Dr. Mirvis is with the Department of Diagnostic Radiology,
University of Maryland Medical Center and Maryland Shock-Trauma
Center, Baltimore, MD. He is also a member of the Editorial
Board of this journal.
Recognition of the spleen's role in immunityparticularly for
phagocytosis of encapsulated bacteriaand the potential for rare,
but often fatal, overwhelming postsplenectomy sepsis has led to
greater efforts to conserve the spleen following injury.
The trend towards nonoperative treatment of splenic injuries was
first established in the pediatric population. The higher risk of
postsplenectomy sepsis coupled with a high rate of success with
nonoperative management (NOM) in the pediatric population fostered
this approach. In recent years, there has been growing interest in
NOM of splenic injury in the adult population.
Pachter et al
described the changing pattern in management of splenic rupture.
Over a 6-year period prior to 1990 only 13% of adult patients with
splenic injury were managed initially nonoperatively. In the next
6-year period, from 1990 to 1996, this number increased to 54%. The
authors noted in this comparison study that splenectomy was
associated with an excessive need for blood transfusion and a high
rate of postoperative sepsis. In the latter period, the success
rate for initial NOM was 98%.
Goan et al
described using NOM in 24 patients with severe liver and spleen
injuries and a moderate to large quantity of hemoperitoneum. Among
these patients, 18 had grade 3 or greater injuries on the American
Association for the Surgery of Trauma (AAST) Organ Injury Scale
They report a success rate of 84.6% and noted that the nonoperative
group had fewer transfusions, fewer complications, and shorter
hospital stays than patients undergoing early surgery. Two of the
24 patients failed NOM for spleen-related causes. They, as well as
Pachter et al,
noted that the absolute amount of hemoperitoneum was not a good
indicator of the likely outcome of NOM.
Criteria for nonoperative management
The criteria used to select patients for NOM of splenic injury
varies among institutions. A universal requirement is that the
patient is or becomes hemodynamically stable without requiring
on-going aggressive resuscitation. A variety of other clinical
factors have been considered in the decision to try NOM including
age, presence of abdominal pain, neurologic or mental status,
availability of intensive care unit monitoring, transfusion
requirements, quantity of hemoperitoneum, and extent of injury as
shown on CT scan. Smith et al
outlined specific clinical criteria for attempting nonoperative
treatment including: blood pressure >90 mmHg, pulse <110
after 2 liters of fluid, age >15 and <55 years, CT grade 1 to
3, lack of severe head injury, and a negative abdominal
examination. They reported only a 4% failure for NOM using these
criteria among patients in the study. Alternatively, Brasel et al
found that neither age nor neurologic status was a significant
factor in predicting the outcome of NOM of splenic injury. This
study described a growing incidence of NOM of splenic injury in
their institution and an 84% success rate among 116 patients
initially managed without surgery.
CT injury grading
Over the last decade, several attempts have been made to show
that the CT grade of injury could be used to predict outcome of NOM
(figures 1 through 4). A variety of CT grading systems have been
proposed and studied, but, in general, these have not shown enough
reliability in predicting outcome for a given patient. Mirvis et
in a study of 35 surgically treated patients, found that the
failure rate was greater among those with grade 1 or 2 injury than
for with grade 3 and 4 injuries as found on preoperative CT.
Similarly, Schurr et al
showed, using logistic regression, that CT injury grade had no
predictive value for outcome for a population of 89 patients
managed without surgery, 12 of whom ultimately required
Sutyak et al
concluded that CT scanning is inaccurate for estimating the extent
of splenic injury, often resulting in an underestimation of
severity. Further, they found a significant level of disagreement
between radiologists in establishing a CT-based injury grade. These
factors contribute to the poor correlation between CT appearance
and outcome in NOM of splenic injury. Similarly, Shapiro et al
showed that CT underestimated spleen injury in 36 patients at a
statistically significant level, with CT having an average injury
score of 3.2 versus a surgical injury score of 3.6 on an injury
scale of 5.
CT grading is also hampered by the fact that the CT shows only a
"single snapshot in time" of the injured spleen, but does not
document progression or healing without serial evaluations. One of
the greatest contributions of abdominal CT in the setting of spleen
injury is to exclude other intraperitoneal injuries that would
otherwise mandate surgical exploration.
CT appearance of arterial IV contrast
CT scanning with intravenous (IV) contrast enhancement can often
demonstrate direct evidence of vascular injury as shown by failure
of expected parenchymal enhancement (infarct) or by focal
extravascular contrast leak.
Faster scan times provided by helical or multirow detector scanning
and improved timing of peak arterial enhancement contribute to
improving sensitivity for recognition of direct vascular injury. A
contrast leak into the splenic parenchyma can occur into the
subcapsular, perisplenic, or intraperitoneal space. Typically these
appear as oval, rounded, or linear areas of focal high attenuation
similar to, or greater in density, than an adjacent artery or the
aorta. A contrast leak directly into the parenchyma, sometimes
referred to as a contrast "blush," will persist within the
parenchyma after arterial contrast wash-out occurs and is usually
surrounded by a nonenhancing hematoma from prior bleeding (figures
5 and 6).
A posttraumatic pseudoaneurysm results from an injury to the
arterial wall in which the adventitia and perivascular tissues form
a wall that focally contains the contrast (blood) leak. In this
case, the contrast density should decrease in the splenic
parenchyma as arterial enhancement levels diminish. The natural
progression of splenic pseudoaneurysm is not clearly known. Though
some splenic pseudoaneurysms heal by spontaneous thrombosis without
intervention, recent studies have shown that up to 67% of these
lesions may ultimately rupture and therefore represent a strong
predictor for failure of NOM in splenic injury.
In the arterial phase, in which abdominal CT is usually acquired
for trauma patients, parenchymal extravasation and pseudoaneurysm
have a similar appearance.
Traumatic arteriovenous fistula can result from trauma and also
appears as a focal hyperdense lesion similar to parenchymal
extravasation or pseudoaneurysm. Ongoing bleeding into the
subcapsular, or perisplenic intraperitoneal space typically appears
as a linear high-density region with a surrounding hematoma.
CT findings that can mimic splenic vascular lesions include
islands of enhanced splenic parenchyma surrounded by low
attenuation splenic laceration-contusions, and intact intrasplenic
vessels traversing the center or periphery of parenchymal
laceration(s) simulating hemorrhage surrounding a focal
pseudoaneurysm. Failure to detect splenic vascular lesions by CT
can be related to sub-optimal contrast enhancement, particularly in
obese patients with decreased tissue contrast resolution or delayed
scanning well beyond the peak of splenic-parenchymal enhancement
with "wash-out" of contrast occurring in pseudoaneurysms by
Understanding these potential diagnostic pitfalls, use of an
optimal volume and concentration of IV contrast material, scanning
at the peak of visceral contrast enhancement, and objective
contrast bolus timing techniques can improve detection of splenic
vascular injury. The absolute sensitivity (required rate of
bleeding or size of lesion) for detection of arterial bleeding by
technically optimized single-slice helical CT is, to the author's
knowledge, not known. Hypothetically, multirow detector CT imaging
systems with subsecond scanning performed with efficient contrast
bolus tracking should improve detection of these lesions.
Predictive value of CT contrast extravasation in blunt
Recently Schurr et al,
Davis et al,
and Sugg et al
have demonstrated the significance of a splenic "contrast blush" in
predicting failure of NOM. In the study by Schurr et al, 12 of 89
patients (13%) initially managed nonoperatively failed this
approach. A hyperdense collection was noted within the spleen
parenchyma on CT scan in 8 of these 12 (67%). Failure of NOM was
highly correlated with the CT contrast blush (P <0.0001). The
contrast blushes were demonstrated to be either contained
pseudoaneurysms of splenic vessels or foci of active bleeding
(figures 5 and 6). Davis et al then showed that angiography of
patients with a contrast blush on CT typically demonstrated
parenchymal pseudoaneurysms that could be successfully treated by
selective embolization. In this study, 26 of 322 patients (8%)
managed nonoperatively showed the CT contrast blush in the spleen,
with 20 patients having distal embolization of pseudoaneurysms
documented by angiography. Davis and colleagues also showed a
statistically significant improvement in outcome of NOM when
compared to NOM without angiographic evaluation.
In 1991, Sclafani et al
documented the value of proximal splenic artery embolization in
patients displaying angiographic abnormalities in improving splenic
salvage rate for NOM. Subsequently, he and his coworkers
described the use of proximal splenic artery embolization in 150
patients with blunt splenic injury undergoing NOM. In the later
report, 87 of 90 patients were managed successfully with bed rest
alone and an additional 60 underwent angiographic study and
proximal splenic artery embolization. The overall salvage rate in
blunt splenic trauma was 88%, including 22 patients managed
surgically. The overall success rate of NOM was 97% in patients
managed by either bed rest alone or angiography and embolization of
documented vascular injuries. The authors noted that CT grade did
not reliably predict outcome, with many patients with CT grades 3
and 4 injury treated successfully with NOM. In addition, they
suggested that enhanced abdominal CT could be used as a triage test
for splenic angiography.
A recent study at the University of Maryland Shock-Trauma Center
verifies that power-injected bolus enhanced spiral CT is a useful
study to determine the need for splenic angiography, based
primarily on the presence of a CT parenchymal "contrast blush." In
this study all patients with evidence of splenic injury on CT
underwent urgent splenic arteriography. Patients with angiograms
revealing contained parenchymal contrast extravasation or active
bleeding had selective embolization and distally in all but one
case (figures 5 and 6). There were two failures of embolization,
including the single patient who was embolized by proximal coils
only. The benefits of distal embolization included preservation of
splenic parenchyma with minimal chance of rebleeding due to
preserved collateral flow. The advantage of proximal embolization
is that it provides a quicker, technically easier procedure with
reduction of splenic arterial perfusion pressure with collateral
preservation of splenic immune function (RB Kranis MD, personal
communication, January 1999). Both proximal and distal embolization
can result in splenic infarctions of varying size, but are rarely
complicated by infection and/or abscess formation (K Killeen, MD,
personal communication, March 2000). The best technique of splenic
embolization is yet to be established.
Future studies will attempt to document more precisely the CT
findings that mandate angiographic assessment of the spleen for
potential embolization. The impact of combined spiral CT and
splenic arteriographic evaluation with embolization on splenic
preservation remains to be firmly established. It must be
emphasized that while NOM of splenic injury has achieved high
success rates in recent years, based on use of both clinical and
imaging parameters, the need for early, aggressive operative
intervention for splenic injuries associated with hemodynamic
compromise or other abdominal injuries requiring surgery must
The appropriate long-term clinical and imaging follow-up of
splenic injury managed nonoperatively has not yet been established.
Specifically, the value of obtaining a follow-up CT scan after
initial identification of splenic injury by CT is debatable.
Patients who develop hemodynamic instability or increasing
resuscitation requirements during attempted NOM either undergo
repeat CT or proceed directly to celiotomy. Lawson et al
found that routine follow-up CT scanning was not useful in 22
clinically stable patients with splenic injury managed
nonoperatively. Similarly, Thaemert et al
assessed the role of follow-up CT for nonoperatively managed
splenic injuries in 73 children and adults. Only 1 of 49 stable
patients undergoing follow-up CT had management altered due to the
CT result, with total CT procedure charges exceeding $54,000. On
the other hand, Federle
has pointed out that as many as 8% to 29% of blunt trauma patients
with splenic injury have delayed bleeding hours to weeks after
injury and follow-up CT might show early progression of injuries.
Also, he argues that follow-up CT can be very helpful in
demonstrating splenic healing as a prelude to resumption of full
physical activity. As noted by Federle, one criterion for return to
full physical activity (particularly contact sports) might be
demonstration of complete healing by repeat CT at 6 to12 weeks
described use of serial sonography to follow splenic injury to
document healing after initial CT diagnosis. He demonstrated a
correlation between injury grade by CT and time to complete
healing. At the Shock-Trauma Center at University of Maryland there
have been several instances in which repeat follow-up CT in
clinically stable patients revealed progression of splenic injury
or delayed appearance of pseudoaneurysms requiring splenic
angiography or surgical inspection of the spleen (figure 7).
In most cases, if there is no clinical evidence of injury
progression and no other injuries that require continued
hospitalization, most patients are discharged in 3 to 5 days. Some
physicians will obtain a repeat CT scan prior to discharge to
exclude any subclinical progression of injury, but this is by no
means universal. Also, some physicians may opt to perform a repeat
CT study prior to the patient resuming a physically demanding
activity to verify complete healing.
Songraphy for splenic injury
Krupnick et al
reported a 38% incidence of missed splenic injury and a 53%
incidence of injury downgrading in pediatric patients based on
sonography (radiologist/technologist performed) as compared with CT
for initial diagnosis. This finding argues strongly against the use
of sonography for initial the diagnosis of splenic injury. In
addition, 7 of 32 splenic injuries (22%) in this series had no
associated hemoperitoneum, raising questions about the role of
sonography in screening for abdominal injury based on the presence
or absence of free intraperitoneal fluid. AR
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