Bowel Injury following blunt abdominal trauma

A 3-year-old girl presented to the emergency room complaining of lower abdominal pain following a fall from height. On clinical examination, she was found to have abdominal distension. However, she had no hypotension or tachycardia.

Radiograph of the abdomen was performed as part of the emergency department protocol to assess for signs of acute surgical abdomen such as pneumoperitoneum or obstruction. It revealed dilated bowel loops with multiple air-fluid levels. On ultrasonography of the abdomen on portable machine in the emergency room, as per e-FAST (Extended Focused Assessment with Sonography in Trauma), few dilated bowel loops along with minimal free fluid in the right iliac fossa was noted. Part of the central abdomen was obscured due to bowel gas shadows.

As the patient was hemodynamically stable, further evaluation with contrast-enhanced computed tomography (CT) of the abdomen and pelvis with oral and intravenous contrast was decided as the finding of bowel dilatation was concerning. It revealed circumferential homogeneous enhancing wall thickening involving the distal ileal loops in the right iliac fossa and dilated jejunal and ileal loops with air-fluid levels, proximal to this point.

A ileal loop just before the transition point in the right iliac fossa showed lack of any mural enhancement along its mesenteric side with haziness of the adjacent mesentery.

Ill-defined interbowel free fluid was seen in the right iliac fossa, along with enhancement of the peritoneal lining along the right paracolic gutter in its inferior part. 

Rest of the abdominal viscera appeared normal.

Background

While the optimal strategy for imaging in children with blunt abdominal trauma is still under research, e-FAST remains a valuable screening method with very high sensitivity for detection of free fluid. [1] However, literature shows differential sensitivity of FAST to detect free fluid, particularly in children. [2] Abdominal CT scan is a reliable tool and can be utilised in the evaluation of hemodynamically stable patients presenting with signs and symptoms of blunt abdominal trauma with due consideration for risk of radiation exposure. [3] With a shift to nonoperative management in many cases, accurate and timely imaging is necessary for making the decision of conservative versus surgical management. Bowel and mesenteric injuries are detected in 5% of blunt abdominal trauma patients at laparotomy, with the most common sites of bowel injury being proximal jejunum, near the ligament of Treitz, and the distal ileum, near the ileocecal valve. In these regions, mobile and fixed portions of the gut are continuous and therefore are susceptible to shearing force. [4]

Multidetector CT is more sensitive and specific than diagnostic peritoneal lavage, abdominal ultrasonography (US), and clinical examination for the diagnosis of bowel and mesenteric injuries. The accuracy of CT for evaluating bowel injury is 82%, with a sensitivity of 64% and a specificity of 97%. [5]

Imaging Perspective

The direct signs of bowel injury include bowel wall disruption and extraluminal leakage of oral contrast, which are less frequently seen. Indirect signs include presence of intraperitoneal/retroperitoneal free fluid and/or gas, focal bowel wall thickening and absent or reduced bowel wall enhancement. Free fluid and/or gas may be seen in case of injury to other viscera as well, such as liver, spleen, bladder as well and a careful assessment of the other abdominal organs must be done in order to rule out other associated injuries in this setting. 

Impact of Imaging on Treatment Plan

According to the World Society of Emergency Surgery (WSES) guidelines on bowel trauma diagnosis and management, presence of highly specific CT findings such as extraluminal gas, extraluminal oral contrast, or bowel-wall defects warrants prompt surgical exploration. The combination of the FAST assessment and abdominal computed tomography in selected patients improves the detection of clinically inapparent bowel injuries avoiding complications and potentially like-threatening implications. [2] In our case, the presence of free fluid on FAST along with the radiographic findings concerning bowel obstruction, a CT scan was performed in order to better delineate any point of transition and plan further management. In patients who demonstrate evolving clinical signs suspicious of bowel injury, CT scan should definitely be considered if not performed during initial assessment. [6]

Teaching Point

The illustrated case showed a focal area of mesenteric stranding that drew our attention to the adjacent bowel wall thickening with absent enhancement along its mesenteric aspect, indicating bowel injury. It highlights the importance of careful examination of bowel segments, mesentery and peritoneum in such cases as the management would change drastically in the absence of these findings. Our patient underwent exploratory laparotomy in view of radiological and clinical suspicion of bowel injury, with intraoperative finding of focal segment of bowel wall ischemia in the ileal loops with mesenteric contusion. Resection and anastomosis of the involved bowel loop was performed.  

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