Abdominal CT: bowel and mesenteric trauma

Evaluating bowel and mesenteric trauma

Diagnosing bowel injuries

Remember that with solid organ injuries, you can easily see haematomas and linear lacerations throughout the enhancing tissue.

In contrast, bowel injuries can be very subtle and sometimes are only suspected because of unexplained blood products in the abdomen. You should be concerned about blood when you see fluid measuring greater than 30 Hounsfield units (HU).

In the example below, the density is 55 HU.

Many bowel injuries don’t go completely through the intestinal wall, such as a tear of the outer serosal lining or a hematoma causing wall thickening.

Timely diagnosis

Acute traumatic injury to the bowel and mesentery is less common than solid organ injury. However, detection of even a subtle bowel injury is essential. This is because a delayed diagnosis and repair of bowel injury can result in serious morbidity, such as perforation, abscess, and complicated surgery with impaired healing.

Remember that even severe solid organ injuries are often managed nonoperatively when possible. In contrast, a questionable or subtle bowel injury usually requires prompt surgical exploration and repair.

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Diagnosing mesenteric injuries

There can also be injuries to the mesentery that result in bleeding from the mesenteric vessels. These injuries carry a risk of bowel ischemia as they disrupt the blood flow to and from the bowel. Injury to the mesentery can occur on its own or it can be associated with bowel injury.

On computed tomography (CT) imaging, mesenteric injury will look like stranding and dense fluid in the mesentery as a result of blood products. There can also be active venous or arterial bleeding.

These injuries are important to report and may still require surgical attention as they can threaten the blood supply of the bowel.

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Example Case

In the case below, there was a relatively large amount of pelvic blood surrounding bowel loops, but no definite site of injury. A hidden bowel injury seems possible in this case.

This patient was taken to surgery and a mesenteric and serosal injury of the cecum was identified and repaired.

A delay in detecting this diagnosis could have resulted in perforation, abscess, and a more complicated surgery with longer recovery. Thus, the presence of unexplained blood on trauma CT was enough to raise the suspicion of a bowel injury.

Team approach

Note that it’s important to take a team approach to reporting and understanding subtle findings that might indicate an underlying injury. Imaging findings are correlated with the clinical picture from the trauma team. Additionally, short-term follow-up imaging can help to determine if a patient can be safely observed or requires surgical exploration.

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References

• Top 100 CT scan quiz. LITFL

Radiology Library: Abdominal Trauma. Solid organ injury

• Hartung MP. Abdominal Trauma: bowel and mesenteric trauma
• Hartung MP. Bowel trauma [case studies]
• Hartung MP. Mesenteric injury and bowel shock [case studies]
• Hartung MP. Diaphragmatic injuries

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