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 :
- jejunum (near ligament of Treitz/D-J flexure)
- ileum (near ileocecal valve)
- colon (cecum, transverse colon, sigmoid colon)
- rectum
- duodenum (D2 and D3 segments)
- stomach (greater curvature)
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