Mesenteric and Small Bowel Trauma

 Polygonal fluid collections between folds of mesentery, bowel loops

image Indicates bowel &/or mesenteric injury

• Active bleeding = isodense with enhanced vessels

• Extraluminal gas: Intra- or retroperitoneal air
image May be absent even with transmural lacerations

• Seat belt sign: Infiltration or hematoma in subcutaneous fat of lower anterior abdominal wall

• Free fluid without an apparent solid organ injury
image Larger amounts, especially of blood attenuation (> 35 HU) are due to trauma

image Look carefully for mesenteric, bowel, or solid visceral injury


• “Shock bowel”

• Coagulopathy (intramural hematoma)

• Vasculitis



• Bowel and mesenteric injuries are found in 2-5% of patients taken to surgery after abdominal trauma

• Active mesenteric bleeding requires surgery

• Use of seat belt restraints has decreased mortality from motor vehicle crash
image Incidence of bowel and mesenteric injuries has increased


• Check for mechanism of injury

• Don’t succumb to satisfaction of search

• Solid visceral injuries are often more obvious, but less important than injuries to bowel or mesentery

• CT is much more accurate in diagnosis of bowel injury from blunt trauma as opposed to penetrating trauma (e.g., stab wound to the abdomen)

(Left) Axial CECT in a 24-year-old man injured in a motor vehicle crash (MVC) shows a sentinel clot image, adjacent to thick-walled jejunum, and active bleeding, as evidenced by the contrast extravasation image. All characteristic findings in intestinal trauma.

(Right) Coronal CECT in the same patient shows an injured branch of the superior mesenteric artery with a large focus of contrast extravasation image. The mesenteric injury was surgically repaired and a segment of small intestine was resected.

(Left) Axial CECT in a 28-year-old man who was injured in an MVC demonstrates ectopic gas image adjacent to a thick-walled jejunal segment image, indicative of transmural laceration or perforation.

(Right) Axial CECT in the same patient demonstrates mesenteric stranding image, a characteristic finding in the setting of intestinal trauma.



• Injury to mesentery &/or small intestine


General Features

• Best diagnostic clue
image Bowel wall thickening, mesenteric infiltration, intraperitoneal blood, ± extravasation of enteric or vascular contrast medium

• Location
image Duodenum and proximal jejunum are most common sites

Radiographic Findings

• Radiography
image Flank stripe sign: Increased density zone separates vertical colon segments from properitoneal fat and peritoneal reflection

image Dog’s ear sign: Pelvic fluid collections displace bowel from urinary bladder

Fluoroscopic Findings

• Water-soluble contrast study
image Fold thickening, luminal narrowing, extravasation

image Mainly for duodenal hematoma or laceration

CT Findings

• Must view at abdominal and lung windows

• Bowel wall thickening > 3 mm (sensitivity of 75%)

• Bowel wall enhancement hyperdense to psoas muscle or isodense to blood vessels
image Wall enhancement + thickening + free fluid strongly suggests perforation

• Mesenteric infiltration (“stranding”)
image Small hemorrhages: Streaky soft tissue infiltration of mesenteric fat

image Sentinel clot sign: Localized > 60 HU mesenteric hematoma at site of bleeding

• Intra-/retroperitoneal free fluid: Hemoperitoneum or bowel contents
image Hemoperitoneum: Present is essentially all bowel or mesenteric injuries

image Polygonal fluid collections between folds of mesentery, bowel loops
– Indicates bowel &/or mesenteric injury

– Does not result from injury to solid viscera

image Hematoma (> 60 HU), liquefied blood (35-50 HU)

image Bowel content, extravasated enteric contrast (10-30 HU)

image Active bleeding = isodense with enhanced vessels

image Bowel rupture at sites of oral contrast extravasation

• Extraluminal air: Intra- or retroperitoneal air
image Not diagnostic of bowel perforation (also seen in barotrauma and mechanical ventilation)
– Often seen in subphrenic spaces

– Between mesenteric leaves, omental interstices

– May be absent even with transmural lacerations

• Intramural air and extraluminal air and interloop free fluid
image Indicates full thickness tear

• Bowel discontinuity: Diagnostic of transmural laceration, but rare finding

• Extraluminal oral contrast material: Rare, but specific for perforation

• Seat belt sign: infiltration or hematoma in subcutaneous fat of lower anterior abdominal wall
image Highly predictive of injury to bowel and mesentery

• Chance fracture: Transverse plane fracture through vertebral body and posterior elements
image Highly associated with bowel and mesenteric injuries

• Free fluid without apparent solid organ injury
image Normal in young woman (physiological)

image Small amounts in pelvis of near-water attenuation in men may be due to overhydration

image Larger amounts, especially of blood attenuation (> 35 HU), are due to trauma
– Look carefully for mesenteric, bowel, or solid visceral injury

– Alert clinical team of need for close and repeated monitoring if surgery is to be delayed

Ultrasonographic Findings

• Grayscale ultrasound
image Free fluid in abdomen and pelvis

image Focused abdominal sonography for trauma (FAST exam)
– Never shows bowel injury; only nonspecific free intraperitoneal fluid

Angiographic Findings

• Conventional
image Vascular transection, laceration, pseudoaneurysm, arteriovenous fistula

Imaging Recommendations

• Best imaging tool
image Multiplanar CECT

• Protocol advice
image IV contrast bolus at 3 mL/sec

image Oral contrast use is safe, but uncommonly indicated


Shock Bowel

• Intense mucosal enhancement, submucosal edema (not blood)

• With diffuse mesenteric edema, signs of hypovolemia 
image Collapsed IVC, hyperenhancement of kidneys ± adrenals, etc.

• Reversible sign of recent hypotension

• Resolves quickly with fluid resuscitation


• May result in intramural hematoma of bowel

• Usually due to anticoagulant treatment

• Spontaneous etiologies: Idiopathic thrombocytopenic purpura, leukemia, hemophilia

• Barium studies, CT of SB
image Segmental, extensive, or localized changes

image Uniform, regular thickening of valvulae conniventes with symmetric, spike-like configuration, decreased luminal diameter simulating “stack of coins”

image Intramural hematoma: Intramural mass (∼ 60 HU)

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Mesenteric and Small Bowel Trauma

Full access? Get Clinical Tree

Get Clinical Tree app for offline access