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Blunt Abdominal Trauma
• Motor vehicle collision (MVC, ~75%),
motorcycle crashes (MCC), pedestrian-
automobile impacts, falls and assaults
• Multiple different organ injuries
• Major complications: peritonitis,
hemorrhagic shock and death
• Two categories:
– Solid organ injuries
– Hollow organ injuries
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Blunt abdominal trauma evaluation
Hemodynamically stable Hemodynamically unstable
FAST
CT
FAST/DPL
Positive Negative
Laparotomy
Positive Negative
Positive Negative
Search for other sources
of hemorrhage
Consider discharge
Minor injury
Observation
Major, nonoperative
ICU observation
Operative
Laparotomy
Observation
Repeated FAST
CT
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Penetrating Abdominal Trauma
• Foreign object pierces skin. Gunshot wounds (GSW),
stab wounds
• External appearance of penetrating wound does NOT
determine extent of internal injuries
• Define trajectory of penetrating wound and consider all
possible internal injuries
• Complications: hemorrhagic shock
• Organs injured: penetrating > blunt trauma = SB, colon/
rectum, stomach, pancreas, diaphragm
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Penetrating abdominal trauma evaluation
Hemodynamically stable Hemodynamically unstable
Laparotomy FAST
Positive Negative
Stab Wound GSW
To Back/flank – CT indicated
Anterior – CT considered
Thoracoabdominal – CT considered
Shotgun to back/flank – CT indicated
Shotgun to anterior – Laparoscopy/otomy
Bullet (higher velocity) – Laparotomy
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Focused Assessment with
Sonography for Trauma (FAST)
• Been used for over 30 years
• Bedside screening to aid clinicians in identifying
free fluid in thorax or abdomen
• Initially designed to focus primarily on detection
of free fluid – now modified to detect
pneumothorax, quantification of fluid
• Sensitivity 80-90%, specificity 95-100% for free
fluid
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Anatomical Considerations
• Site of fluid accumulation depends on
position of patient and source of bleeding
• Free fluid in dependent compartments
– RUQ Morison’s pouch right paracolic gutter
pelvis
– LUQ subphrenic space splenorenal recess
left paracolic gutter pelvis
– Pelvis = rectovesical pouch (M), pouch of Douglas (F)
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FAST
PERICARDIUM
• Global cardiac
function
• Chamber size
• Normal pericardium =
white line surrounding
heart
• Sweeps anterior-
posterior
PERIHEPATIC
• Right pleural effusion,
free fluid in Morison’s
pouch, free fluid in
paracolic gutter
• Mid-axillary line
between 8th-11th ribs
with oblique scanning
plane
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FAST
PERISPLENIC
• Left pleural effusion, free
fluid in subphrenic space
and splenorenal recess,
free fluid in left paracolic
gutter
• Left diaphragm, spleen,
left kidney
PELVIC
• Longitudinal and
transverse views
• Free fluid in anterior
pelvis or cul-de-sac
• Ideally should be done
before Foley
• Differentiate partially filled
bladder with free fluid by
– Emptying bladder (Foley)
or
– Retrograde bladder filling
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Hemopericardium
• Anechoic stripe surrounding the heart within parietal
and visceral layers of bright hyperechoic pericardial sac
• Especially helpful in penetrating trauma
• Classic clinical signs found in < 40% of cases with
proven cardiac tamponade
• Bedside cardiac US
– Reduces time of diagnosis and disposition to OR
– Increases survival
• Sensitivity 100%, specificity 96.9%, accuracy
97.3%
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Free Pleural Fluid
• Anechoic stripe above diaphragm
• US is at least comparable to CXR
• Minimum fluid needed
– Upright CXR 50-100 mL
– US 20 mL
• Differentiation of fluid from pleural thickening and
lung contusion
• Complement CXR in diagnosis of hemothorax in
supine patient
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US Features of Organ Injuries
• Not specific goal of FAST to detect organ injury
• Acute laceration
– Fragmented areas of increased or decreased echo
• Contained intraparenchymal or subcapsular
hemorrhages
– Isoechoic or slightly hyperechoic (difficult to detect)
• Low sensitivity esp splenic injury
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Pitfalls of FAST
• Contraindication (when emergent Sx
needed)
• Overreliance on FAST: esp negative ones
• Limitations of FAST:
– Morbidly obese
– Massive subcutaneous emphysema
• Pregnancy
• Technical difficulties
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Detection of Pneumothorax
• Pneumothorax occult on CXR in 29-72%
• Extended FAST (EFAST) can identify
pneumothorax before CXR
• Best resolution of pleural interface with high-
resolution probe and small footprint but most
practical using same probe as FAST
• Identify contiguity of visceral and parietal pleura
using simple US signs
– Normal = lung sliding (B), seashore sign (M mode)
– Abnormal = loss of lung sliding (B), stratosphere (M),
lung point (B & M)
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Detection of Pneumothorax
• Normal lung sliding
– Twinkling at level of pleural
line in real time
– Sliding of visceral against
parietal pleura
– Seashore sign on M mode
– Avoid using filters that reduce
noise
Bright pleural line that moves on realtime scanning
seashore
Seashore sign on M mode
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Pneumothorax:
Loss of Lung Sliding
• Sensitivity 80-100%
(lower in trauma)
• Specificity 83-100%
• Real-time US
• M mode = Barcode or
stratosphere sign
• “Lung point” most specific
sign (alternating areas of
barcode and seashore
signs)
Barcode or stratosphere sign
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Pitfalls of US on Pneumothorax
• “Loss of lung sliding” alone is not specific
for pneumothorax
– Pleural adhesion/thickening
– Atelectasis
– Lobec/pneumonectomy
– One-lung intubation
• Look for “Lung Point” for specificity
• Comparison with contralateral lung
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FAST vs. CT
FAST CT
Aim for Detection of hemoperitoneum Detection of
hemoperitoneum, organ
injuries
Accuracy (for
hemoperitoneum)
88% Nearly 100%
Accuracy (for
organ injuries)
74% Nearly 100%
Missed rate 15% of hemoperitoneum. Up to
25% of liver/spleen, most renal/
pancreas/bowel
Benefits Fast, bedside, no patient prep
needed, no risk of IV contrast
issues
More accurate, guide
non-operative
management
ACR*
Recommendation
Done first and only if
hemodynamic unstable before
going to OR
Done if hemodynamic
stable
*The American College of Radiology
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When to do CT
• Blunt abdominal trauma
– Stable patients with positive FAST
– Stable patients with negative FAST but
suspicious for injuries (by clinical or labs)
• Penetrating abdominal trauma
– Stable patients with injury to back & flank
– (stable patients with thoracoabdominal &
anterior stab wounds)
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At Time of Receiving
Consultation
• Must know mechanism of trauma
– Affecting use of contrast
• Review portable CXR and pelvic XR
– Anything obvious been treated?
– Signs of aortic injury present? Does patient
also need chest CT?
– Pelvic fracture? If yes, is hematuria present?
Does patient need CT cystography?
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Patient Preparation for CT
• Hemodynamic – must be stable
• NPO – should not wait
• IV contrast – a must (if conditions allow)
• Oral contrast – no need for routine cases
• Rectal contrast – no need for routine cases
• Renal function test – risk/benefit ratio
• Pregnancy test - yes
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CT Technique
• Do whole abdomen!
• No plain scan
• Phases of scanning
– With pelvic fractures: late arterial and portovenous
whole abdomen
– Without pelvic fractures: Late arterial upper and
portovenous whole abdomen
– + delays at site of injuries
• If suspicion of TL spine fx, do small FOV axials
and coronal/sagittal reformations
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CT Technique
• Helical mode. Thinnest collimation possible and
reformatted to 2-2.5 mm for viewing
• 120 kV
• Auto MA based on patient size
• Lower dose for non-standard phases (i.e., late
arterial, delayed)
• Must have coronal and sagittal reformations
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Specific Questions
• R/O bowel injuries
– Oral, IV, rectal contrast
• Penetrating trauma
– Oral, IV, rectal contrast
• R/O bladder injuries (gross hematuria + pelvic
fractures = a must do)
– CT cystography using 300-400 cc of 2% contrast
instilled through a bladder catheter and image the
pelvis
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Concerns of CT
• Radiation dose can be reduced by
– Routine use of automatic tube-current modulation
– Reduce Z-axis (no plain scan or unnecessary delayed
scan)
– Use of Adaptive Statistical Iterative Reconstruction
• Maximize cost/benefit ratio
– Use of clinical prediction rule, expert recommendation
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Free Fluid: Type?
• Always measure HU
• Fluid does not
enhance! Changes in
attenuation from pre
to post contrast may
be seen but should be
minimal (<5-10 HU)
Type HU
Blood (acute) 30-45
Blood (clot) 50-60
Contrast (IV, oral, rectal) 100+
Clear fluid (urine, ascites,
bile)
<15
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Sentinel Clot Sign
• Blood accumulates adjacent
to site of bleeding
• Indirect sign of injury to an
adjacent organ even if the
lesion could not be
identified
• Orwig D and Federle MP*
– Sentinel clot seen in
84% of visceral injuries
– Sentinel clot only clue to
bleeding source in 14%
• The rest, CT showed
injury itself (86%)
Orwig D and Federle MP. Am J Roentgenol 1989;153:747
Denser fluid
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Free Fluid: Volume
• You can estimate volume
of blood but this is less
important than
hemodynamic status
• Each compartment:
Morison, perihepatic and
perisplenic, paracolic
gutters, pelvis
Amount
(cc)
#
compartment
s with fluid
Minor 100-200 1
Moderate 200-500 2
Large >500 > 2
Becker CD et al. Eur Radiol 1998;8:553.
Intraperitoneal Fluid Quantity
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Free Fluid: Volume
• Difficult to quantify
volume in
retroperitoneal bleed
Amount CT Character
Minor Fascial thickening
Moderate Confined to retroperitneal
space adjacent to its
origin (ie, perirenal,
anterior/posterior
pararenal)
Large Multiple communicating
retroperitoneal spaces
Retroperitoneal Hemorrhage Quantity
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Active
Extravasation
• Jet or focal area of
hyperattenuation (within 10 HU
of adjacent major vessel
source) within a hematoma on
initial images that fades into an
enlarged, enhanced hematoma
on delayed images
• Indicates significant bleeding
• Must be quickly communicated
to the clinician (surgical or
endovascular Rx may be
necessary)
Delayed
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Pseudoaneurysm / AVF
• Contained by connective tissue or vessel wall (ie, adventitia).
• Adjacent to a vessel
• Does not enlarge. Same size in all phases
• CECT not reliable to differentiate the two
• >70% of pseudoaneurysms progress to rupture but natural history of AVF is
uncertain
Pseudoaneurysm
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Active Extravasation vs.
Pseudoaneurysm
Characters Active Extravasation Pseudoaneurysm
Edges Ill-defined Defined
Shape Commonly a jet (linear or
layering); may be diffuse
or focal
Often round or oval; possible
neck adjoining artery
Delayed
appearance
Increased attenuation or
size; possible layering
Less apparent; in isolation,
no change in size, similar
attenuation with vessels
Management Urgent embolization or
surgery if significant injury
present*
Urgent or ambulatory
embolization or surgery if
significant injury present*
*Not all injuries must be treated. Small pseudoaneurysms or those amenable to Rx by direct pressure do not
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Hypoperfusion Complex
• Flat IVC, small aorta
• Enhanced: adrenals, kidneys, GB
mucosa, bowel mucosa
• Hypoenhanced: liver, spleen,
pancreas, peripancreatic edema
Flat IVC, small aorta, hyperenhanced kidneys, hyperenhanced GI mucosa, and
peripancreatic edema caused by hypoperfusion state from left pelvic ring injury
Flat IVC
HyperenhancedGImucosa
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Liver and Gallbladder
• Common
• Can be part of RUQ/midline “package injuries”
– Shearing right lobe adjacent to hepatic veins
– Compression left lobe
• Vast majority managed nonoperatively
– Surgery if severe injuries with active bleeding and/
or complete destruction of entire hepatic lobe
• Right lobe (75%) > left lobe
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Splenic Injury
• Most frequently affected organ in blunt trauma (?)
• Contusion, parenchymal laceration, subcapsular
hematoma, perisplenic hematoma, fragmentation
of parenchyma and disruption of hilar vessels
• Left lower rib fractures frequently associated
• Perfusion defects due to segmental
devascularization from vascular pedicle injury can
be difficult to distinguish from contusions or local
reactive hypoperfusion in hypotensive patient
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• Subcapsular hematoma = lenticular shape with
compression of adjacent splenic paenchyma
– Difficult to confidently see splenic capsule
– Sometimes difficult to distinguish btw subcapsular and
perisplenic hematoma
Image from Radiology.cornfield.org
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Nonoperative Management of
Splenic Injury
• Now accepted practice: Success rate 95% in
children, 70% in adults
• Well-recognized complication = delayed splenic
rupture
– No reliable CT finding to predict risk of delayed
splenic rupture
– Even a normal CT cannot exclude possibility of
delayed splenic rupture
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Pancreas
• <2% of blunt abdominal trauma
• Up to 90% multiple organ injuries
• Contusion, superficial or partial laceration,
complete transection or disruption
• Can be difficult to diagnose clinically
– Delayed complications: recurrent pancreatitis,
fistula, abscess, hemorrhage
– Risk of abscess/fistula high (25-50%) if duct
disruption (vs. 10% if duct not disrupted)
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Pancreas
• Predict the presence or absence of ductal
disruption by depth of laceration and
location
– Grade A, pancreatitis or superficial laceration
(<50% pancreatic thickness)
– Grade B, deep laceration (>50% thickness) at
tail
– Grade C, deep laceration at head
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• Direct CT signs: Pancreatic enlargement, focal linear non-
enhancement, comminution, heterogeneous enhancement (subtle
initially)
• Indirect CT signs: Peripancreatic fat stranding, fluid collections, fluid
separating splenic vein from parenchyma, hemorrhage, and
thickening of left anterior pararenal fascia
Focal linear non-enhancement
Focal linear non-enhancement
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Bowel and Mesentery
• 3-7% of blunt abdominal trauma
• Jejunum and ileum (near point of fixation—IC
valve and ligament of Treitz) most common
• Colon: transverse, sigmoid and cecum
• Stomach-rare
• Duodenal injury: 2nd/3rd part in close proximity
to spine
• Overall CT sensitivity/specificity 85-95%
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• Direct CT signs: 1) Discontinuity of wall, spillage of contrast or
luminal contents into peritoneal or retroperitoneal. 2) Extraluminal air
(definite for blunt trauma but not for penetrating trauma)
• Indirect CT signs: 1) Focal bowel wall thickening, streaky
mesenteric fat, unexplained free fluid between mesenteric loops. 2)
Generalized bowel wall thickening nonspecific
Colonic contrast leakage
Perforation site at sigmoid colon
Bullet
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• Duodenal perforation vs. hematoma
– Perforation immediate surgery
– Hematoma conservative
• Helpful if you can give oral contrast immediately before
scanning to see leakage
Perforation site
Circumferential wall hematoma
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• Mesenteric injury
– Extravasation of contrast (active bleeding)
– Intramesenteric fluid collections, hemoperitoneum,
thickening bowel loops in bowel ischemia
Initial scan
Delayed scan with
progressive increase of
extravasation
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Adrenal Glands
• 2% of blunt trauma cases undergone CT
• Usually unilateral, right sided and a/w
ipsilateral intraabominal and thorax injuries
• Majority not clinically significant
• Spontaneous resolution in 2 months
• Specific Rx may be needed if: large
hematoma compressing IVC, bilateral
hematomas result in adrenal insufficiency
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• Round or ovoid, stranding of perirenal/periadrenal fat
• Active bleeding due to injuries to suprarenal arteries
• F/U CT in 2-3 months to ensure resolution if unable to differentiate from
pre-existing adrenal mass on trauma CT
Active contrast extravasation in adrenal hematoma
PortovenousArterial
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Kidney and Ureter
• Kidney injury = most common RP injury
• Contusion, laceration, subcapsular hematoma,
shattered kidney, renal artery occlusion
• Major renal hemorrhage with minor trauma
should raise suspicion of underlying pathology
(hydronephrosis, cyst, horseshoe kidney, AML,
RCC)
• Macroscopic hematuria + stable urethral
injury excluded then CT
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• Laceration: linear or wedge-shaped hypodense area
– Fracture = involving medial and lateral surface of kidney through hilum
– Shattered kidney = laceration crossing kidney resulting in multiple fragments
Initial Delayed
Laceration
Active extravasation
hematoma
hematoma
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• Occlusion of main renal artery (subintimal tear with
subsequent thrombosis) or arterial avulsion
• Cortical enhancement due to patent capsular arteries
originating proximal to occlusion should always raise
suspicion of injury to main renal artery
No enhancement
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Urinary Bladder
• Most pelvic visceral injuries = bladder and
urethra
• Gynecologic injuries rare after blunt trauma
• Urinary bladder 8% of patients with pelvic fx
• Indicators of bladder injury
– Macroscopic hematuria
– Pubic rami fractures
– Hemorrhagic shock upon admission
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• Extraperitoneal rupture
– Direct perforation by bony fragment, rupture of pubovesical
ligament near bladder neck after symphysis injury or contusion
of distended UB
– Often involves anterior bladder wall near neck
– Conservative Rx
Bladder contrast in anterior perivesical space
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• Intraperitoneal rupture
– More frequently caused by direct perforation of bone fragment (>
rupture of distended bladder)
– Plugged by omentum or bowel loops making it difficult to detect
– Surgical Rx
Perforation site
Low-density free fluid
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CT Cystography
• Antegrade bladder filling by excretion of IV
contrast is NOT enough to exclude bladder
injuries
• Absolute indication: pelvic fracture + gross
hematuria
• Technique: 300-500 cc of diluted (2%) contrast
instilled through a bladder catheter using gravity
drip, scan pelvis, drain bladder
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Conclusion
• Trauma to abdomen “torso” often in setting of
multisystem injury
• Choice of imaging depends on hemodynamics
and imaging availability
• CT is the cornerstone in evaluation of stable
patients (impacting management and reduced
mortality)
• Tendency toward non-operative management
makes use of CT for monitoring
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Conclusion
• Must know: free fluid, active extravasation,
hypoperfusion complex
• IV contrast needed to assess solid visceral
organ and vascular injuries
• Oral and rectal contrast may be needed in
penetrating abdominal trauma
• Antegrade filling of bladder is not enough to
image of suspected bladder injury.