Bowel and mesenteric trauma

Last revised by Adrià Roset Altadill on 17 Aug 2024

Bowel and mesenteric trauma can result from blunt force, penetrating and iatrogenic trauma. CT is the gold standard imaging modality but CT findings are nonspecific 12.

The bowel and mesentery are injured in ~2.5% (range 0.3-5%) of blunt force abdominal trauma 1,3,5,8. However not surprisingly, bowel and mesenteric injuries are more frequent after penetrating trauma 8. Bowel injury has consistently been found to be the most common traumatic abdominopelvic injury missed on CT 11.

Gunshot wounds (~75%) and stabbings (~20%) are the leading causes of bowel and mesenteric injury from penetrating trauma 8. Motor vehicle collisions are the most common cause of blunt trauma followed by falls, assaults and sports-related trauma 4,6.

From most to least common sites of bowel injury 1,4,6:

The mechanism of bowel injury include crush/compression type, shearing type (from fixed point of mesentery) and burst type (from increased intra-luminal pressure) and can include 4:

  • perforation

  • mural hematoma or edema

  • active hemorrhage

  • serosal tear

  • degloving (very rare)

Mesenteric injuries can include:

Several grading schemes (RAPTOR and BIPS) using a variety of clincial parameters and CT findings hve been validated and correlate with operative findings and the need for surgical intervention.

The erect chest x-ray may show free subdiaphragmatic gas due to traumatic bowel injury but radiographs indicated in the setting of trauma are almost always performed as a supine projection which reduces the sensitivity of pneumoperitoneum. Abdominal radiography is not indicated in trauma when CT is readily available.

  • definitive signs:

    • visible bowel wall discontinuity 7

    • perforation

      • in blunt trauma, the presence of extra-luminal oral contrast media (if used) or bowel contents; extra-luminal free gas (especially in the absence of pneumothorax/pneumomediastinum) 2

      • in penetrating trauma, extra-luminal free gas is not specific to bowel perforation; extra-luminal contrast media/bowel contents leak and a wound track extending to bowel is considered the most sensitive; wall thickening/mesenteric contusion is less sensitive 2

  • suggestive signs 7

    • mural hematoma: discontinuity in the bowel wall with mural thickening (>3-4 mm); may be complete (i.e. perforated) or incomplete 2,4

    • moderate/large volume of free fluid without solid organ injury 2-3

    • intermesenteric (interloop) fluid, often forming triangles

    • abnormal bowel wall enhancement: decreased due to mesenteric vascular interruption and small bowel ischemia, or increased due to vascular permeability secondary to hypoperfusion 7

    • positive seatbelt sign increases the likelihood of traumatic bowel injuries 9

    • feacalisation 12

  • definitive signs:

    • active extravasation of contrast media is indicative of active bleeding and a significant mesenteric injury 3

    • intermesenteric (interloop) free fluid, often forming triangles 7

    • beading and termination of mesenteric vessels 4, 7

    • abrupt termination of the mesenteric vessels 7

    • accumulation ('pooling') of contrast on multiphase imaging

  • suggestive signs 7

    • mesenteric infilatration: haziness and fat stranding

    • mesenteric hematoma

    • bowel wall thickening

Even with increasing non-operative management of traumatic abdominal organs (e.g. liver or spleen laceration), traumatic bowel and mesenteric injuries such as perforation or active mesenteric bleeding still require operative management 3.

  • shock bowel: diffuse bowel wall thickening (from edema) that is hyperenhancing

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