Which Blunt Trauma Patients Should Be Studied by...

MDCT Bowel & Mesenteric Injury

SE Mirvis, MD: ASER 2005

MDCT of Bowel and Mesenteric Injury: How Findings Influence Management

MDCT of Bowel and Mesenteric Injury: How Findings Influence Management

4th Nordic Trauma Radiology Course 20064th Nordic Trauma Radiology Course 2006

Stuart E. Mirvis, M.D., FACR

Department of Radiology & Maryland Shock-Trauma

University of Maryland School of Medicine

Which Blunt Trauma Patients Should Be Studied by Abdominal CT?

Which Blunt Trauma Patients Should Be Studied by Abdominal CT?

Hemodynamic stability maintainedUnreliable clinical assessmentPositive abdominal exam without overt signs (rebound, rigidity)Positive DPL or sonogram (FAST)Suspect retroperitoneal injuryUnknown source of blood loss



OverviewOverviewBMI < 0.5% admissions to traumaBMI 3-5% of patients having laparotomy for blunt traumaClinical signs present < 50% initiallyDPL variable results for BMI (sensitivity 69%)Sonography - 52% sensitiveNon-operative management of solid organ injuries requires high accuracy for BMI

Role of CT Is ControversialRole of CT Is Controversial

Many literature studies, mainly surgical,cite low sensitivity and high reader dependence (mainly ’80’s, early ’90s)More recent studies using helical and MDCT indicate consistently higher CT accuracy75% of respondents to AAST survey use CT most or all of the time for possible BMIStill actively debated (EAST) 13% perforated SB injuries missed by CT#

#Fakhry SM, Watts DD, Luchette FA. J Trauma 2003;54:295-306



Sharma et al. The role of computed tomography in diagnosis of blunt intestinal and mesenteric trauma (BIMT). J Emerg Med. 2004

Jul;27(1):55-67.

CT of bowel and mesenteric injury

1995 to 2002: 36 cases of BM injury16 isolated and 20 non-isolated injuries Initial CT scan was abnormal in 74% (17 out of 23), and 83% on retrospect (2 additional cases) CT scans were abnormal (initial and repeat) in 96% (22 out of 23). Free fluid (78%), mesenteric stranding or edema (39%), bowel wall hematoma, or edema (30%). Free air 31%, oral contrast extravasation 15%

Allen TL, et al. Computed tomographic scanning without oral contrast solution for blunt bowel and mesenteric injuries in abdominal trauma.

J Trauma. 2004 Feb;56(2):314-22.

Oral vs. no oral contrast

N= 20 patients (500 blunt trauma reviewed)Sensitivity and specificity of CT imaging for the detection of BBMIs were 95.0% and 99.6% CT imaging of the abdomen without oral contrast for detection of BBMIs compares favorably with CT imaging using oral contrast.? Confidence level



MDCT Technique (16-slice)MDCT Technique (16-slice)0.75 or 1.5mm X 16mm slice thicknessPitch 1.25Oral contrast (add rectal for penetrating injury)IV contrast 120-150ml (350 mg/ml)Intravenous contrast @ 6 ml/sec X 15 sec., then 4/sec. X 15 sec. (skull base to pubis)3-5 mm reconstructions for PACSUse 1mm reconstructed images for reference and MPR, 3D, volumetric studies

Diagnostic (operative) CT Signs of Full-thickness Bowel Injury

Bowel contrast extravasationPneumoperitoneum, intramural, intramesenteric air without known or alternative source (20% sensitive)Direct visualization of tear in wall (rare)



CT Pneumoperitoneum

Consider other sources of airLook for free air beneath anterior abdominal wall, adjacent liver, portahepatis, between bowel loopsMore cephalad air in abdomen suggests more cephalad bowel sourceLook in mesentery, bowel wall, portal veinUse bone or lung settings for searchOnly about 20% sensitive

Distinguish fromDistinguish from pneumothoraxpneumothorax



Pneumoperitoneum: windows & levels for bone or lung

Pneumoperitoneum: windows & levels for bone or lung

Jenunal Perforation

Blunt TraumaJenunal Perforation

Blunt Trauma



Was DPL performed?Was DPL performed?Was DPL performed?

Jejunum: Blunt full-thickness injury

Jejunum: Blunt full-thickness injury



Subtle free air: Colon rupture

Subtle free air: Colon rupture

Duodenal ruptureDuodenal ruptureDuodenal rupture



Direct rupture of duodenum; free air

& hematoma

Direct rupture of duodenum; free air

& hematoma

Colon rupture: Intramural air, free air

Colon rupture: Intramural Colon rupture: Intramural air, free airair, free air



Intramural duodenal air delayed duodenal

hematoma – 4d

Intramural duodenal air delayed duodenal

hematoma – 4d

Oral contrast leakOral contrast leak

Requires oral contrastSpills into low resistance peritoneal spaceActive bleeding usually dissects into mesentery and has surrounding hematomaExtravasated urine from intraperitoneal bladder rupture can confuse diagnosis (delayed imaging)



Oral contrast spillage:

OR jejunal perforationOral contrast spillage:

OR jejunal perforation

Fecal spillage right colon &

Lumbar Hernia



Indirect Signs of Bowel Injury: Indirect Signs of Bowel Injury:

Bowel wall thickening (subjective)Adjacent mesenteric infiltration or hematoma Dilated, fluid-filled loops - atonicIncreased wall contrast enhancementFree fluid of ? source

Bowel Wall Thickening

Normal bowel 1-2 mm partially distended; 3-4 mm when collapsed Seen in proximal small bowel most commonly5-6 mm mild thickening, 7-8mm moderate, >8 mm markedContusion localized thickening involving adjacent loops (prox. jejunum)No other findings equals contusionBowel wall hematoma can co-exist



Bowel contusion & free fluid:

Full-thickness bowel injury

Bowel contusion & free fluid:

Full-thickness bowel injury



Bowel Contusion

Jejunal perforation at OR



Horse kicks broom into abdomen !

Duodenal transection –direct diagnosis

Delayed colonic hematoma;

Pt. on anticoagulants

Delayed colonic hematoma;

Pt. on anticoagulants



Bowel Wall EnhancementBowel Wall Enhancement

Patchy increased density in bowel with thickened wallOften seen with mesenteric edemaMechanism: slowed perfusion, leaky capillaries, re-perfusion phenomenonMandates careful follow-up

Thick-walled enhancing bowel

Thick-walled enhancing bowel



Enhancing small bowel wall

Enhancing small bowel wall

Intraperitoneal FluidIntraperitoneal Fluid

Always measure fluid densityTrace amount occasionally seen in cul-de-sac of women of child-bearing yearsMay be the only sign of injury to bowel/mesentery or solid organ (20%+)Larger amounts of fluid in more locations increases chance of injuryMesenteric triangles (bowel – mesenteric origin likely)



Pelvic Fluid: MalePelvic Fluid: MalePelvic Fluid: Male

CT of Mesenteric InjuryCT of Mesenteric Injury

Active bleedingHematoma Infiltration (misty, hazy)Triangle sign of intramesenteric fluidFascial thickeningDifficult to distinguish operative from non-operative lesions



Mild mesenteric contusion (misty- hazy)

Mild mesenteric contusion Mild mesenteric contusion (misty(misty-- hazy)hazy)

Mesenteric hematoma:

renal infarctMesenteric Mesenteric hematomahematoma::

renal infarctrenal infarct



Colonic contusion with mesenteric tear -hematomaColonic contusion with mesenteric tear -hematoma

Active mesenteric bleed-delayed diffusion

Active mesenteric bleed-delayed diffusion



Active mesenteric bleed: Sentinel clotActive mesenteric

bleed: Sentinel clot

Mesenteric hematoma: Sentinel clot

Mesenteric hematoma: Sentinel clot



Active Mesenteric Bleed

Delayed

Active bleeding mesenteric hematoma;

Tear at root of mesentery

Active bleeding mesenteric hematoma;

Tear at root of mesentery



Active mesenteric bleed

Enveloping Mesenteric Hematoma

Enveloping Mesenteric Hematoma



Intramural gastric hematoma

Management for Indirect CT Findings

Serial physical examination* F/U CT 6-8 hoursFollow-up sonography (same examiner)Diagnostic peritoneal lavage (WBC, bile)Exploration



MVC: Abdominal Pain- initial CT

Follow-up CT – 10 hr.

Jejunal rupture in OR



Mimics & Masks of Bowel InjuryMimics & Masks of Bowel Injury

Shock bowel: follows prolonged hypotension or cardiac arrests

Diffuse bowel wall thickeningPatchy increased enhancementDilated, fluid-filled bowelSmall bowel mainly involvedMesenteric edema commonUsually flat IVC, renal veinsMay see increased renal and adrenal enhancement, decreased spleen density



Shock BowelShock Bowel




Shock Bowel: Small bowel & colonShock Bowel: Small bowel & colonShock Bowel: Small bowel & colon

Shock bowelShock bowelShock bowel




Mimics & Masks of Bowel InjuryMimics & Masks of Bowel Injury

Increased venous return pressureOver resuscitation, cardiac tamponade, tension pneumothorax, hematoma compressing IVCDistended IVC and renal veinsDiffuse edematous small bowel and mesenteryOften retroperitoneal, pericholecysticedema and peritoneal fluidRarely involves colon



Pericardial

TamponadePericardial

Tamponade

Increased CVP

Periportallymphedema

Increased CVP

Periportallymphedema



Increased CVP

Small bowel edema

Increased CVP

Small bowel edema

Summary

• What are the CT findings of bowel and mesenteric injury?

• Which of those findings indicates need for surgical intervention? observation? anxiety?

• What are the major concurrent trauma findings that mimic or mask signs of bowel and mesenteric injury?



Thank You

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