Multi detector CT in Blunt abdominal trauma . Spleenic injury, Liver injury, Kidney injury, Diaphragmatic injuruies, Pancreatic and duodenal injuries, Hypoperfusion complex, Retroperitonal Hemorrhage, Bowel and Mesentric injuries

1. Imaging in Blunt Trauma
Abdomen - I
Dr. D. Sunil Kumar

2. Mechanisms of Injury
• The most common causes of blunt abdominal
trauma are motor vehicle collisions, falls from
height, assaults, and sports accidents
• Three basic mechanisms explain the damage
to the abdominal organs:
– Deceleration
– external compression
– crushing injuries

3. • In approximate order of frequency, the most
commonly injured abdominal organs are the
spleen(25%), liver, kidneys, small bowel
and/or mesentery, bladder, colon and/or
rectum, diaphragm, pancreas, and major
vessels
• Multiple organs are often affected
simultaneously.

4. Multidetector CT Technique
• IV contrast with portal phase imaging maximize
detection of parenchymal injuries.
• Oral contrast material is no longer advised.
• Rectal contrast is occasionally used to detect
colorectal injuries in patients with perineal
lacerations and/or penetrating flank injuries.
• Delayed imaging of kidneys during urographic
phase is used to detect collecting system and
bladder injuries.
• Delayed imaging is also useful in specific
situations for differentiating between active
contrast extravasation from vascular injuries

5. • Recently, there is growing evidence that
supports the addition of an arterial phase
series (25–30 seconds after injection) of the
abdomen and/or pelvis in selected trauma
patients:
– Severe mechanisms of injury
– who have a displaced fracture of the pelvic ring
• Arterial phase images facilitate
– detection of trauma to the major vessels
– vascular injuries of the solid organs that are not
apparent on portal venous or delayed phase
images.

6. Hemoperitoneum and Free Peritoneal Fluid
• Injuries to solid and hollow viscera commonly
have associated hemoperitoneum.
• Nonclotted blood (typical attenuation of 30–45
HU) tends to flow freely between contiguous
peritoneal recesses and may eventually fill the
cavity completely.
• Blood located adjacent to the source of the
hemorrhage is typically partially clotted and
tends to be higher in attenuation (45–70 HU); this
finding is termed the sentinel clot sign.
• The detection of a high-attenuation clot may be
facilitated by using narrow window settings.

7. Sentinel clot sign. (a) Contrast-enhanced CT image shows a sentinel clot secondary to
laceration along the fissure for the ligamentum teres (arrow), in the perihepatic space
and lesser sac. (b) Contrast-enhanced CT image obtained in a patient who was
undergoing anticoagulation therapy for a protein C deficiency shows a sentinel clot
(arrow) surrounding the spleen.

8. • Occasionally, the attenuation values of
hemoperitoneum may be less than 20 HU, for
example, in patients with a
– decreased serum hematocrit level,a
preexistenting anemia
– hemorrhage that is more than 48 hours old.
• The finding of free intraperitoneal fluid in the
absence of direct signs of solid or hollow
visceral injury poses particular challenges,
particularly in male patients.
• A thorough search for additional direct signs
of organ injury is critical in these cases.

9. Splenic Injuries
• The spleen is the most commonly injured organ
in blunt trauma.
• The traditional CT-based splenic injury scale
system was developed by the American
Association for the Surgery of Trauma (AAST) and
accounts for the size and location of splenic
lacerations and hematomas
• On CT images,
– splenic lacerations - linear defects
– Hematomas - relatively hypoattenuating geographic
areas in the parenchyma

10. Splenic laceration seen on contrastenhanced computed tomography scan
as linear irregular hypodense area (arrow).

11. Parenchymal haematoma (arrow)
seen on contrast-enhanced
computed tomography scan as
focal hypodense area within the
enhanced splenic parenchyma with
an intact capsule

12. • Subcapsular haematomas appear as an
elliptic collection of low-attenuation blood
between the spleen capsules and enhanced
splenic parenchyma that causes the
indentation or flattening of the underlying
spleen margin.
• Free intraperitoneal blood in the perisplenic
space does not cause this effect on the
underlying spleen parenchyma.

14. AAST Splenic Injury Scale (1994 Revision)

15. • However, this CT-based splenic injury grading
system has been found to be a relatively poor
predictor of patient outcome and, specifically,
has been shown to be a poor predictor of the
eventual success of nonsurgical management.

16. • In an effort to improve the ability of CT to help
predict successful nonsurgical management in
splenic trauma, several additional CT features
of splenic trauma are important
considerations.
• The presence of active hemorrhage and/or
contained vascular injuries
(pseudoaneurysms and arteriovenous
fistulae) increases the risk of failed
nonsurgical management.

17. Contrast Blush
• A contrast blush is defined as an area of high
density with density measurements
(Houndsfield Units) similar to the nearby vessel
(or aorta).
• The differential diagnosis is:
– Active arterial extravasation
– Posttraumatic pseudoaneurysm
– Posttraumatic AV fistula

18. • Active Hemorrhage:
– Persistant blush in delayed phase image
– grows larger with time on a delayed phase study.
– A contract blush that is beyond the borders of the
organ, must be extravasation.
• In a pseudoaneurysm or AV fistula the
contrast will wash away with the bloodstream
in delayed images.

19. Axial contrast-enhanced CT image in
a 19-year-old man who was in a
motor vehicle collision demonstrates
large splenic laceration
with active hemorrhage seen
emanating from the splenic injury
into the peritoneal cavity (arrows).
Note large degree of
hemoperitoneum related to
this grade V splenic injury. Patient
underwent emergent splenectomy
beyond the borders of the organ

20. Contrast-enhanced axial CT scans
in 34-year-old man involved in motorcycle
accident. Transverse images in, A, arterial, B,
portal venous, and, C, delayed phases show
hyperattenuating contrast material (arrow)
that persists and progressively enlarges at
subsequent delayed imaging. Findings were
consistent with active extravasation. Patient
underwent splenectomy.
persists and progressively enlarges

21. Contrast blush washed out in delayed Phase

22. • Recently, a multidetector CT–based scale
system that includes contained vascular
injuries and active bleeding as part of the
grading criteria has been proposed to improve
the accuracy of predicting the need for
intervention, as compared with the traditional
AAST scale.

23. In the new system, patients with grade 4 injuries are candidates for splenic
arteriography or splenic surgery.

24. Hepatic Injuries
• Similar to the approach to splenic trauma
imaging, the AAST liver injury scale is
commonly applied when assessing the
severity of the acute hepatic injury.
• The liver injury scale is based on the presence,
location, and size of liver lacerations and
hematomas, as well as the presence of more
extensive tissue maceration or
devascularization in higher-grade injuries.

25. • Lacerations are the most frequently identified
injury pattern in liver trauma and are
identified as predominately linear branching
hypoattenuating areas.

26. • Lacerations that extend to the posterosuperior
region of segment VII, the bare area of the
liver, may be associated with retroperitoneal
hematomas around the IVC and accompanied
by adrenal hematoma.
• Lacerations that extend to the porta hepatis
are commonly associated with bile duct injury
and are thus likely to lead to the development
of a biloma.

28. Subcapsular hematoma. Contrast-enhanced
CT scan shows multiple subcapsular hematomas
in the right and left hepatic lobes (arrows). Multifocal
intraparenchymal hematomas are also seen (arrowheads).

29. Intraparenchymal hematoma. Contrastenhanced
CT scan shows a 5-cm intraparenchymal
hematoma in the medial segment of the left hepatic
lobe (arrow). Arrowheads indicate associated hemoperitoneum
in the right subphrenic space

30. Contrast-enhanced
CT scan shows active arterial bleeding
(arrows).

31. • Additional imaging findings that have been
found to be useful in guiding clinical
management decisions include
– (a) extension of the injury to involve the major
hepatic veins, which usually requires surgery to
control ongoing hemorrhage
– (b) the presence of active bleeding into the
peritoneal cavity
– (c) the presence of a large hemoperitoneum

32. Major Hepatic Venous Injury
• Major hepatic venous injuries are suspected if
lacerations or hematomas extend into one or
more major hepatic veins or the IVC.
• Such lesions can be life threatening and are an
indication for surgical treatment.

33. Contrast-enhanced CT scan shows a laceration that extends into the IVC and cutoff of right
hepatic venous drainage (arrow). Hemorrhagic fluid is seen around the IVC.
Surgery revealed a laceration of the right hepatic vein.

35. Grade V hepatic injury. (20) Contrast-enhanced CT scan shows a large intraparenchymal
hematoma
and lacerations that involve the entire right hepatic lobe and the medial segment of the left
hepatic lobe.
(21) Contrast-enhanced CT scan shows a deep hepatic laceration that extends into the
major hepatic veins. Note the
discontinuity of the left hepatic vein (arrowhead), a finding that indicates laceration. This
finding was confirmed at
surgery.

36. Delayed Complications
• The growing trend toward nonsurgical
management of hepatic injuries has increased the
relevance and frequency of delayed
complications.
• These posttraumatic complications include
delayed hemorrhage, abscess, posttraumatic
pseudoaneurysm and hemobilia, and biliary
complications such as biloma and bile peritonitis
and are more common in patient with severe,
complex liver injuries

37. Bowel and Mesenteric Injuries
• Are rare, occurring in approximately 5% of
patients with severe blunt abdominal trauma.
• Delays in diagnosis as short as 8–12 hours
increase the morbidity and mortality from
peritonitis and sepsis.
• Hence, one of the most essential tasks for the
emergency radiologist is to recognize the
often subtle CT signs of bowel trauma.

38. • At least one-half of injuries to hollow viscera
involve the small bowel(most commonly are
the proximal jejunum and the distal ileum),
followed in frequency by the colon and
stomach.
• Patients with a Chancetype vertebral fracture
and large abdominal wall hematoma have a
higher risk of injury to the bowel or
mesentery.

39. CT Findings
• Specific signs of Bowel Injury
– bowel wall discontinuity
– extraluminal contrast material
– Free intraperitoneal or retroperitoneal air
• The less specific (but more sensitive) CT signs of
bowel trauma include
– unequivocal focal wall thickening
– abnormal bowel wall enhancement
– Mesenteric foci of fluid, air, or fat stranding may be
secondary to bowel injury alone.
– free intraperitoneal fluid

40. • Unfortunately, the more specific signs are not
highly sensitive, and the more sensitive signs
are not highly specific.
• However, the presence of a combination of
these findings increases the likelihood of a
clinically important injury

41. Axial CT images show a defect in the proximal jejunum (arrow in a) and a mesenteric
hematoma in the left upper quadrant (arrow in b). Although no free air was seen on CT
images, a blowout perforation in the antimesenteric aspect of the proximal jejunum was
found at surgery. No mesenteric injury was described in the surgical report.
bowel wall discontinuity

42. • Extraluminal gas is a highly suggestive, but not
pathognomonic, sign of bowel perforation.
The amount of free gas varies widely.
• CT images should routinely be reviewed with
lung or bone window settings, in addition to
the routine soft-tissue settings for detection
of small gas collections.
• All phases should be reviewed because, on
occasion, pneumoperitoneum may appear
only on delayed images.

43. • Retroperitoneal air is seen with duodenal
injury or injury to the retroperitoneal aspect
of the ascending or descending colon

44. • Causes of pneumoperitoneum without bowel trauma
include
– intraperitoneal rupture of the urinary bladder with an
indwelling Foley catheter
– massive pneumothorax
– barotrauma
– benign pneumoperitoneum (eg, as observed in some
patients with systemic sclerosis)
– occasional diagnostic peritoneal lavage.
• “Pseudopneumoperitoneum,” air confined between
the abdominal wall and the parietal peritoneum, is
another potential cause of a false-positive diagnosis of
bowel rupture. This finding may be seen with
extraperitoneal rectal injuries, rib fractures,
pneumothorax or pneumomediastinum.

45. Bowel Wall Thickening
• Isolated, localized, unequivocal bowel wall thickening
may be indicative of nonsignificant bowel injury like
contusion or highly suggestive of a surgically important
injury, such as
– Hematoma
– ischemia secondary to mesenteric vascular trauma
– Perforation
• The likelihood of a focal bowel abnormality representing
an injury that requires surgical intervention increases
when found in association with
– pockets of fluid in the adjacent mesentery
– free fluid in the peritoneal cavity.
• Diffuse bowel wall thickening is usually not a result of
direct trauma but more likely related to the
hypoperfusion complex (“shock bowel”)

46. Abnormal Bowel Wall Enhancement
• Increased bowel wall enhancement may
represent bowel injury with vascular
involvement or may be part of the
hypoperfusion complex.
• This is due to increased permeability due to
hypoperfusion, which may result in interstitial
leakage of contrast material.
• Areas of decreased or absent contrast
enhancement are indicative of ischemic bowel

47. Bowel and mesenteric injuries in a 32-year-old woman after a motor vehicle accident. Axial
(a) and coronal (b) CT images show abnormal hyperenhancing thickened jejunal loops
(arrows in b) and high-attenuation foci of intraperitoneal fluid (arrowheads in a) consistent
with blood. No free or focal air was visible on CT images. At surgery, mesenteric tears in a
middle segment of the jejunum and a distal segment of the ileum were found, with
bleeding mesenteric vessels and multiple areas of perforation in the middle segment of the
jejunum and the proximal and middle segments of the ileum.

48. Axial source images also show a tear in the
abdominal wall on the right side (arrow in a)
and mesenteric fat stranding (arrow in b).
Oblique coronal image also shows unenhanced
small-bowel loops in the lower abdomen
(arrow in c). At surgery, shearing injury to the
small-bowel mesentery was found, with
active bleeding and with complete
devascularization and necrosis of a 90-inch
(229-cm) segment of the distal jejunum and
ileum and a perforation of the middle
jejunum.

49. • Intraperitoneal and Retroperitoneal Fluid.
• Without visible solid organ injury, the
presence of a moderate or large amount of
free fluid is a useful sign of bowel and/or
mesenteric injury and is a strong indicator for
exploratory laparotomy
• The location of the fluid may indicate the
location of injury.
• Retroperitoneal fluid may indicate injury of a
retroperitoneal segment of bowel.

50. Injury to the descending colon was suspected in view of fluid collection at the left
retroperitoneum (short arrow) and a thickened colonic wall (long arrow). Compare to
the normal fat density surrounding the right ascending colon (open arrow). Serosal
tear of the descending colon was proven at surgery.

51. • Specific signs of Mesenteric injury
– extravasation of intravenous contrast material
– abrupt termination and beading of vessels
Less specific findings include:
Mesentric hematoma
Mesenteric Infiltration
Bowel features
– Mesentric injuries may be associated bowel ischaemia
or infarction due to disruption of blood flow.

52. • Mesenteric Extravasation:
(a) Coronal CT image showsan unenhanced
segment of small bowel, a feature consistent
with a bowel infarct (arrow). (b, c) Axial images
show mesenteric extravasation (arrow in b),
mesenteric hematoma (arrow in c), and
thickening and hypervascularity of the proximal
jejunum (*). At surgery, an extensive small-bowel
mesenteric tear was found, with active bleeding
from a jejunal branch of the superior mesenteric
artery

53. • Mesenteric Vascular Beading and abrupt
termination:
– Appears as an irregularity in mesenteric vessels.
– indicative of vascular injury.

54. Axial CT image shows a change in caliber,
or beading, of some mesenteric vessels in the area of injury (arrows). At surgery, a tear
was found in the ileocecal
mesentery that warranted resection of the terminal ileum, cecum, and ascending colon.

56. Sagittal reformatted
image from abdominal CT
shows
lesser sac stranding (arrow)
and abrupt termination
of the left gastric artery
(arrowhead) at the
level of stranding.

57. • Mesenteric Hematoma
• Well-defined mesenteric hematoma indicative
of laceration of a mesenteric vessel.
• Although specific to mesenteric injury,
mesenteric hematoma does not always
indicate a need for surgery.
• Larger hematomas carry the risk of
subsequent bowel ischemia and usually
require surgical repair

58. Axial CT image shows a hematoma
surrounded by fat stranding (arrow) in the
splenic flexure mesocolon, with no evidence of active
bleeding. At surgery, a nonexpanding mesenteric hematoma
was found that did not require repair

59. Axial CT image shows a sigmoid mesenteric hematoma (arrow) and a normal appearance
of the sigmoid colon (arrowhead). A complete tear of the abdominal wall (*) is visible in
the right lower quadrant. Avulsion of the sigmoid colon mesentery associated with an
ischemic sigmoid colon segment (subsequently resected) was found at surgery.

60. • Bowel Injury
• bowel wall discontinuity
• extraluminal contrast material
• Free intraperitoneal or retroperitoneal air
• Mesentric Injury:
• extravasation of intravenous contrast material
• abrupt termination and beading of vessels
• Mesentric hematoma
• Common Findings:
• Free Fluid
• Mesentric fluid, fat stranding, haziness
• Focal abnormal bowel thickening/enhancement

61. • If there is no other explanation for intraperitoneal
fluid, bowel or mesenteric injury should be considered.
• Vast majority of bowel injuries have associated
abnormalities in the mesentery
• But Mesenteric injuries can be an isolated finding on
CT images.
• When nonspecific features of significant bowel or
mesenteric injury are the only CT findings, the need for
surgical intervention is highly dependent on clinical
judgment.
• Reevaluation with CT within 6–8 hours after the initial
evaluation may help to elucidate the significance of
such findings.

62. Pancreatic and Duodenal Injuries
• Severe anteroposterior compression trauma
against the spinal column from blows to the
mid–upper abdomen with a steering wheel or
bicycle handlebars are the typical mechanisms
that injure the pancreas and/or the
duodenum, often involving the left hepatic
lobe and spleen as well.

63. • The duodenum and pancreas are injured
simultaneously; isolated injuries are rare
(<30%).
• The morbidity and mortality associated with a
trauma to the duodenum and pancreas are
remarkably high.
• The probability of complications after
duodenal or pancreatic trauma ranges
between 30% and 60% and in many cases is
the result of missed findings or diagnostic
delays or both.

64. • CT diagnosis of pancreatic injuries shows
variable sensitivity and specificity because
many findings are subtle, absent, or at times
slow to develop.
• The neck and body of the gland are the most
common sites of injury
• The injured pancreas may appear normal on
CT images, particularly in the first 12 hours
after a trauma injury.
Pancreatic Injuries

65. • Direct findings:
– Laceration (linear region of nonenhancement)
– Diffuse or focal pancreatic enlargement
– Heterogenous enhancement
– Active hemorrhage from the pancreas
• Indirect findings:
– Peripancreatic fat stranding, fluid, hemorrhage
– Fluid between the splenic vein and the pancreas
– Injuries to adjacent organs or vessels
– Trajectory of penetrating injury through the region of
the pancreas
Imaging findings in pancreatic injuries

66. Pancreatic fractures or lacerations can be missed on the initial CT
images. Multiplanar reformation, thinslice axial image
reconstruction, or pancreatic parenchymal phase CT can be
beneficial to the quality of diagnosis

67. There is a linear focal area of
non-enhancement in the body
of the pancreas s/o laceration

69. (a) Axial contrast enhanced image and (b)
coronal reformation show pancreatic
contusion (arrow, a) as evidenced by a
focal region of hypoattenuation.There is also
mild peripancreatic hemorrhage (arrow, b).

70. Axial CECT image shows an extensive fracture
of the pancreatic neck with a large
intrapancreatic hematoma with active
extravasation (arrow).

71. Grading Pancreatic Injury
The integrity of the pancreatic duct is the most important factor in the
decision whether or not to operate.

72. Grade I pancreatic injury in a patient who experienced blunt abdominal trauma. Axial CT
image shows a minor contusion of the pancreatic body (black arrow). There is no
pancreatic duct injury and no active bleeding.

73. Grade III pancreatic injury. (a) Axial CT image shows diffuse edema of the pancreatic
parenchyma with some defined areas of contusion (black arrow). There is a
transection across the pancreatic body (white arrow).

74. Grade IV pancreatic injury. Axial CT images show a laceration of the pancreatic neck
(arrow) with a pancreatic duct injury

75. Grade V injury. Axial CT image (A) shows
massive disruption (arrowheads) of the
pancreatic head.

76. • MRCP, in addition to showing the course of the
pancreatic duct from the head to the tail, has the
added advantage compared with ERCP in
detecting pancreatic parenchymal abnormalities
and associated adjacent abnormalities, such as
concomitant biliary injuries, that may also go
undetected on initial trauma CT.
• The role of ERCP may be confirmatory in
indeterminate cases before definitive surgical
intervention or may play a therapeutic role when
stenting of the pancreatic duct is a feasible option
MRCP and ERCP

77. Pitfalls of Pancreatic Injury
• The most important pitfall is that CT findings
of pancreatic injury may be either absent or
subtle early after injury.
• Another pitfall in diagnosis of pancreatic
injury is the presence of peripancreatic fluid,
which may be related to either
– aggressive resuscitation efforts
– hemoperitoneum related to injuries of adjacent
organs.

78. • Isolated duodenal injuries are uncommon.
• CT findings are similar to those for injuries involving
other segments of the gastrointestinal tract and
include focal wall discontinuity, wall thickening,
periduodenal fluid, and extraluminal gas in the
retroperitoneum .
• Duodenal hematomas typically occur in younger
patients: Blood accumulates in the submucosal or
subserosal layer of the otherwise intact duodenal wall.
• Gastric outlet obstruction is a common complication of
duodenal hematomas, particularly in the early stages
after the injury.
• The management of isolated duodenal hematomas is
conservative
Duodenal Injury

79. Renal Injuries
• Approximately 10% of all significant blunt
abdominal traumatic injuries manifest with
renal injury, although it is usually minor.
• The presence of hematuria (gross or
icroscopic) after abdominal trauma is a good
predictor of the presence of a urinary tract
injury

80. Imaging Protocol
• Nonenhanced scan - helpful in detecting
intraparenchymal hematoma that may
become isoattenuating relative to the normal
renal parenchyma at postcontrast CT
• late cortical or early nephrographic phase -
allows identification of parenchymal injuries
• Delayed phase – collecting system injuries

81. • An AAST grading system is applied to classify
the severity of renal trauma based on the size
and location of renal lacerations and
hematomas.
• The majority of traumatic renal injuries are
treated conservatively with observation alone.
• Therapeutic interventions are reserved for
disruptions of the collecting system and for
vascular injuries.

86. • Grade 4 injuries:
• Lacerations involving the collecting system are
characterized by the extravasation of opacified
urine into the perirenal space.
• In all cases whenever significant perinephric
fluid is seen around the renal hilum on
nephrographic phase images, delayed
excretory phase images must also be
evaluated for urinary extravasation.

87. Right renal laceration extending into the collecting system (grade IV injury) in a 34-year-old
man who was involved in a motor vehicle accident. (a) Corticomedullary phase CT scan shows
a small amount of fluid along the posterior surface of the right kidney (arrow), a finding that
was the only clue to the presence of a laceration. (b) Delayed excretory phase CT scan shows a
subtle area of urinary extravasation (arrow).

88. • Segmental infarctions are caused by thrombosis,
dissection, or laceration of an accessory-capsular
artery or intrarenal segmental branch.
• At CT, they manifest as well-demarcated, linear or
wedge-shaped nonenhancing areas extending
through the renal parenchyma, with the base
oriented toward the renal capsule and the apex
pointing toward the hilum
• Contusions - blurred margins and enhance less
than the normal adjacent parenchyma.
• Segmental infarctions - better-delineated margins
and lack enhancement

89. Segmental infarction without associated
laceration (grade IV injury)

90. • Grade V injuries represent the most severe
type of renal trauma and include
– shattered kidney
– partial tears or complete laceration (avulsion) of
the ureteropelvic junction
– thrombosis of the main renal artery or vein with
devascularization of the kidney

91. • The differentiation of ureteropelvic junction
avulsion from incomplete tear is crucial, since
the former usually requires surgical repair,
whereas the latter may be treated
conservatively or with stent placement.
• Partial tears - presence of contrast
opacification in the ipsilateral ureter distal to
the point of injury
• Avulsion - absence of contrast opacification in
the ipsilateral ureter distal to the point of
injury

92. Portal venous phase CT scan shows right
hydronephrosis (*) and a small
amount of perinephric fluid near the
renal hilum (arrow). (b) Delayed
excretory phase CT scan helps confirm
the presence of posteromedial urinary
extravasation (arrows). The ureter distal
to the point of injury was seen to be
unenhanced.

93. a) Portal venous phase CT scan shows left
hydronephrosis (*) and a small
amount of perinephric fluid (arrow). (b, c)
Delayed excretory phase CT scans show
medial perinephric urinary extravasation
(arrow in b) and opacification of the distal
ureter (arrowhead in c).

94. • The most common form of vascular pedicle
injury is renal artery occlusion
• CT findings include a welldefined subtotal or
global absence of parenchymal enhancement
with no distortion of the renal contour.
• The abrupt termination of the renal artery at
the point of occlusion can be confirmed with
angiography but is sometimes seen on MPR
and maximum-intensity-projection images

95. a) Portal venous phase CT scan reveals a
geographic pattern of nephrographic
absence in the left kidney. The kidney shows
only small areas of faint enhancement in the
lower pole (arrows) and is
clearly hypoattenuating relative to the normal
right renal parenchyma. (b) Coronal
maximum-intensity-projection
image depicts the blind ending of the left main
renal artery (arrow).

96. • Isolated renal vein injuries are the most
uncommon type of vascular pedicle injury.
• Renal vein thrombosis virtually always occurs in
combination with arterial or parenchymal injury.
• Contrast-enhanced CT reveals an enlarged renal
vein containing a filling defect (thrombus) and
renal changes secondary to acute venous
hypertension including
– nephromegaly
– diminished nephrogram with delayed nephrographic
progression
– decreased excretion of contrast material into the
collecting system

97. Adrenal glands
• The adrenal glands are injured in
approximately 2% of patients who undergo
blunt abdominal trauma.
• Right adrenal is involved in 75% of cases, the
left adrenal in 15% and both adrenals in 10%.
• Unilateral adrenal hematomas usually resolve
spontaneously, without any sequelae.
• Bilateral hemorrhage rarely manifests as life
threatening adrenal insufficiency.

98. • On CT images, adrenal injuries typically
manifest as
– focal hyperattenuating hematomas
– glandular enlargement with ill-defined
haemorrhage confined to or extending outside of
the gland into the periadrenal or retroperitoneal
fat.
Abdominal
CT scan obtained with intravenous contrast
material
shows a right adrenal hemorrhage
(arrowheads) with
periadrenal hemorrhage (arrow).

99. Diaphragmatic Injuries
• Diaphragmatic injuries are caused by a sudden increase
in intra abdominal pressure.
• The rate of initially missed diagnoses on computed
tomography (CT) ranges from 12% to 63% and in most
such cases, the right hemidiaphragm is affected.
• Unfortunately, diaphragmatic rupture does not resolve
spontaneously, and the resultant complications may be
disastrous.
• A missed diagnosis can later present as intrathoracic
visceral herniation and strangulation with a mortality
rate of 30%–60%

100. Mechanism of Injury
• Blunt diaphragmatic injuries result from
considerable force and most often occur in
vehicular impact (90% of cases), a fall from a
height, or a crushing blow
• A lateral thoracoabdominal impact results in
distortion and anteroposterior elongation of the
chest wall, which may cause shearing of the
diaphragm or avulsion of its attachments.
• In a frontal impact (eg, against the steering wheel
of a car), an abrupt rise in intraabdominal
pressure is transmitted to the diaphragm by the
abdominal viscera

101. CT Signs
• These imaging findings include
– direct visualization of diaphragmatic discontinuity
– herniation of abdominal viscera into the thorax
– collar sign, a waist like constriction of herniated
abdominal contents through a diaphragmatic rent

102. The axial helical CT scan shows thickening and focal discontinuity of the left hemidiaphragm
on the anterior aspect (arrow).

103. CT image shows herniation of
the liver (L) into the thorax
through a diaphragmatic defect
(arrows). The diaphragmatic
segments that remain in place
are thickened (arrowheads)
(thickening of the diaphragm
sign).

104. Sagittal contrast-enhanced reformatted CT image shows left-sided BDR, depicted as a 3-
cm-long segmental diaphragmatic defect (arrowheads) through which a bowel loop (B)
bulges into the thorax. The hernia is evident from the waistlike constriction of the bowel
at the level of the diaphragm (collar sign). (b) The collar at the base of the herniated
bowel (arrowheads) is more difficult to detect on the axial CT image than on
reformatted images in other planes.

105. • The use of coronal and sagittal reformations
led to the description of two additional
variants of the collar sign:
– the hump sign, in which a rounded portion of the
superior liver herniates through the diaphragmatic
rent
– band sign, in which the torn free edge of the
diaphragm causes a linear indentation in the
herniated liver edge

106. Right-sided BDR in a 35-year-old man after a motor vehicle accident.
(a) Coronal maximum intensity projection image from contrast-
enhanced CT shows herniation of the liver dome through a
diaphragmatic rupture (hump sign), with a smooth collar sign
(arrows) and a linear area of subtle hypoattenuation (band sign)
(arrowhead) extending across the base of the defect. (b) Axial
contrast-enhanced CT image shows an area of hypoattenuation
(arrowheads) in the dome of the liver, a finding that might
correspond to the band visible in a.

108. • A high apex of the right hemidiaphragm could
easily be mistaken for a hump sign. To avoid
this error, an attentive search should be made
for an associated collar sign.
• In addition, the contours of the liver should
be carefully examined; they are not smoothly
rounded in the presence of BDR as they are in
the presence of an intact diaphragm

110. • Recently, the dangling diaphragm sign was described, a
conspicuous sign in which the free edge of the injured
diaphragm is seen to curl inwards and away from the chest
wall

111. Major Vascular Injuries
• Injuries to the aorta and other major
abdominal and pelvic vessels are uncommon
but highly lethal, owing to the rapid rate of
blood loss into the peritoneal cavity or
retroperitoneal spaces.
• Diagnosis of aortic transection on CT images is
obvious when accompanied by a large
hematoma or active extravasation of contrast-
enhanced blood.

112. • More subtle injuries, such as small
pseudoaneurysms, intimal flaps, or even
thrombosis may be very difficult to detect and
require a proper CT technique (often with a CT
angiographic phase) and a systematic review
of the images by the radiologist
• Blunt injuries to the IVC are very rare, with
only a few published reports in the literature

113. Aortic dissection in a 45-year-old man after a motor vehicle collision. Contrast-enhanced
CT image shows rapid deceleration injury leading to a focal dissection in the abdominal
aorta (arrow) with periaortic hemorrhage (arrowhead).

114. (a) Axial contrastenhanced CT image shows a filling defect (arrow) in the celiac artery,
consistent with an intimal injury. (b) Sagittal oblique CT angiogram shows a curvilinear
filling defect (arrow) sugg of intimal tear causing partial occlusion of the celiac artery.
There was no evidence of end-organ ischemia. Conservative management was chosen,
and repeat CT 2 days later showed resolution of the finding.

115. Retroperitoneal Hemorrhage
• The retroperitoneum can be the source of considerable
blood loss that can remain occult to clinical
examination and evaluation with FAST (focused
assessment with sonography for trauma)
• They may occur secondary to injuries to major vessels,
solid organs, hollow viscera, and/or the skeleton.
• The goals of imaging are to identify the retroperitoneal
hemorrhage, its
– Location
– possible source
– assess its relative stability on the basis of the size and
presence (or absence) of active extravasation of
intravascular contrast material

116. • From a surgical standpoint, the
retroperitoneum can be
divided into zones because
hematoma location has
therapeutic implications.
• Zone I is the central midline
retroperitoneum and contains
the abdominal aorta, the IVC,
the root of the mesentery, and
portions of the pancreas and
duodenum.
• Zone II is the lateral
retroperitoneum and contains
the kidneys, adrenal glands,
renal vasculature, and
ascending and descending
colon.
• Zone III is the pelvic
retroperitoneum

117. • Zone I retroperitoneal hemorrhage carries the highest risk of
vascular injury because the major abdominal vessels lie in this zone
Abdominal CT scan obtained with intravenous contrast material shows a large, central
midline retroperitoneal hematoma (arrowheads) with a large focus of active extravasation
(arrow) displacing the duodenum and pancreas anteriorly. (b) Coronal reformatted
CT image shows active extravasation of intravascular contrast material adjacent to the
central superior mesenteric vein (arrow), which proved to be lacerated and was repaired at
surgery.

118. Small zone I (central) retroperitoneal hematoma in a 41-year-old man who was involved
in a motor vehicle collision. Abdominal CT scan obtained with intravenous contrast
material shows a small amount of intermediate-attenuation fluid (arrowheads) between
the aorta and IVC, a finding that presumably represents venous hemorrhage.
The patient was observed clinically and remained hemodynamically stable.

119. • Renal injuries account for the majority of Zone
II hemorrhages.
• Many perirenal and pericolonic hematomas
are self limiting, and patients can be treated
with observation alone if they remain
hemodynamically stable and no signs of active
bleeding is seen.

120. Large zone II (lateral) retroperitoneal hematoma in a 17-year-old boy who was involved in
a highspeed motor vehicle collision. Contrast-enhanced CT scan shows right-sided
perirenal and posterior pararenal retroperitoneal hematoma (white arrowheads) from a
right renal laceration, with active extravasation of intravascular contrast material (black
arrow) from a renal parenchymal injury.

121. • Zone III encompasses the pelvic
retroperitoneum and is the most common
location of retroperitoneal hemorrhage,
frequently in association with pelvic fractures.

122. Hypoperfusion Complex
• CT hypotension complex refers to the
predominant abdominal imaging features that
occur in the context of profound hypotension.
• Early recognition is valuable before an
irreversible state of shock occurs in blunt
abdominal trauma.

123. Visceral findings
• Shock bowel
• Abnormally enhancing small bowel loops with increased
bowel wall thickness more than 10 mm is seen in
hypoperfusion complex
– on non-contrasted images, hyperdense walls compared to
the psoas muscle
– wall thickening is due to submucosal oedema
– hyperenhancing mucosa
• colon is less involved than small bowel because of the less
oxygen demand
• Diffuse dilation of fluid-filled bowel loops (>2.5 cm) is less
frequent.
• Reversible.

124. Shock bowel. CT scan showing intense mucosal wall enhancement of small bowel (small
arrow). Also seen is dense renal parenchymal enhancement

125. • Abnormal adrenal enhancement
• Intense and persistent enhancement of
adrenal gland is an important finding in
hypoperfusion complex
• Due to sympathetic overactivity in
hypovolemia, there is increased preferential
blood flow to adrenal gland as a
compensatory mechanism for hypovolemia
causing enhancement more than that of
adjacent IVC
• always bilateral

126. • Abnormal splenic enhancement:
• Spleen normally enhances more than liver.
• Splenic parenchymal enhancement less than
30 HU compared to liver in children and 20 HU
in adults should raise suspicion of
hypovolemia
• Splenic vascular pedicle injury may also show
splenic nonenhancement, however, it is
associated with additional findings like
perisplenic or intraparenchymal hematoma

127. contrast-enhanced abdominal CT scan demonstrates increased adrenal
gland enhancement (arrow head) and splenic hypoperfusion (thick
arrow).

128. • Abnormal pancreatic enhancement
• pancreas shows increased enhancement >20 HU
than liver.
• Peripancreatic fluid in absence of pancreatitis or
pancreatic injury is highly suggestive of
hypovolemic shock

129. • “White or black” kidney
• Intense and prolonged
enhancement of kidneys
(whitekidneys) is commonly
observed due to increased
glomerular efferent arteriolar
vasoconstriction secondary to
sympathetic activity that
results in contrast stasis.
• In later stages, kidneys may
show complete
nonenhancement, described
as “Black Kidney” by Catalano
et al. and it is an ominous
prognostic indicator
suggestive of serious patient
condition

130. Vascular manifestations
• IVC-flattening
• Flattening of IVC or slit
sign is one of the
earliest and consistent
finding
• Slit-like IVC measuring
– AP diameter <9 mm in
three consecutive
segments; i.e. 20 mm
both above and below
the renal veins and the
perihepatic portion

131. • “Halo sign”
• Accumulation of extracellular fluid around a
collapsed intrahepatic IVC that results in a
circumferential zone of hypoattenuation (<20
Hounsfield Units [HU]) is termed the halo sign

132. • Small aorta
• A diameter of <13
mm at 2 cm above,
at, and 2 cm below
the origin of the
renal artery is
suggested to
represent an
abnormal finding

133. • Abnormal
enhancement of
mesenteric vessels
• Narrowing of
superior
mesenteric artery
and vein with
intense
enhancement
similar to aorta and
IVC is also observed
in hypovolemia.

134. • Generally, the
presence of 2 or
more vascular or
visceral signs is
required to
establish the
presence of HSC.