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 f luid, 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 f luid, 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 f luid, 82 had unexplained extraluminal f luid. Blunt bowel perforat ion 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 f luid, and unexplained extraluminal f luid 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 f luid on trauma CT is significantly correlated with blunt bowel perforation. Extraluminal air is specific and warrants immediate surgical attention, whereas unexplained f luid should init iate aggressive work-up such as diagnostic peritoneal lavage for clarifying bowel perforation.