity of the diaphragm, intrathoracic herniation of abdominal contents, and waistlike constriction of bowel (the collar sign). Also noted was whether the upper one third of the liver abutted the posterior right r ibs or whether the bowel or stomach lay in contact with the posterior left ribs. Either of these findings was termed the "dependent viscera" sign. The radiologists' detection rate of diaphragmatic rupture on the CT scans via observance of the dependent viscera sign was determined. Interobserver agre ement was assessed using Cohen's kappa statistic. RESULTS. The dependent viscera sign was observed on the CT scans of 100% of the patients with a left-sided diaphragmatic rupture and of 83% of the pat ients with right-sided diaphragmatic rupture. Both observers missed one cas e of right-sided diaphragmatic rupture. The radiologists' overall rate of d etecting diaphragmatic rupture was 90% using the dependent viscera sign. We found excellent interobserver agreement (kappa = 1) for detection of the d ependent viscera sign and for the diagnosis of diaphragmatic tear on CT sca ns. CONCLUSION. The dependent viscera sign increases the detection at CT of acu te diaphragmatic rupture after blunt trauma.