Bowel and mesenteric trauma

Bowel and mesenteric trauma can result from blunt force, penetrating and iatrogenic trauma.

Epidemiology

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

Pathology

Etiology

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

Types

From most to least common sites of bowel injury :

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 :

  • perforation
  • mural hematoma or edema
  • active hemorrhage
  • serosal tear
  • degloving (very rare)

Mesenteric injuries can include:

  • active bleeding from a laceration
  • mesenteric hematoma

Radiographic features

CT
Bowel injury
  • definitive signs:
    • visible bowel wall discontinuity
    • 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)
      • 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
  • suggestive signs
    • mural hematoma: discontinuity in the bowel wall with mural thickening (>3-4 mm); may be complete (i.e. perforated) or incomplete
    • moderate/large volume of free fluid without solid organ injury
    • intermesenteric fluid 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
    • positive seatbelt sign increases the likelihood of traumatic bowel injuries
Mesenteric injury
  • definitive signs:
    • active extravasation of contrast media is indicative of active bleeding and a significant mesenteric injury
    • intermesenteric free fluid, often forming triangles
    • beading and termination of mesenteric vessels
    • abrupt termination of the mesenteric vessels
    • accumulation ('pooling') of contrast on multiphase imaging
  • suggestive signs
    • mesenteric infilatration: haziness and fat stranding
    • mesenteric hematoma
    • bowel wall thickening

Treatment and prognosis

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 .

Differential diagnosis

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