Prepared by Tad T. Renvyle, MD and Kimball G. Clark, MD of
the Department of Radiology, Upstate Medical University,
A 22-year-old man presented to the emergency department
complaining of abdominal pain after sustaining blunt trauma to his
abdomen in a motorcycle accident. Physical examination revealed an
epigastric abrasion, diffuse abdominal tenderness, and absent bowel
sounds. Laboratory test results showed an hemato-crit of 48 and a
white blood cell count of 21.8. A computed tomographic (CT) exam
was performed followed by gastrograffin enema. Twenty-four hours
later an upper gastrointestinal series was performed, followed by
Proximal jejunal transection
CT examination of the abdomen and pelvis with oral and
intravenous contrast demonstrated a left rectus sheath hematoma.
The subjacent small bowel showed wall thickening with intramural
low attenuation regions thought to represent hematoma (figure 1A).
A small amount of free fluid was present in the pelvis (figure 1B).
No free air was observed. Due to fat stranding of the left
lateroconal fascia adjacent to the descending colon (figure 1A), a
gastrograffin enema was performed to rule out colonic injury. No
colonic abnormality was seen, and the patient was admitted for
Due to continued patient complaints of abdominal pain and
vomiting, a gastrograffin upper gastrointestinal series was
performed. Initial images showed gastroesophageal reflux.
Subse-quent imaging showed contrast to flow promptly through a
dilated duodenum and come to an abrupt halt in the proximal jejunum
with a "beaked" appearance (figure 2). Scant amounts of contrast
extending from this "beak" were seen to outline a mass. A diagnosis
of traumatic obstruction was made.
The patient was taken to the operating room where a proximal
jejunal transection was found. The mass outlined by contrast was
omentum wrapped around and sealing off the transected jejunum.
Three liters of fluid were removed from the peritoneal cavity, the
injured bowel was resected, and a primary small bowel anastomosis
was performed. After a 1-week stay in the intensive care unit and
drainage of residual pelvic fluid collections, the patient
recovered well without complication.
Small bowel laceration/perforation occurs in 3% to 5% of cases
of blunt abdominal trauma.
The classic triad of small bowel injury (rigid abdomen, tenderness,
absent bowel sounds) occurs in only one-third of patients.
The detection of this subset of trauma patients has improved
markedly with CT, which has led to a decrease in the number of
negative laparotomies performed in the setting of blunt abdominal
In the setting of blunt abdominal trauma, CT has a sensitivity
of 92%, a specificity of 94%, a positive predictive accuracy of
30%, and a negative predictive accuracy of 100% for the diagnosis
of small-bowel laceration/contusion.
Common CT signs of small bowel perforation in order of decreasing
frequency include: peritoneal free fluid (80%), bowel wall
thickening (60%), free air (40%), and contrast extravasation (15%).
Hemoperitoneum can be diagnosed when the free fluid collections
measure >30 HU, with an average of 45 HU if <48 hours old.
Free air and contrast extravasation are found in only half of
patients with small-bowel perforation, but are each nearly 100%
specific for bowel perforation.
One other sign of small bowel rupture is the streaky mesentery
sign. In one series, this was found in 70% of patients with
small-bowel perforation on the mesenteric side.
Although no one sign is 100% sensitive, the presence of multiple
signs carry a 90% sensitivity and 95% specificity.
When small bowel, particularly duodenal, injury is present,
there is a high association of solid organ injury. These include
pancreas (45%), liver (30%), spleen (25%), and kidney (10%).
There is also a 15% incidence of colonic injury.
The presence of these other injuries may delay diagnosis of small
bowel injury; to avoid this a thorough examination of the small
bowel should be performed when these injuries are present.
Extraperitoneal injuries may also mask small bowel injury,
particularly retroperitoneal and rectus sheath hematomas, as in
If treatment of small bowel perforation is delayed, mortality rises
dramatically from 5% to 65%.
If abdominal complaints persist after an initial CT shows no
bowel injury, continued surveillance is warranted. A surgical
series from Canada has reported delayed intestinal perfor-ation
after blunt abdominal trauma.
All patients had persistent complaints of abdominal pain.
Three-quarters of the patients had spinal injury. All had either
direct insult to the bowel or the mesenteric vessels, with 75%
showing adjacent mesenteric hematoma.
Continued surveillance with CT is widely accepted.
The role of other contrast studies such as UGI series is not yet
Small bowel injury is an uncommon sequela of blunt abdominal
trauma, but a highly lethal injury if diagnosis is delayed. CT
examination in the acute setting of small bowel insult is both
sensitive and specific when certain signs such as free fluid and
free air are present. Other injuries commonly occur in conjunction
with small bowel injury, and when present should heighten the
radiologist's suspicion of small bowel injury. If there is
continued unexplained abdominal pain, follow-up CT scan of the
abdomen is warranted.