Mesenteric and Small Bowel Trauma

Published on 19/07/2015 by admin

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Last modified 22/04/2025

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 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

TOP DIFFERENTIAL DIAGNOSES

• “Shock bowel”
• Coagulopathy (intramural hematoma)
• Vasculitis

PATHOLOGY

 

CLINICAL ISSUES

• 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

DIAGNOSTIC CHECKLIST

• 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)
image
(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.

image
(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.
image
(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.

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

TERMINOLOGY

Definitions

• Injury to mesentery &/or small intestine

IMAGING

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

DIFFERENTIAL DIAGNOSIS

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

Coagulopathy

• 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)

Vasculitis

• CT findings

image Segmental bowel wall thickening with mucosal hyperenhancement, submucosal edema
image Pneumatosis ± portal venous gas

– May result from ischemia or medical therapy (e.g., steroids)

PATHOLOGY

General Features

• Etiology

image Most common causes

– Motor vehicle accidents (MVA) > falls, assault
image Impact injuries

– Crushing of bowel against spine
– Location: SB of limited mobility (duodenum, near ligament of Treitz, ileocecal valve)
– Transverse tears of mesentery → hematoma → bowel infarction
image Rapid deceleration injuries

– Abrupt forward movement of proximal jejunum from its fixation by ligament of Treitz
– Shearing force between restricted and mobile bowel: Transsection at duodenojejunal flexure
image Gastric injury

– More common in children than adults
– Increased risk: Distended stomach after eating
– Associated injuries: Splenic rupture, left thorax injury
image Duodenal injury

– Hematoma, ectopic air, or contrast (perforation)
– Location: Descending 2nd and horizontal 3rd
– 3rd portion crushed against spine by direct blow
– Associated injuries: Pancreatic head, left lobe of liver

image Intra- &/or retroperitoneal
image Jejunal and ileal injury

– Hematoma, bowel wall discontinuity, thickening
– At or near ligament of Treitz and ileocecal valve
– Symptoms and signs develop slowly (secondary to neutral pH, relative absence of bacteria)
image Colon injury

– Compression of upper abdomen (steering wheel, seat belts)
– Location: Transverse colon, sigmoid colon, cecum
– Transverse: Intramural hematoma or serosal tear
– Ascending or descending: Mesenteric avulsion, full thickness laceration, transection, ischemia
– Complications: Ischemic stricture, perforation
image Mesenteric injury

– Hematoma: Most common “alimentary” injury seen on CT
– Complications: Disruption of mesenteric vasculature, hemorrhage, GI tract perforation
– Active mesenteric bleeding requires surgery

image Embolization of bleeding vessels may cause bowel ischemia
image Injury to adjacent bowel cannot be excluded

Gross Pathologic & Surgical Features

• Contusion, laceration, bowel discontinuity
• Wall thickening, blood clot, rupture
• “Degloving” injury: Serosa is torn from surface of bowel

image Often results in delayed ischemic injury to bowel
image Ischemic stricture or perforation are recognized complications

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Abdominal pain, distension, tenderness, guarding
image Hypotension, tachycardia
image Loss of consciousness, shock due to increased blood loss
• Clinical profile

image History of MVA, abdominal pain, distension, tenderness, and guarding
• Lab data

image Altered CBC, electrolytes, BUN, creatinine, amylase, PT, PTT, and hematocrit
• Diagnostic peritoneal lavage (DPL)

image RBC > 150,000/mm³, WBC > 500/mm³
image Food, bile, or bacteria on Gram stain from aspirate
image “Positive” DPL often resulted in nontherapeutic laparotomy (minor visceral or mesenteric injuries were found commonly

– Rarely used in most trauma centers

Demographics

• Age

image Any age group
• Gender

image M = F
• Epidemiology

image Abdominal trauma: Leading cause of death in USA in patients < 40 years of age
image Children: Intramural hematoma is more common than transection

– Children are injured with less kinetic energy
image Adults: Bowel wall transection is more common than intramural hematoma
image Bowel and mesenteric injuries are found in 2- 5% of patients taken to surgery after abdominal trauma

Natural History & Prognosis

• Complications

image Perforation → sepsis → abdominal abscess → peritonitis → shock → death
• Prognosis

image Good if diagnosed and treated early
image Poor if diagnosis and treatment delayed beyond 24 hours

– Increases morbidity and mortality up to 65%
• Use of seat belt restraints has decreased mortality from motor vehicle crash

image Incidence of bowel and mesenteric injuries has increased
image Lap portion of seat belt can act as a fulcrum and cause direct trauma to bowel and mesentery
image Clinicians and radiologists should look for seat belt contusion of the lower abdominal wall

– Seat belt sign is highly predictive of bowel and mesenteric injury

Treatment

• Minor injury: IV fluids, monitor vital signs, blood transfusion, antibiotics

image Mortality of 5-30% with isolated small bowel injury
• Major injury: Surgery for perforation or active bleed

image Injured bowel is usually resected with immediate reanastomosis
image Anastomosis may be postponed in cases of abdominal contamination

Associated Injuries

• Traumatic abdominal wall hernia

image Most common is avulsion of muscle insertions on iliac crest
image Highly associated with bowel and mesenteric injury
• Injury to solid abdominal viscera

image Present in most, but not all, cases of traumatic bowel injuries

DIAGNOSTIC CHECKLIST

Consider

• CT is much more accurate in diagnosis of bowel injury from blunt trauma as opposed to penetrating trauma (e.g., stab wound to abdomen)
• Bowel and mesenteric injuries are missed by clinicians and radiologists much more often than injuries to solid viscera

Image Interpretation Pearls

• CT evidence of extraluminal air/contrast, bowel wall thickening, free fluids, mesenteric “stranding”

image
(Left) Axial CECT in a 19-year-old man presenting with abdominal pain after an MVC shows free air image, hyperdense thickened bowel wall image, and infiltrated mesentery consistent with a hematoma image. Jejunal perforation was revealed at surgery.
image
(Right) Axial CECT in a 71-year-old woman with severe abdominal pain after an MVC shows extraluminal gas image adjacent to the thickened and collapsed cecum image. Note adjacent bowel wall thickening image of the terminal ileum. Cecal and distal ileal perforations were confirmed at surgery.
image
(Left) Axial CECT in a 58-year-old man with abdominal pain after an MVC shows active arterial extravasation image and a sentinel clot from a mesenteric laceration. A torn mesenteric artery was revealed at surgery, but no bowel injury.

image
(Right) Axial CECT in a 22-year-old man injured in a bicycle accident shows a mesenteric hematoma (34 HU) image within an interloop compartment. Note the angular margins of the mesenteric collection. There were no signs of bowel injury and the patient recovered without surgery.
image
(Left) Axial CECT in a 62-year-old woman presenting with abdominal pain after an MVC demonstrates an abdominal wall hematoma from a seat belt injury image. Seat belt contusions are highly associated with bowel and mesenteric injuries.

image
(Right) Axial CECT in the same patient illustrates active arterial bleeding image within a mesenteric hematoma. The adjacent bowel was also found to be injured at surgery. Active mesenteric bleeding from trauma generally demands surgical intervention.

image
(Left) This 44-year-old man was injured in an MVC. CT shows blood image (45-50 HU) in the upper abdomen without an apparent hepatic or splenic injury.
image
(Right) Another CT section in the same patient shows higher density (65 HU) blood (sentinel clot) as angular (polygonal) mesenteric image and left paracolic image collections. Mesenteric laceration without bowel injury was confirmed at surgery.
image
(Left) This 30-year-old woman was injured in an MVC. CT shows a thick-walled jejunum image and active bleeding image into the mesentery, with fluid isodense to enhanced blood vessels.

image
(Right) CT in the same patient, shown at lung windows, shows free intraperitoneal gas (air) image, diagnostic of transmural laceration. The active mesenteric bleeding alone would have warranted surgical intervention in this case.
image
(Left) This 54-year-old woman was injured in an MVC. CT shows active hemorrhage image, hyperenhancing, thickened SB wall image, and interloop hematoma image. Also seen is an abdominal wall hematoma from the seat belt impact image and diffuse mesenteric infiltration image.

image
(Right) CT in the same patient shows a traumatic abdominal wall hernia containing segments of colon and small bowel. Extraluminal gas is noted image. At surgery, serosal avulsion and transmural laceration of the small bowel were confirmed.

image
(Left) This young man was injured in an MVC. CT with lung windows shows free intraperitoneal air image.
image
(Right) The same CT section at soft tissue windows shows free peritoneal fluid image measuring about 20 HU, likely representing a mixture of blood and extraluminal bowel contents.
image
(Left) CT in the same patient shows higher density (60HU) sentinel clots image adjacent to jejunum and cecum, and more free air image.

image
(Right) Another CT section in the same patient shows intermediate density fluid (35HU) in the pelvis image. No solid visceral injuries were evident.
image
(Left) An additional CT section in the same patient shows infiltration and hematomas image in the subcutaneous fat of the abdominal wall at the level of the iliac crests. This is a classic seat belt sign.

image
(Right) A sagittal reformatted CT section in the same patient shows a horizontal fracture image through the L3 vertebral body and posterior elements, a classic Chance fracture. This and the seat belt contusion are highly associated with bowel and mesenteric injuries. Jejunal and cecal lacerations were confirmed at surgery.
image
Axial CECT shows sentinel clot and active bleeding image in mesentery and blood in the left paracolic gutter image.

image
Axial CECT shows mesenteric hematoma and active bleeding image. Also note the “triangular” and interloop collections of blood image, another sign of bowel or mesenteric injury.
image
Axial CECT shows large omental/mesenteric hematoma and active bleeding image.
image
Axial CECT shows large omental/mesenteric hematoma with active bleeding image.
image
Axial CECT shows small bowel perforation following a seat belt injury from a motor vehicle accident. Note the extravasated oral contrast in the left paracolic gutter image associated with a mesenteric hematoma image.
image
Axial CECT at a more cranial plane of section in the same patient demonstrates abdominal wall contusion image from a seat belt injury and pneumoperitoneum image.
image
Axial CECT shows active arterial extravasation into the mesentery of the right colon following blunt trauma. Note the high-attenuation focus of arterial bleeding image surrounded by a large hematoma image.
image
Axial CECT in the same patient shows diffusion of extravasated contrast into the mesentery image. At surgery, a right hemicolectomy was required to stop bleeding.
image
Axial CECT shows bowel perforation. Note the hyperdense small bowel from a reperfusion injury image, water density in the left paracolic gutter image, and an intraloop compartment image.
image
Axial CECT shows a bowel perforation with massive pneumoperitoneum image. Note the hyperdense small bowel with visualization of the vasa recta in the thickened bowel wall image from a reperfusion injury.
image
Axial CECT shows a jejunal hematoma treated nonoperatively following blunt trauma. Note the marked thickening of the proximal jejunum image with adjacent mesenteric hematoma image.
image
Axial CECT shows cecal perforation. Note the mural thickening and focal interruption of the cecal wall image. Adjacent ectopic gas is present image, confirming perforation.
image
Axial CECT shows free air and blood in the perihepatic location. Note the distal small bowel and sigmoid transections.
image
Axial CECT shows fluid (blood and bowel contents) in the paracolic gutter and mesentery, along with free air image in this transected small bowel.
image
Axial CECT shows free air image from jejunal transection.
image
Axial CECT shows seat belt contusion image, mesenteric infiltration, bowel wall thickening, and free air image in this jejunal transection.
image
Axial CECT shows fluid in the anterior pararenal space in this duodenal laceration.
image
Axial CECT shows a thick-walled jejunum and mesenteric blood. Surgery confirmed jejunal transection, splenic, and renal lacerations.
image
Axial CECT shows a thick-walled distal small bowel, mesenteric blood image, and 2 sites of active mesenteric bleeding image.
image
Axial CECT shows intramural hematoma of jejunum.

SELECTED REFERENCES

1. Barnett, RE, et al. Small bowel trauma: current approach to diagnosis and management. Am Surg. 2014; 80(12):1183–1191.

2. Honaker, D, et al. Blunt traumatic abdominal wall hernias: Associated injuries and optimal timing and method of repair. J Trauma Acute Care Surg. 2014; 77(5):701–704.

3. Steenburg, SD, et al. Multi-detector CT of blunt mesenteric injuries: usefulness of imaging findings for predicting surgically significant bowel injuries. Abdom Imaging. 2014. [ePub].

4. Ekeh, AP, et al. Diagnosis of blunt intestinal and mesenteric injury in the era of multidetector CT technology—are results better? J Trauma. 2008; 65(2):354–359.

5. Linsenmaier, U, et al. Diagnosis and classification of pancreatic and duodenal injuries in emergency radiology. Radiographics. 2008; 28(6):1591–1602.

6. Hanks, PW, et al. Blunt injury to mesentery and small bowel: CT evaluation. Radiol Clin North Am. 2003; 41(6):1171–1182.

7. Hawkins, AE, et al. Evaluation of bowel and mesenteric injury: role of multidetector CT. Abdom Imaging. 2003; 28(4):505–514.

8. Butela, ST, et al. Performance of CT in detection of bowel injury. AJR Am J Roentgenol. 2001; 176(1):129–135.

9. Brody, JM, et al. CT of blunt trauma bowel and mesenteric injury: typical findings and pitfalls in diagnosis. Radiographics. 2000; 20(6):1525–1536. [discussion 1536-7].

 

Federle, MP. Diagnosis of intestinal injuries by computed tomography and the use of oral contrast medium. Ann Emerg Med. 1998; 31(6):769–771.

Levine, CD, et al. CT findings of bowel and mesenteric injury. J Comput Assist Tomogr. 1997; 21(6):974–979.

Nghiem, HV, et al. CT of blunt trauma to the bowel and mesentery. AJR Am J Roentgenol. 1993; 160(1):53–58.

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