1,:. CT in the Diagnosis : of Renal Trauma1 DaryiR
4
. ,,
,,,
.
Javier Brian
Fanney,
MD
Casillas, J. Murphy,
MD MD
Computed
tomography
agnostic
study
pecially
in
common. CT
scans
(CT)
in patients
large
trauma
In our
3-year
for
centers
abdominal
identified:
renal
laceration,
complete
iion,
fractured
nal
capsule,
renal
to the
small
vein
kidney
injury,
of each
The
lesion
with
artery
renal
kidney.
large
CT
renal
lesions
without
thrombosis, findings
are 2,500 hemato-
junction and
disrupan
intact
avulsion,
and
di-
es-
over
subcapsular
ureteropelvic
shattered
abnormal
injuries
traumatic
and
initial
trauma,
encompasses
following
laceration,
kidney,
and management U
contusion,
renal
multiple-system which
the
as the
or suspected
where
trauma,
mas,
employed
known
experience,
were
trauma
is frequently
with
clinical
reand
features
are reviewed.
INTRODUCTION
Renal injuries are classified into three categories. Category 1 lesions are relatively minor and are treated conservatively. Category 2 lesions are more serious injuries for which the type of therapy used depends on the amount of nonviable tissue, cxtent of hemorrhage, and presence or absence of extravasated urine. Category 3 lesions
are
catastrophic
injuries
that
require
The proper method of detecting, been debated. Computed tomography the entire spectrum of renal injuries modalities.
CT provides
precise
urgent
surgery.
staging, and managing renal trauma has long (CT) is capable of demonstrating virtually and has clear advantages over other imaging
anatomic
detail
of renal
injuries
that
otherwise
may be understaged on the basis of excretory urographic or angiographic findings. In addition, CT effectively reveals predisposing renal abnormalities and provides valuable information about other intraabdominal structures. The appearance of various renal injuries on CT scans are illustrated, and the clinical parameters and therapeutic implications (1 1 6) are reviewed. -
Index
terms:
Kidney,
RadloGraphics I
From
1990;
the
Department
CT,
8 1. 1 2 1 1
©RSNA,
Hospital,
3800
injuries,
81.41
10:29-40 of Radiology,
Miami. From the 1988 RSNA nal revision received October versity
#{149} Kidney,
Reservoir
University
annual meeting. 20. Address Rd, NW,
of Miami
School
Received March reprint requests Washington,
of Medicine 23, 1989; to D.R.F.,
DC 200072
and Jackson
accepted Department
and
Memorial
Medical
Center,
revision requested April of Radiology, Georgetown
19; fi. Uni.
197.
1990
29
Figure 1. Renal contusion. (a) CT scan shows delayed excretion tamed i week later (not shown) was normal. (b) On the drawing in the renal pelvis indicates absence of excretion.
U CATEGORY 1 INJURIES Although renal injuries occur in 1 0% of patients who sustain blunt abdominal trauma, 75%-85% of these injuries are minor and are treated nonsungically. Category 1 lesions in-
dude mental capsular
contusions,
intrarenal
infarctions, hematomas.
and
small
hematomas, isolated
segsub-
#{149} Renal Contusion A renal contusion is diagnosed when there delayed excretion of contrast medium (Fig i). The proposed cause of the radiologic finding is delayed tubular transit time secondary to edema. The abnormality may be global on segmental. Renal function invariably returns to normal within i week without sequelae.
30
U
RadioGrapbics
U
Fanney
et a!
in the right kidney. Repeat scan obof this injury, absence of cross-hatching
#{149} Intrarenal An
intrarenal
as a focal
Hematoma hematoma
renal
lesion
appears that
on
does
not
CT
scans
enhance
after administration of contrast material (Fig 2a) . These lesions are poorly marginated and may extend to the renal capsule. On scans obtained without contrast material enhancement, the hematoma is seen as an area of high attenuation relative to that of the renal parenchyma (Fig 2b).
is
#{149} Segmental
Infarction
A traumatic segmental infarction may from occlusion of intrarenal (interlobar
result or
arcuate) or polar arterial branches. It may be distinguished from an intrarenal hematoma by its sharply marginated wedge-shaped appearance (Fig 3). The affected area will later be transformed into a deep scar as the infarcted tissue is resorbed.
Volume
10
Number
1
Figure 2. Intrarenal scan taken without
hematoma. (a) contrast medium
CT
shows a poorly defined high-attenuation region in the right kidney (arrow), a finding representing acute hemorrhage. (b) On CT scan obtained after contrast
medium administration, the hematoma low in attenuation relative to the enhanced renal parenchyma. (C) Drawing of intrarenal hematoma.
is
b. Figure in the
January
3. Segmental infarction. left kidney (arrow). (b)
1990
(a) CT scan shows Drawing of corresponding
a wedge-shaped injury.
area
of low
attenuation
Fanney
et a!
U
RadioGrapbics
U
31
Figure 4. Small row). (b) Drawing
#{149} Small
subcapsular
hematoma.
(a)
CT scan
Subcapsular
Hematoma
A subcapsular hematoma is diagnosed when hemorrhage is confined to the immediate cxtrarenal area by the renal capsule (Fig 4). The fluid collection may be lenticular, and its presence is delineated by flattening of the kidney and separation from Gerota fascia by fat. U
CATEGORY
demonstrates
small
2 INJURIES
Category II lesions represent an intermediate degree of renal trauma, which includes injuryto the collecting system. These lesions may be treated conservatively or surgically, depending on clinical status of the patient
U
RadioGrapbics
U
in the
left
kidney
(ar-
and nadiologic assessment. CT has greatly influenced the management of these lesions, since it can accurately depict the extent of injury.
#{149} Large
Subcapsular
Fanney
et a!
Hematoma
Large subcapsular hematomas usually have a lenticular shape (Fig 5). The attenuation of the hematomas on CT scans may range from high (acute hematoma) to low (chronic hematoma). Large subcapsular hematomas may result in rare complications, such as infection or hypertension secondary to parenchymal compression, the so-called Page kidney. Evacuation of the hematoma surgically or percutaneously is appropriate in these cases. #{149} Corticomedullary Corticomedullary renchymal tears with the collecting juries are usually less hemorrhage
32
hematoma
of the lesion.
Laceration lacerations are deep pathat do not communicate system (Fig 6). These intreated conservatively unis severe.
Volume
10
Number
1
a. Figure denting drainage.
b. 5.
Large subcapsular hematoma. the right renal parenchyma. This (b) Drawing of the injury.
a. Figure 6. Corticomedullary ated with an acute perirenal (b) Drawing of corresponding
January
1990
laceration. hematoma. injury.
(a) CT scan shows a large subacute subcapsular fluid collection became infected and required
b. (a) CT scan shows a corticomedullary After conservative treatment, the patient
hematoma percutaneous
laceration recovered
Fanney
et a!
in-
(arrow) associuneventfully.
U
RadioGrapbics
U
33
Figure sation
7. Complete renal laceration. of contrast medium (arrows).
(a)
(b)
CT scan
Drawing
Figure 8. Renal fracture. (a) CT scan shows well perfused. Surgical repair was performed.
#{149} Complete
Renal
shows
of renal
deep
Laceration
RadioGrapbics
U
Fanney
et a!
left
kidney
with
extrava-
The
fragments
remain
plications. The improved contrast resolution and tomographic nature of CT allow superior detection of urine extravasation.
#{149} Renal
Fracture
A renal fracture is seen on CT scans as a single transection of the kidney into two poles, accompanied by extravasation of urine (Fig 8). These fractures often occur along intenlobar divisions, resulting in preservation of arterial blood supply. Thus, successful reconstruction
U
in the
b. a fracture of the left kidney (arrows). (b) Drawing of renal fracture.
Complete renal laceration is a focal parenchymal injury that extends into the collecting system and results in extravasation of opacified and nonopacified urine (Fig 7). Communication between the collecting system and penirenal hematoma may result in urinary obstruction due to clot, a situation that can lead to deterioration and late corn-
34
laceration
laceration.
is possible
in many
cases.
Volume
10
Number
1
a. Figure
b.
Disruption of the ureteropelvic junction. (a) travasation of opacified urine. Renal parenchyma is intact. picts extravasation of urine from disrupted junction.
a. Figure heads) ment,
9.
10.
Shattered
with well-perfused the patient recovered
#{149} Disruption Junction Disruption occur
of of the
after
an
event
(Fig
9).
urine
without
proper
kidney
diagnosis.
with
contained
fragments (K) uneventfully.
fragments.
(a)
1990
b. CT scan
junction
may
Extravasation
of opacified
parenchymal
injury
is a clue
to
was
shows
#{149} Shattered
acceleration-deceleration
an enlarged
repair
right
kidney
performed.
multiple
(b)
with
Drawing
lacerations conservative
(C). After injury.
Kidney
with
cxde-
(arrowtreat-
Contained
Fragments A shattered kidney with contained fragments is demonstrated by CT as multiple lacerations of the renal parenchyma with an intact renal a special
treated
January
shows
Surgical
contained by the renal capsule (b) Drawing of corresponding
Ureteropelvic
ureteropelvic
CT scan
capsule
(Fig
category
i 0).
This
2 lesion,
injury which
represents may
be
nonsurgically.
Fanney
et a!
U
Ra4ioGrapbics
U
35
a. Figure 11. Renal vein thrombosis. (arrow) is present in the right renal bus in the renal vein.
b. (a) CT scan shows delayed excretion vein, extending to the inferior vena
a. Figure 12. Shattered kidney with disrupted capsule is torn, and blood (H) extends into (b) Drawing of the injury.
fragments. the
perirenal
(a)
in the right kidney. A thrombus cava. (b) Drawing depicts throm-
b. CT scan shows
space
(arrows)
#{149} Renal
Vein
. A
shattered left kidney (K) . The nephrectomy was performed.
Injury
Renal vein injury occurs in 20% of patients with solitary pedicle injury (Fig ii). These lesions have a better prognosis than arterial injuries. the renal traumatic managed
36
U
RadioGrapbics
U
Fanney
et a!
Although laceration or avulsion vein requires immediate repair, renal vein thrombosis may be nonsurgically.
Volume
10
Number
of
1
Figure 13. Renal artery occlusion and thrombosis. (a) CT scan shows nonperfusion of the left kidney. The renal pedicle is seen (arrow). (b) Arteniogram definitively demonstrates the presence of a renal pedicle injury. (c) Drawing depicts the renal artery thrombus.
#{149} Renal Artery Occlusion Renal artery occlusion results from an acceleration-decelenation event, which causes intimal tear, subintimal dissection, and thrombosis (Fig 13). The ischemic kidney fails to opacify after administration of contrast medium. Collateral circulation may contribute to a “cortical rim” of enhancing parenchyma.
C.
U
CATEGORY
Category
3 lesions
3 INJURIES constitute
5% of renal injuries and include renal pedicle injuries and shattered kidneys with disrupted fragments. These lesions require urgent surgery. Prompt diagnosis by means of CT allows successful reconstruction
in some
cases.
#{149} Shattered
Kidney
with
#{149} Renal Artery Avulsion Renal artery avulsion results from tearing of the musculanis and adventitia (Fig 14). CT is superior to arteniography, since it allows this more life-threatening injury to be distinguished from renal artery occlusion.
Disrupted
Fragments A shattered kidney with disrupted fragments results from violation of the renal capsule (Fig 12). Conservative therapy results in frequent short-term and long-term complications. Therefore, nephnectomy is the preferred treatment.
January
1990
Fanney
et a!
U
RadioGraphics
U
37
a.
b. Figure 14. Renal artery avulsion. (a) CT scan shows nonperfusion of the right kidney with rim enhancement (white arrows). A large right penirenal hematoma and a small left perirenal hematoma (black arrow) are present. (b) Arteriogram shows interruption of the right renal artery. (C)
Drawing
of corresponding
injury.
C-
U ABNORMAL KIDNEY TRAUMA Preexisting congenital on acquired renal abnormalities are well known to predispose individuals to renal injury, even in the setting
of relatively minor trauma. Among these abnormalities are congenital anomalies such as horseshoe and pelvic kidney, hydronephrosis, tumors, and simple cysts. CT is extremely valuable in detection of the abnormality, which in turn may alter therapeutic management.
e 15. Ruptured angiomyolipoma. t. f scan demonstrates underlying renal mass with attenuation equal to that of fat (arrows). There is associated
hemorrhage.
For patient
example, not all renal hemorrhage who has sustained trauma may
solely cell
to
injury.
propensity trauma, surrounding
38
U
RadioGrapbics
U
Fanney
et a!
Angiomyolipomas
carcinomas
are to
CT
vascular
hemorrhage.
revealed
and tumors In a case
extensive
a low-attenuation
Volume
in a be due renal
with
a
of minor
hemorrhage mass
10
(Fig
Number
15).
1
Figure
16.
Hemorrhagic
simple
shows high-attenuation ney. Note low-attenuation
fluid
cyst.
CT scan
within the right kidfluid in the periphery
Figure
18.
abdominal
(arrows).
U
.-.
Pseudosubcapsular
scan shows apparent tomas (arrowheads).
wall
PITFALLS
hematoma.
bilateral subcapsular Note duplication
musculature
CT
hemaof anterior
(arrows).
INTERPRETATION an important imaging IN
CT has become
modal-
in the evaluation of renal trauma. As a consequence, the radiologist must be familian with several misleading appearances in order to prevent erroneous diagnoses. Potential pitfalls include anatomic variations and various artifacts. ity
#{149} Renal
Pseudofracture
Renal pseudofracture is produced on CT scans by sectioning through the hilar lip of the kidney (Fig 1 7) . The characteristic location of the “fracture” and absence of penirenal fluid are clues to the correct diagnosis. Figure 17. cleft (arrow) right kidney.
A ruptured
Renal pseudofracture. in the posteromedial There is no perirenal
angiomyolipoma
CT scan shows aspect of the hematoma.
was found
at
surgery. CT is also valuable in distinguishing a ruptured or leaking simple cyst from hemorrhage. In one case, the CT scan showed both a high-attenuation fluid, representing marked hemorrhage into a renal cyst, and a low-attenuation fluid, representing leakage from the cyst (Fig 16). A renal cyst was discovered at surgery.
January
1990
#{149} Pseudosubcapsular
Hematoma
Pseudosubcapsular hematoma appears as apparent region of low attenuation along surface of the kidney (Fig 18). This artifact created by respiratory motion during data quisition. Recognition of a similar phenomenon in the anterior abdominal wall allows proper diagnosis. The artifact is confirmed when the low-attenuation area is not seen adjacent or repeat scans.
Fanney
et a!
U
an the is ac-
on
RadioGrapbics
U
39
#{149} Streak
Artifact
Streak artifacts from the urographic contrast medium may be misinterpreted as a collecting system injury (Fig 1 9). When these artifacts are associated with a penirenal hematoma, an erroneous diagnosis of a complete renal laceration may lead to unnecessary
surgery.
Repeat
through
the
CT scans
scans
kidneys
should if the
be obtained findings
on initial
are equivocal.
U SUMMARY CT is now well established as an accurate noninvasive technique for the detection of the entire spectrum of renal injuries. In addilion, CT has proved to be superior to excretory urography and arteniography in defining
the extent of renal injury. Familiarity with the CT appearance of lesions from minor, intermediate, and severe renal trauma and with possible sis
pitfalls
and
these
proper
will
allow
treatment
confident of patients
diagno-
19#{149}Streak artifacts. CT scan shows apparent extravasation of contrast medium (arrows). Repeat CT scan taken 24 hours later showed no evidence of renal abnormalities. Figure
9.
Lang
with
injuries. 10.
U
REFERENCES 1 . Bretan PNJr,
2
3
.
.
5.
6.
.
ing of renal Urol 1986;
trauma: 85 consecutive 136:561-565.
8.
40
U
RadioGraphics
MP, Jef-
tomographic cases.
stagJ
Cass AS, Ireland GW. Comparison of the conservative and surgical management of the more severe degrees of renal trauma in multiple injured patients. J Urol 1973; i09:8-iO. Cass AS. Immediate radiologic and surgical management of renal injuries. J Trauma
1980;
i23:247-249.
Federle MP, KaiserJA, McAninch JW, Jeffrey RB, Mall JC. The role of computed tomography in renal trauma. Radiology i981; 141: 455-460. Guerriero WG, Devine CJ. Urologic injuries. Norwalk: Appleton-Century-Crofts, 1984.
U
Fanney
i i
et a!
.
Assessment
of renal
trauma
by dy-
i42:747-750. 12.
Sandier
CM,
Toombs
graphic evaluation Radiology 1981; i3.
Schaner
puted
EG,
15.
.
BalowJE,
and
129:83-88. Steinberg inch JW. appearance
blunt 524. Toombs
Computed
injuries.
DoppmanJL.
perirenal
hematoma.
DL, Jeffrey
RB, Federle
The
tomo-
renal
Com-
in the diagnosis
computerized
of renal
of subAJR
1977;
MP, McAn-
tomography
pedicle
1984; i32:1i63-1 164. Thompson IM, Latourette
Results
16.
BD.
of blunt 141:461-466.
tomography
capsular 14
22:36i-363.
Cass AS. Genitouninary trauma. Boston: Blackwell Scientific, 1988. Erturk E, SheinfeldJ, DiMarco PL, Cockett AT. Renal trauma: evaluation with computenized tomography.J Urol 1985; i33:946949. Evins SC, Thomason B, Rosenblaum R. Nonoperative management of severe renal lacerations.JUrol
7.
Federle
Computerized
1982; 4
McAninchJW,
frey RBJr.
EK.
namic computed tomography. RadioGraphics i983; 3:566-584. McAninchJW, Federle MP. Evaluation of renal injuries with computerized tomography. JUrol i982; 128:456-460. Rhyner P, Federle MP, Jeffrey RB. CT of trauma to the abnormal kidney. AJR 1984;
injury.
J Urol
H, Montie
JE, et al.
of nonoperative management of renal trauma. J Urol i977; 118:522BD,
Sandler CM. blunt trauma.
Lester
RG,
Ben-Menachem
Y,
Computed tomography in Radiol Clin North Am 1977;
19:17.
Volume
10
Number
1
4
. ,,
,,,
.
Javier Brian
Fanney,
MD
Casillas, J. Murphy,
MD MD
Computed
tomography
agnostic
study
pecially
in
common. CT
scans
(CT)
in patients
large
trauma
In our
3-year
for
centers
abdominal
identified:
renal
laceration,
complete
iion,
fractured
nal
capsule,
renal
to the
small
vein
kidney
injury,
of each
The
lesion
with
artery
renal
kidney.
large
CT
renal
lesions
without
thrombosis, findings
are 2,500 hemato-
junction and
disrupan
intact
avulsion,
and
di-
es-
over
subcapsular
ureteropelvic
shattered
abnormal
injuries
traumatic
and
initial
trauma,
encompasses
following
laceration,
kidney,
and management U
contusion,
renal
multiple-system which
the
as the
or suspected
where
trauma,
mas,
employed
known
experience,
were
trauma
is frequently
with
clinical
reand
features
are reviewed.
INTRODUCTION
Renal injuries are classified into three categories. Category 1 lesions are relatively minor and are treated conservatively. Category 2 lesions are more serious injuries for which the type of therapy used depends on the amount of nonviable tissue, cxtent of hemorrhage, and presence or absence of extravasated urine. Category 3 lesions
are
catastrophic
injuries
that
require
The proper method of detecting, been debated. Computed tomography the entire spectrum of renal injuries modalities.
CT provides
precise
urgent
surgery.
staging, and managing renal trauma has long (CT) is capable of demonstrating virtually and has clear advantages over other imaging
anatomic
detail
of renal
injuries
that
otherwise
may be understaged on the basis of excretory urographic or angiographic findings. In addition, CT effectively reveals predisposing renal abnormalities and provides valuable information about other intraabdominal structures. The appearance of various renal injuries on CT scans are illustrated, and the clinical parameters and therapeutic implications (1 1 6) are reviewed. -
Index
terms:
Kidney,
RadloGraphics I
From
1990;
the
Department
CT,
8 1. 1 2 1 1
©RSNA,
Hospital,
3800
injuries,
81.41
10:29-40 of Radiology,
Miami. From the 1988 RSNA nal revision received October versity
#{149} Kidney,
Reservoir
University
annual meeting. 20. Address Rd, NW,
of Miami
School
Received March reprint requests Washington,
of Medicine 23, 1989; to D.R.F.,
DC 200072
and Jackson
accepted Department
and
Memorial
Medical
Center,
revision requested April of Radiology, Georgetown
19; fi. Uni.
197.
1990
29
Figure 1. Renal contusion. (a) CT scan shows delayed excretion tamed i week later (not shown) was normal. (b) On the drawing in the renal pelvis indicates absence of excretion.
U CATEGORY 1 INJURIES Although renal injuries occur in 1 0% of patients who sustain blunt abdominal trauma, 75%-85% of these injuries are minor and are treated nonsungically. Category 1 lesions in-
dude mental capsular
contusions,
intrarenal
infarctions, hematomas.
and
small
hematomas, isolated
segsub-
#{149} Renal Contusion A renal contusion is diagnosed when there delayed excretion of contrast medium (Fig i). The proposed cause of the radiologic finding is delayed tubular transit time secondary to edema. The abnormality may be global on segmental. Renal function invariably returns to normal within i week without sequelae.
30
U
RadioGrapbics
U
Fanney
et a!
in the right kidney. Repeat scan obof this injury, absence of cross-hatching
#{149} Intrarenal An
intrarenal
as a focal
Hematoma hematoma
renal
lesion
appears that
on
does
not
CT
scans
enhance
after administration of contrast material (Fig 2a) . These lesions are poorly marginated and may extend to the renal capsule. On scans obtained without contrast material enhancement, the hematoma is seen as an area of high attenuation relative to that of the renal parenchyma (Fig 2b).
is
#{149} Segmental
Infarction
A traumatic segmental infarction may from occlusion of intrarenal (interlobar
result or
arcuate) or polar arterial branches. It may be distinguished from an intrarenal hematoma by its sharply marginated wedge-shaped appearance (Fig 3). The affected area will later be transformed into a deep scar as the infarcted tissue is resorbed.
Volume
10
Number
1
Figure 2. Intrarenal scan taken without
hematoma. (a) contrast medium
CT
shows a poorly defined high-attenuation region in the right kidney (arrow), a finding representing acute hemorrhage. (b) On CT scan obtained after contrast
medium administration, the hematoma low in attenuation relative to the enhanced renal parenchyma. (C) Drawing of intrarenal hematoma.
is
b. Figure in the
January
3. Segmental infarction. left kidney (arrow). (b)
1990
(a) CT scan shows Drawing of corresponding
a wedge-shaped injury.
area
of low
attenuation
Fanney
et a!
U
RadioGrapbics
U
31
Figure 4. Small row). (b) Drawing
#{149} Small
subcapsular
hematoma.
(a)
CT scan
Subcapsular
Hematoma
A subcapsular hematoma is diagnosed when hemorrhage is confined to the immediate cxtrarenal area by the renal capsule (Fig 4). The fluid collection may be lenticular, and its presence is delineated by flattening of the kidney and separation from Gerota fascia by fat. U
CATEGORY
demonstrates
small
2 INJURIES
Category II lesions represent an intermediate degree of renal trauma, which includes injuryto the collecting system. These lesions may be treated conservatively or surgically, depending on clinical status of the patient
U
RadioGrapbics
U
in the
left
kidney
(ar-
and nadiologic assessment. CT has greatly influenced the management of these lesions, since it can accurately depict the extent of injury.
#{149} Large
Subcapsular
Fanney
et a!
Hematoma
Large subcapsular hematomas usually have a lenticular shape (Fig 5). The attenuation of the hematomas on CT scans may range from high (acute hematoma) to low (chronic hematoma). Large subcapsular hematomas may result in rare complications, such as infection or hypertension secondary to parenchymal compression, the so-called Page kidney. Evacuation of the hematoma surgically or percutaneously is appropriate in these cases. #{149} Corticomedullary Corticomedullary renchymal tears with the collecting juries are usually less hemorrhage
32
hematoma
of the lesion.
Laceration lacerations are deep pathat do not communicate system (Fig 6). These intreated conservatively unis severe.
Volume
10
Number
1
a. Figure denting drainage.
b. 5.
Large subcapsular hematoma. the right renal parenchyma. This (b) Drawing of the injury.
a. Figure 6. Corticomedullary ated with an acute perirenal (b) Drawing of corresponding
January
1990
laceration. hematoma. injury.
(a) CT scan shows a large subacute subcapsular fluid collection became infected and required
b. (a) CT scan shows a corticomedullary After conservative treatment, the patient
hematoma percutaneous
laceration recovered
Fanney
et a!
in-
(arrow) associuneventfully.
U
RadioGrapbics
U
33
Figure sation
7. Complete renal laceration. of contrast medium (arrows).
(a)
(b)
CT scan
Drawing
Figure 8. Renal fracture. (a) CT scan shows well perfused. Surgical repair was performed.
#{149} Complete
Renal
shows
of renal
deep
Laceration
RadioGrapbics
U
Fanney
et a!
left
kidney
with
extrava-
The
fragments
remain
plications. The improved contrast resolution and tomographic nature of CT allow superior detection of urine extravasation.
#{149} Renal
Fracture
A renal fracture is seen on CT scans as a single transection of the kidney into two poles, accompanied by extravasation of urine (Fig 8). These fractures often occur along intenlobar divisions, resulting in preservation of arterial blood supply. Thus, successful reconstruction
U
in the
b. a fracture of the left kidney (arrows). (b) Drawing of renal fracture.
Complete renal laceration is a focal parenchymal injury that extends into the collecting system and results in extravasation of opacified and nonopacified urine (Fig 7). Communication between the collecting system and penirenal hematoma may result in urinary obstruction due to clot, a situation that can lead to deterioration and late corn-
34
laceration
laceration.
is possible
in many
cases.
Volume
10
Number
1
a. Figure
b.
Disruption of the ureteropelvic junction. (a) travasation of opacified urine. Renal parenchyma is intact. picts extravasation of urine from disrupted junction.
a. Figure heads) ment,
9.
10.
Shattered
with well-perfused the patient recovered
#{149} Disruption Junction Disruption occur
of of the
after
an
event
(Fig
9).
urine
without
proper
kidney
diagnosis.
with
contained
fragments (K) uneventfully.
fragments.
(a)
1990
b. CT scan
junction
may
Extravasation
of opacified
parenchymal
injury
is a clue
to
was
shows
#{149} Shattered
acceleration-deceleration
an enlarged
repair
right
kidney
performed.
multiple
(b)
with
Drawing
lacerations conservative
(C). After injury.
Kidney
with
cxde-
(arrowtreat-
Contained
Fragments A shattered kidney with contained fragments is demonstrated by CT as multiple lacerations of the renal parenchyma with an intact renal a special
treated
January
shows
Surgical
contained by the renal capsule (b) Drawing of corresponding
Ureteropelvic
ureteropelvic
CT scan
capsule
(Fig
category
i 0).
This
2 lesion,
injury which
represents may
be
nonsurgically.
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35
a. Figure 11. Renal vein thrombosis. (arrow) is present in the right renal bus in the renal vein.
b. (a) CT scan shows delayed excretion vein, extending to the inferior vena
a. Figure 12. Shattered kidney with disrupted capsule is torn, and blood (H) extends into (b) Drawing of the injury.
fragments. the
perirenal
(a)
in the right kidney. A thrombus cava. (b) Drawing depicts throm-
b. CT scan shows
space
(arrows)
#{149} Renal
Vein
. A
shattered left kidney (K) . The nephrectomy was performed.
Injury
Renal vein injury occurs in 20% of patients with solitary pedicle injury (Fig ii). These lesions have a better prognosis than arterial injuries. the renal traumatic managed
36
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Although laceration or avulsion vein requires immediate repair, renal vein thrombosis may be nonsurgically.
Volume
10
Number
of
1
Figure 13. Renal artery occlusion and thrombosis. (a) CT scan shows nonperfusion of the left kidney. The renal pedicle is seen (arrow). (b) Arteniogram definitively demonstrates the presence of a renal pedicle injury. (c) Drawing depicts the renal artery thrombus.
#{149} Renal Artery Occlusion Renal artery occlusion results from an acceleration-decelenation event, which causes intimal tear, subintimal dissection, and thrombosis (Fig 13). The ischemic kidney fails to opacify after administration of contrast medium. Collateral circulation may contribute to a “cortical rim” of enhancing parenchyma.
C.
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CATEGORY
Category
3 lesions
3 INJURIES constitute
5% of renal injuries and include renal pedicle injuries and shattered kidneys with disrupted fragments. These lesions require urgent surgery. Prompt diagnosis by means of CT allows successful reconstruction
in some
cases.
#{149} Shattered
Kidney
with
#{149} Renal Artery Avulsion Renal artery avulsion results from tearing of the musculanis and adventitia (Fig 14). CT is superior to arteniography, since it allows this more life-threatening injury to be distinguished from renal artery occlusion.
Disrupted
Fragments A shattered kidney with disrupted fragments results from violation of the renal capsule (Fig 12). Conservative therapy results in frequent short-term and long-term complications. Therefore, nephnectomy is the preferred treatment.
January
1990
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RadioGraphics
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37
a.
b. Figure 14. Renal artery avulsion. (a) CT scan shows nonperfusion of the right kidney with rim enhancement (white arrows). A large right penirenal hematoma and a small left perirenal hematoma (black arrow) are present. (b) Arteriogram shows interruption of the right renal artery. (C)
Drawing
of corresponding
injury.
C-
U ABNORMAL KIDNEY TRAUMA Preexisting congenital on acquired renal abnormalities are well known to predispose individuals to renal injury, even in the setting
of relatively minor trauma. Among these abnormalities are congenital anomalies such as horseshoe and pelvic kidney, hydronephrosis, tumors, and simple cysts. CT is extremely valuable in detection of the abnormality, which in turn may alter therapeutic management.
e 15. Ruptured angiomyolipoma. t. f scan demonstrates underlying renal mass with attenuation equal to that of fat (arrows). There is associated
hemorrhage.
For patient
example, not all renal hemorrhage who has sustained trauma may
solely cell
to
injury.
propensity trauma, surrounding
38
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Angiomyolipomas
carcinomas
are to
CT
vascular
hemorrhage.
revealed
and tumors In a case
extensive
a low-attenuation
Volume
in a be due renal
with
a
of minor
hemorrhage mass
10
(Fig
Number
15).
1
Figure
16.
Hemorrhagic
simple
shows high-attenuation ney. Note low-attenuation
fluid
cyst.
CT scan
within the right kidfluid in the periphery
Figure
18.
abdominal
(arrows).
U
.-.
Pseudosubcapsular
scan shows apparent tomas (arrowheads).
wall
PITFALLS
hematoma.
bilateral subcapsular Note duplication
musculature
CT
hemaof anterior
(arrows).
INTERPRETATION an important imaging IN
CT has become
modal-
in the evaluation of renal trauma. As a consequence, the radiologist must be familian with several misleading appearances in order to prevent erroneous diagnoses. Potential pitfalls include anatomic variations and various artifacts. ity
#{149} Renal
Pseudofracture
Renal pseudofracture is produced on CT scans by sectioning through the hilar lip of the kidney (Fig 1 7) . The characteristic location of the “fracture” and absence of penirenal fluid are clues to the correct diagnosis. Figure 17. cleft (arrow) right kidney.
A ruptured
Renal pseudofracture. in the posteromedial There is no perirenal
angiomyolipoma
CT scan shows aspect of the hematoma.
was found
at
surgery. CT is also valuable in distinguishing a ruptured or leaking simple cyst from hemorrhage. In one case, the CT scan showed both a high-attenuation fluid, representing marked hemorrhage into a renal cyst, and a low-attenuation fluid, representing leakage from the cyst (Fig 16). A renal cyst was discovered at surgery.
January
1990
#{149} Pseudosubcapsular
Hematoma
Pseudosubcapsular hematoma appears as apparent region of low attenuation along surface of the kidney (Fig 18). This artifact created by respiratory motion during data quisition. Recognition of a similar phenomenon in the anterior abdominal wall allows proper diagnosis. The artifact is confirmed when the low-attenuation area is not seen adjacent or repeat scans.
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an the is ac-
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39
#{149} Streak
Artifact
Streak artifacts from the urographic contrast medium may be misinterpreted as a collecting system injury (Fig 1 9). When these artifacts are associated with a penirenal hematoma, an erroneous diagnosis of a complete renal laceration may lead to unnecessary
surgery.
Repeat
through
the
CT scans
scans
kidneys
should if the
be obtained findings
on initial
are equivocal.
U SUMMARY CT is now well established as an accurate noninvasive technique for the detection of the entire spectrum of renal injuries. In addilion, CT has proved to be superior to excretory urography and arteniography in defining
the extent of renal injury. Familiarity with the CT appearance of lesions from minor, intermediate, and severe renal trauma and with possible sis
pitfalls
and
these
proper
will
allow
treatment
confident of patients
diagno-
19#{149}Streak artifacts. CT scan shows apparent extravasation of contrast medium (arrows). Repeat CT scan taken 24 hours later showed no evidence of renal abnormalities. Figure
9.
Lang
with
injuries. 10.
U
REFERENCES 1 . Bretan PNJr,
2
3
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.
5.
6.
.
ing of renal Urol 1986;
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8.
40
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RadioGraphics
MP, Jef-
tomographic cases.
stagJ
Cass AS, Ireland GW. Comparison of the conservative and surgical management of the more severe degrees of renal trauma in multiple injured patients. J Urol 1973; i09:8-iO. Cass AS. Immediate radiologic and surgical management of renal injuries. J Trauma
1980;
i23:247-249.
Federle MP, KaiserJA, McAninch JW, Jeffrey RB, Mall JC. The role of computed tomography in renal trauma. Radiology i981; 141: 455-460. Guerriero WG, Devine CJ. Urologic injuries. Norwalk: Appleton-Century-Crofts, 1984.
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Fanney
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Assessment
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trauma
by dy-
i42:747-750. 12.
Sandier
CM,
Toombs
graphic evaluation Radiology 1981; i3.
Schaner
puted
EG,
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BalowJE,
and
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Computed
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DoppmanJL.
perirenal
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DL, Jeffrey
RB, Federle
The
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Cass AS. Genitouninary trauma. Boston: Blackwell Scientific, 1988. Erturk E, SheinfeldJ, DiMarco PL, Cockett AT. Renal trauma: evaluation with computenized tomography.J Urol 1985; i33:946949. Evins SC, Thomason B, Rosenblaum R. Nonoperative management of severe renal lacerations.JUrol
7.
Federle
Computerized
1982; 4
McAninchJW,
frey RBJr.
EK.
namic computed tomography. RadioGraphics i983; 3:566-584. McAninchJW, Federle MP. Evaluation of renal injuries with computerized tomography. JUrol i982; 128:456-460. Rhyner P, Federle MP, Jeffrey RB. CT of trauma to the abnormal kidney. AJR 1984;
injury.
J Urol
H, Montie
JE, et al.
of nonoperative management of renal trauma. J Urol i977; 118:522BD,
Sandler CM. blunt trauma.
Lester
RG,
Ben-Menachem
Y,
Computed tomography in Radiol Clin North Am 1977;
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1
