For centuries, bowel trauma had a high mortality rate, and survivors escaped death by withstanding hemorrhage and sepsis. With the introduction of radiography, diagnostic accuracy improved. Multi-row helical detector CT scans are capable of scanning the abdomen in less than 30 seconds and can detect free air, free fluid, abnormal bowel wall enhancement, bowel wall thickening, and mesenteric infiltration. These advances in CT have brought the debate of conservative management of abdominal trauma full circle. Currently, many patients with blunt abdominal trauma or retroperitoneal penetrating trauma can be managed without surgery and can avoid unnecessary laparotomy.[1, 2, 3, 4, 5, 6, 7]
See the related images below.
View Image | A 47-year-old man with blunt trauma to the abdomen. Axial CT through upper abdomen reveals 2 spots of free intraperitoneal air (arrows). |
View Image | Female patient with right-sided colon perforation. Axial CT through the abdomen shows focal gas bubbles (red arrow) and anextraluminal fluid collectio.... |
Multidetector CT scanning using 16- and 64-slice CT has increased the speed in which trauma patients are scanned. In addition, 16- and 64-slice multidetector CT imaging allows the creation of isotropic voxels that allow reformats to be performed in sagittal and coronal planes, which can allow better localization of bowel injuries.
CT of the abdomen is the preferred diagnostic examination for the evaluation of blunt abdominal trauma in the hemodynamically stable patient with blunt abdominal trauma and in selected instances of penetrating trauma to the posterior abdomen. Unstable patients or patients with penetrating injuries to the abdomen undergo exploratory laparotomy.[8, 1, 2, 9, 10]
Abdominal CT examination should be systematic. Traumatic injury to the bowel is rarely isolated. First, evaluate the more commonly injured organs, such as the liver and spleen, as well as the pancreas, adrenals, kidneys, blood vessels, spine, and skeletal structures.
Evaluate traumatic injury to the bowel in the context of the mechanism and location of injury, as follows:
Each imaging modality (eg, plain abdominal radiograph, US, CT) demonstrates typical findings that suggest a diagnosis of bowel trauma.[11] In the hemodynamically stable patient with abdominal trauma, CT is the study of choice.
The accuracy of CT for the evaluation of bowel injury is as high as 97.6%.
CT can be limited if diagnostic peritoneal lavage (DPL) is performed prior to the CT. Free intraperitoneal fluid and air from the DPL observed on CT makes the evaluation for bowel injury very difficult.
Although CT can suggest bowel injury by demonstrating free intraperitoneal air, free fluid, or thickened bowel wall, in many instances it cannot reliably localize the exact location of bowel injury.
Delayed presentation of bowel injury occasionally occurs. Patients returning with continued symptoms several hours or days after a negative trauma should undergo repeat CT.[12]
Plain radiography findings in bowel injury include the following[13] :
Plain radiographs are not highly specific or sensitive for evaluating bowel injury. Findings of free air, abdominal fluid, scoliosis, and psoas shadow obliteration are observed in fewer than 43% of patients with intestinal trauma. Fluid collections must be large (>800 mL) to be visible on plain radiographs.
Pneumoperitoneum does not always indicate bowel rupture and can be observed in patients with pneumomediastinum or pneumothorax and in patients on mechanical ventilation.
CT is the modality of choice for evaluating abdominal trauma in the hemodynamically stable patient (see the images below).[14, 15, 16, 3, 17, 4, 18, 19, 20, 21, 22, 23] CT evaluation for blunt abdominal trauma can be difficult and requires strict attention to meticulous techniques.
View Image | A 47-year-old man with blunt trauma to the abdomen. Axial CT through upper abdomen reveals 2 spots of free intraperitoneal air (arrows). |
View Image | A 15-year-old boy with blunt trauma to the abdomen and a perforated stomach. Axial CT demonstrates large amount of free intraperitoneal air (green arr.... |
View Image | Patient in a motor vehicle collision with injury to the spleen. Axial CT through the abdomen shows thickening and enhancement of bowel wall in the lef.... |
View Image | A 47-year-old man with blunt trauma to the abdomen. Axial CT through the level of the pelvis shows small bowel wall thickening and enhancement (red ar.... |
View Image | A 19-year-old man with right-sided chest trauma. Axial CT through the upper abdomen shows a large amount of right retroperitoneal air surrounding the .... |
View Image | Patient with blunt abdominal trauma with duodenal hematoma. Axial CT through the abdomen shows soft tissue density and mild stranding surrounding duod.... |
View Image | Female patient with blunt abdominal trauma and duodenal perforation. Focal axial CT of the right upper abdomen shows free intraperitoneal air (red arr.... |
View Image | Female patient with right-sided colon perforation. Axial CT through the abdomen shows focal gas bubbles (red arrow) and anextraluminal fluid collectio.... |
View Image | A 79-year-old woman after a motor vehicle collision. Axial CT through the level of the pelvis shows a focal area of small bowel wall thickening (red a.... |
View Image | A 24-year-old man with blunt abdominal trauma and duodenal hematoma. Upper gastrointestinal series of the region of the duodenum shows large filling d.... |
Administer oral and intravenous contrast. Extend sections from the base of the lungs to below the symphysis pubis. View these sections in the "abdominal, lung, liver" and "bone" windows. Carefully search for associated injuries, including Chance or vertebral burst fractures; abdominal bruising; and pancreatic, liver, spleen, adrenal, and kidney injury. Consider administering rectal contrast in patients with suggested penetrating injury to the rectum or retroperitoneal colon.
Multidetector CT scanning using a 16- or 64-slice CT allows for coronal and sagittal reformats. Examination of these off-axis images allows for improved detection and localization of bowel injuries.[22, 5, 6, 7]
The coronal plane is especially helpful because it provides an anatomic view and helps referring physicians/surgeons better understand the location and extent of injury.
The sagittal plane is helpful in the evaluation of the thoracic and lumbar spine and can detect associated compression fractures of the spine, which may be missed when viewed in the axial plane alone.
CT findings in bowel injury include the following (also see Table 1, below):
Table 1. CT Findings in Bowel Injury
View Table | See Table |
The accuracy of CT for evaluating bowel injury is 82%, with a sensitivity of 64% and a specificity of 97%.
Some findings on CT suggesting bowel injury can represent false-positive findings, such as the following:
Typically, the role of US in evaluating bowel trauma is limited to detecting free intraperitoneal fluid in trauma patients who are not sufficiently hemodynamically stable to undergo CT. However, the identified fluid cannot be further defined. Considerations include benign ascites, blood, urine, or bile and must be confirmed with CT.[24, 11]
Other findings of bowel injury include dilated bowel loops secondary to an ileus or obstruction. US is insensitive in detecting intraperitoneal free air.
The only role of angiography in acute bowel trauma is to identify the site of visceral bleeding.[25]
A 15-year-old boy with blunt trauma to the abdomen and a perforated stomach. Axial CT demonstrates large amount of free intraperitoneal air (green arrow). An air/fluid level with fluid is seen in the right paracolic gutter (red arrow). Extravasated oral contrast is seen in the left paracolic gutter (blue arrow) adjacent to the stomach.
A 47-year-old man with blunt trauma to the abdomen. Axial CT through the level of the pelvis shows small bowel wall thickening and enhancement (red arrow) from blunt small bowel injury. Free intraperitoneal air visualized (blue arrow) is from a perforated sigmoid colon. Image from AJR 2000;174:1538 printed with permission from American Roentgen Ray Society.
A 19-year-old man with right-sided chest trauma. Axial CT through the upper abdomen shows a large amount of right retroperitoneal air surrounding the right kidney (arrows). Some air is seen in the right subcutaneous tissues. Retroperitoneal air dissected downwards from a right-sided chest pneumothorax.
A 24-year-old man with blunt abdominal trauma and duodenal hematoma. Upper gastrointestinal series of the region of the duodenum shows large filling defect (arrow) compressing the contrast-filled second portion of duodenum lumen. Findings are consistent with an intramural duodenal hematoma. No extravasation of contrast is observed that suggests duodenal perforation.
A 15-year-old boy with blunt trauma to the abdomen and a perforated stomach. Axial CT demonstrates large amount of free intraperitoneal air (green arrow). An air/fluid level with fluid is seen in the right paracolic gutter (red arrow). Extravasated oral contrast is seen in the left paracolic gutter (blue arrow) adjacent to the stomach.
A 47-year-old man with blunt trauma to the abdomen. Axial CT through the level of the pelvis shows small bowel wall thickening and enhancement (red arrow) from blunt small bowel injury. Free intraperitoneal air visualized (blue arrow) is from a perforated sigmoid colon. Image from AJR 2000;174:1538 printed with permission from American Roentgen Ray Society.
A 19-year-old man with right-sided chest trauma. Axial CT through the upper abdomen shows a large amount of right retroperitoneal air surrounding the right kidney (arrows). Some air is seen in the right subcutaneous tissues. Retroperitoneal air dissected downwards from a right-sided chest pneumothorax.
A 24-year-old man with blunt abdominal trauma and duodenal hematoma. Upper gastrointestinal series of the region of the duodenum shows large filling defect (arrow) compressing the contrast-filled second portion of duodenum lumen. Findings are consistent with an intramural duodenal hematoma. No extravasation of contrast is observed that suggests duodenal perforation.
Abdominal CT Direct Findings Indirect Findings Bowel injury Bowel wall disruption and oral contrast extravasation Free intraperitoneal/retroperitoneal air, free intraperitoneal/retroperitoneal fluid
Focal areas of bowel wall thickening, abnormal bowel wall enhancementMesenteric vascular injury Intravenous contrast extravasation from the area of the mesentery Diffuse bowel wall thickening, diffuse bowel wall enhancement, mesenteric infiltration/mesenteric hematoma