Blunt Traumatic Colon Perforation

Axial non contrast CT image of the abdomen shows a localized collection of air and high-density fluid (C) medial to the ascending colon (AC) and the site of colonic wall discontinuity (between arrows). Note skin and subcutaneous swelling/contusion of the right flank. 

Sagittal-reformatted CT image shows similar findings as  on the axial imaging. The entire length of the ascending colon (AC) is better appreciated and the collection (C) is located posteromedial to the colon within the retroperitoneal space. Colonic perforation was confirmed at surgery. 

Facts:

• Uncommon injury in blunt trauma
• Severe direct force is usually required to produce this injury, mostly from motor vehicle collision
• Often associated with other injuries, both intra- (liver, spleen, small bowel mesentery) and extra-abdominal (skeletal, facial, neurologic)
• CT may not be 100% sensitive. Findings could be overlooked in multiply-injured patients, large patients or if metallic monitoring/support devices are obscuring the area.
• "Normal" CT could be misleading when other factors such as physical examination is not taken into account. Re-review of images to look for subtle free fluid/air is essential in these cases.

CT Findings:

• Discontinuity of bowel wall
• Extraluminal contrast leakage
• Extraluminal air either intra- or retroperitoneal (nonspecific, can be seen after DPL, mechanical ventilation, barotrauma, etc)
• Intramural air
• Bowel wall thickening
• Bowel wall enhancement
• Mesenteric fat stranding
• Intraperitoneal and retroperitoneal fluid

References:

1. Barden BE et al. Perforation of the colon after blunt trauma. South Med J 2000;93(1)
2. Brody JM, et al. CT of blunt trauma bowel and mesenteric injury: typical findings and pitfalls in diagnosis. RadioGraphics 2000;20: 1525