MDCT of blunt abdominal trauma: The correlation of extraluminal air, fluid, and unexplained fluid with bowel perforation

To correlate blunt bowel perforation with CT findings of extraluminal air, extraluminal fluid, and unexplained extraluminal fluid and determine their diagnostic values. During a study period of 30 months, the CT findings of 394 patients with abdominal trauma were prospectively recorded. A retrospective chart review of these patients for bowel injuries, choice of treatments, and final outcome was performed. The correlation of bowel perforation with CT findings of extraluminal air, extraluminal fluid, and unexplained extraluminal fluid was computed. The diagnostic values and likelihood ratios of these CT findings were determined. Among 394 CT scans, 22 had extraluminal air, 259 had extraluminal fluid, 82 had unexplained extraluminal fluid. Blunt bowel perforation occurred in 24 (6.1%) patients and was significantly correlated with extraluminal air (68.2% vs. 2.4%, p<0.001), extraluminal fluid (8.9% vs. 0.7%, p=0.001), as well as unexplained extraluminal fluid (23.2% vs. 2.3%, p<0.001). The likelihood ratio of positive extraluminal air, extraluminal fluid, and unexplained extraluminal fluid for bowel perforation was 32.9, 1.5, and 3.1 respectively. Extraluminal air had the highest specificity (98.1%) but low sensitivity (62.5%), extraluminal fluid had the highest sensitivity (95.8%) but low specificity (36.2%). By comparison, unexplained fluid in the absence of solid organ injury had a higher specificity than unspecified extraluminal fluid (73.3% vs. 36.2%). The presence of extraluminal air or fluid on trauma CT is significantly correlated with blunt bowel perforation. Extraluminal air is specific and warrants immediate surgical attention, whereas unexplained fluid should initiate aggressive work-up such as diagnostic peritoneal lavage for clarifying bowel perforation.