Intestinal Trauma

Etiology

Intestinal injury can result from either blunt or penetrating trauma. The majority of blunt abdominal trauma does not result in intestinal injury. Approximately three percent of blunt abdominal trauma results in intestinal injury, with the small bowel being the most common location. Penetrating traumatic injury is less frequent than blunt trauma; however, it more frequently results in intestinal injury. Penetrating trauma falls into two main categories: high-energy (projectiles) and low-energy (stabbings).

Epidemiology

Injury is one of the leading causes of death in people under the age of 44 years old. Like most traumatic injuries, the incidence is higher in males, with men accounting for approximately 80% of cases.[1] Intestinal injury is the third most common injury associated with blunt abdominal trauma, following spleen and liver.[2]

In penetrating injury, the small bowel is the most commonly injured, followed by the colon.[3] In stab wounds, intestinal injury varies from 30% to 83%, depending on the patient's body mass index (BMI). In patients with abdominal stab wounds, increased BMI is protective and is associated with a lower incidence of severe injury and need for operation.[4]

Pathophysiology

The pathophysiology of intestinal trauma is multifaceted including mechanical, ischemia/reperfusion, and signaling mediated mechanisms.

Mechanical injury can be direct or indirect. Penetrating trauma causes trauma to the intestines by direct laceration of the tissue from the penetrating object. The severity of injury depends on the penetrating object, its velocity, and the site and trajectory of the path. Penetrating trauma invariably also results in other associated injuries of the abdomen.

Blunt intestinal injury is usually caused by the intestine being crushed between external objects (e.g., car door, handlebars, etc.) and internal structures (e.g., vertebrae, pelvis, etc.). Indirect injuries in blunt trauma can also occur from acceleration/deceleration injuries when one part of the bowel is tethered in place and the other part is mobile. The duodenum-jejunum junction is a common site for this type of shear injury due to the stabilization of the duodenum by the ligament of Treitz. In patients with prior abdominal surgery, acceleration/deceleration injuries can be precipitated by underlying adhesions leading to an unpredictable pattern of traction injuries. Blunt injury can ultimately lead to devascularization of the affected segment of bowel, leading to intestinal necrosis.

Another mechanism for indirect intestinal injury involves a low perfusion state and global hypotension from hemorrhagic shock or direct vascular trauma. de Haan et al. found elevated circulating intestinal fatty acid binding protein (I-FABP) released as a result of intestinal injury in trauma patients which correlated well with triage scoring systems for trauma including the shock index, Abbreviated Injury Score (AIS), as well as the overall Injury Severity Score (ISS).

Acute phase reactants activated as a result of bowel injury leads to an increase in the permeability of the capillaries.[5] Additionally, high-volume crystalloid resuscitation classically administered to trauma patients results in decreased oncotic pressure and increased hydrostatic pressure that causes further extravasation of fluid and bowel edema.[5] Thus, guidelines recommend the early use of red blood cells, plasma, and platelets in an equal ratio in part to limit the extensive fluid shifts that occur with large volume crystalloid resuscitation.[6]

History and Physical

All trauma patients should be evaluated in a standard format beginning with the primary survey.[7] Following the primary survey, the team should search for other signs of injury during the secondary survey, while utilizing adjuncts as clinically indicated. During the secondary survey, the patient’s abdomen is assessed for visual signs of trauma and the presence of pain in a neurologically intact patient. In blunt abdominal trauma, the presence of a seatbelt sign was associated with a 4.7-fold increase of relative risk for small bowel perforation.[8] In penetrating trauma, the number and location of wounds help determine possible penetration and injuries.

Concurrent with the physical exam, clinicians should monitor vital signs and gather information regarding the mechanism. Understanding the mechanism of injury can provide important information about what type of injury the patient sustained. Additionally, if time allows and the patient is lucid, information regarding medical, surgical, social, allergy and family history should be obtained.

Evaluation

In addition to the initial history and physical exam, chest and pelvis radiographs, focused assessment of ultrasonography in trauma (FAST), diagnostic peritoneal lavage (DPL), computed tomography (CT) and diagnostic laparoscopy (DL) can be used to provide further information.

Radiographs- Typically a chest and pelvis radiograph are obtained to evaluate for the presence of an abnormal mediastinal profile, hemothorax or pneumothorax, air under or abnormality of the diaphragm, and fractures, particularly unstable pelvic fractures. Air under the diaphragm indicates intestinal perforation. Radiographs are also useful in penetrating injuries to evaluate for the type of foreign body and the trajectory of the foreign body.

Focused assessment of ultrasonography in trauma (FAST)- Fluid in the hepatorenal space, in the splenorenal space, and/or on the suprapubic view indicates there may be intraabdominal bleeding or intestinal injury. Although the FAST examination is a helpful adjunct, it has poor sensitivity for bowel injury. 

Diagnostic peritoneal lavage (DPL)- DPL can be a useful tool in determining which patients would benefit from an exploratory laparotomy. If less than ten milliliters of blood are obtained upon initial aspiration, then one liter of warm saline is poured into the abdomen. If the return of fluids shows RBC > 100,000 per cubic millimeter, WBC > 100 per cubic millimeter, food, or bile, then the patient should undergo exploratory laparotomy.[9]

Computed tomography (CT) scan- CT scanning is the most sensitive and specific imaging modality for intestinal trauma.[8] The overall sensitivity and specificity of CT for bowel/mesenteric injury were 88.3% and 99.4% respectively. Despite CT scanning being the gold standard, there is still a 15% false-negative rate for intestinal injury in patients experiencing blunt abdominal trauma.[8] Patients with an intestinal injury can present with free fluid, mesenteric hematomas, pneumoperitoneum, extravasated extraluminal oral contrast, and frank discontinuity of the vessel wall. Wall thickening and edema can occur as a result of blunt injury or as a sequela of global hypoperfusion to the small bowel. Penetrating injuries present with foreign bodies with injury along the path of their trajectory. This is usually associated with injuries of the abdominal viscera and surrounding bony structures. Intravenous contrast is beneficial in assessing patients with abdominal trauma.

Diagnostic laparoscopy (DL) – DL may help avoid a laparotomy in hemodynamically stable patients with penetrating abdominal trauma.[6] Indications for DL include the evaluation for peritoneal penetration in tangential penetrating wounds as well as suspected diaphragmatic and intestinal injuries in thoracoabdominal trauma. The reported accuracy was 98.66% with 97.61% sensitivity and 100% specificity.[6]

Treatment / Management

Treatment of intestinal trauma depends on the stability of the patient.

Stable Blunt Injury

Patients who have experienced blunt abdominal trauma, but remain stable should be managed in two main categories: Those with a reliable physical exam and those without. Factors that prevent a reliable clinical exam include brain injury, spinal cord trauma, intoxication, sedation, altered mental status, and distracting injuries. If none of these factors are present, guidelines do not require any further imaging, and the patient can be admitted for serial abdominal exams over the next 24 hours.

If the patient does not have a reliable physical exam, they should undergo CT scanning. If imaging is negative, these patients should still be admitted for 24 hours of serial abdominal examinations.[10](A1)

If an intestinal injury is identified via the CT scan, the patient should be taken to the operating room for exploratory laparotomy.

Stable Penetrating Injury

Patients who remain hemodynamically stable and have reliable physical exams (exclusion criteria mentioned above) may be managed non-operatively. EAST (Eastern Association for the Surgery of Trauma) guidelines recommend further workup or exploratory laparotomy if any of these factors are present. If none of the exclusion criteria are present, then serial abdominal exams are a reliable form of monitoring and should be continued for 24 hours.

If a patient is going to be treated initially with non-operative management, CT scanning is recommended regardless of the reliability of the physical exam. It has been shown to have a sensitivity of 90.5% and a specificity of 96.5% in penetrating abdominal trauma.[11]

The push to manage more penetrating abdominal injuries conservatively stems from the high rate of nontherapeutic laparotomies, and the associated morbidity, following penetrating abdominal injuries.[12](B2)

In the setting of penetrating abdominal injury, diagnostic laparoscopy is another potential option that can spare patients a laparotomy in the correct situation. Its most agreed upon use is for the diagnosis and repair of occult diaphragmatic injuries after penetrating injuries to the left upper quadrant. For diagnosing intestinal injury, it has proved less useful as studies have still shown a high rate of nontherapeutic laparotomies that were undertaken after diagnostic laparoscopy showed peritoneal penetration.[13](A1)

Unstable Blunt Injury

Unstable patients who have experienced blunt abdominal trauma should undergo DPL or FAST examination. If either is positive, then the patient should be taken for exploratory laparotomy. If both are negative or non-diagnostic, then further workup should be completed. Further workup consists of CT imaging and evaluation for other injuries that could be causing the shock.

Unstable Penetrating Injury

Unstable patients suspected of having a gastrointestinal injury should be taken to the operating room immediately for exploratory laparotomy.

Operative Management

Antibiotics should be given perioperatively. The antibiotic regimen should be as specific as possible, but due to the nature of trauma, the exact injury may be unknown, in which case broad-spectrum antibiotics would be appropriate. Current EAST (Eastern Association for the Surgery of Trauma) guidelines have a level I recommendation for only 24 hours of prophylactic antibiotics after the repair of intestinal trauma.[14] If an intraabdominal infection has already set in due to delayed presentation, the current guidelines recommend four days of antibiotics following source control.[15]

The exploratory laparotomy should be conducted in a systematic approach. There are four stages of a trauma laparotomy: 1) Control of hemorrhage, 2) Control of contamination, 3) Diagnosis of all injuries, and 4) Reconstruction.

Once hemostasis is achieved, intestinal injuries are evaluated systematically. The small bowel is run from the Ligament of Treitz to the cecum. Gastrointestinal spillage is controlled with atraumatic clamps (Babcock) or a running stitch. Next, the colon and intraperitoneal rectum are inspected. Stomach mobilization is essential for the detection of injuries. The lesser sac is opened to examine the anterior and posterior walls of the stomach and to visualize the duodenum. If there is a concern for duodenal injury, then the duodenum should be mobilized from its retroperitoneal attachments.

Definitive repair should be deferred until the entire bowel is evaluated. The specific approach taken depends on the extent of the injury, the injury location, the other concurrent injuries, and the patient’s clinical status. Options include primary repair, resection with primary anastomosis, resection with diversion, and resection with delayed abdominal closure as part of a damage control approach.

Primary repair- Partial-thickness injuries, or full-thickness injuries that that are less than three centimeters (cm) in the stomach, or less than 50% of the luminal circumference in the small bowel or colon can be repaired primarily. The primary repair could be accomplished with one or two layers of closure.

Resection and anastomosis- Multiple injuries within the same vicinity or a single injury greater than three cm in the stomach or greater than 50% of luminal circumference in the intestines should be resected with anastomosis as appropriate. The anastomosis can be completed with a stapler or in a hand-sewn approach, with studies showing similar efficacy. If there is significant bowel wall edema, differences in the luminal diameters, or the location of the injury is in a difficult anatomic location (near the ligament of Treitz), then a hand-sewn approach should be considered.[16](B2)

Diversion- A recent EAST systematic review found that primary repair or resection and anastomosis of bowel injuries were safe. Therefore, their published guideline recommended against diversion in low-risk patients. Even in high-risk patients, which they defined as delay greater than 12 hours, transfusion of more than six units of blood, contamination, and left-sided injuries, they recommended against mandatory colostomy. In high-risk situations, a surgeon can choose between repair and anastomosis, diversion, or damage control approach with an anastomosis after resuscitation and stabilization.[17] If bowel continuity cannot be established within 36 hours, then diversion is generally recommended to avoid an increased risk of anastomotic failure related to bowel edema.[18](A1)

Damage control approach – Damage control approach in intestinal injury from trauma attempts to obtain source control and then defer the definitive repair until after the patient has been appropriately resuscitated and stabilized. The EAST Clinical Management Update in 2010 did not have any level I recommendations for damage control approach in trauma.[19] (20539186). However, they did make a level III recommendation that a damage control approach could be considered in the setting of acidosis, hypothermia, coagulopathy, and massive transfusion (20539186). The definitive repair should then occur after these factors have been corrected, ideally within 36 hours. The concept of leaving the bowel in discontinuity is not universally accepted. A World Journal of Surgery study in 2017 showed increased intestinal ischemia when the bowels were left in discontinuity compared to definitive repair in the damage control setting.[20] The American Association for the Surgery of Trauma is currently conducting a multicenter prospective study examining this issue, which will hopefully provide more evidence regarding the correct management. 

Special Considerations

Duodenum- Due to the complexity of the surrounding anatomy, duodenal injury management requires special consideration. As mentioned above, the opening of the lesser sac is a standard part of a trauma laparotomy. If there is a concern for duodenal injury, then a Kocher maneuver should be performed. A right medial visceral rotation (Cattell-Braasch) can be performed for better exposure, and mobilization of the ligament of Treitz can be completed to access the fourth portion of the duodenum. Once exposure has been obtained, then attention can be turned to repair.

Isolated duodenal hematomas should not be explored. These can be treated with nasogastric decompression of the stomach until the obstructive symptoms resolve. Failure to resolve in approximately 2 weeks should lead to operative exploration and repair.

If the duodenal injury does not involve the second portion of the duodenum (the ampullary portion), then the injury can be repaired primarily if the involved portion is less than three cm or repaired via resection and anastomosis if greater than three centimeters. If a repair cannot be completed without tension, then duodenojejunostomy with Roux-en-Y reconstruction should be completed.[21]

If there is a concomitant pancreatic injury with the involvement of the second portion of the duodenum, then the area should be widely drained with definitive reconstruction planned for a later date.[21] If only the distal pancreatic duct is injured then distal pancreatectomy can be performed.

Extraperitoneal rectum- While intraperitoneal rectal injuries should be managed similarly to other colon injuries, extraperitoneal rectal injuries fall into a separate class. Current EAST guidelines for these injuries recommend proximal diversion for extraperitoneal rectal injuries if less than 25% of the rectum has been involved. This can be done without the need for presacral drainage or distal rectal washout.[22] However, others have argued that if the injury is accessible transanally, then it is reasonable to repair it primarily without diversion.[23] This same paper argued that if diversion is performed, then it is reasonable to consider reversal after a short course (approximately 10 days) if a contrast enema does not show any abnormality.[23] If the injury involves greater than 25% of the circumference of the rectum, then diversion is recommended.[23]

Differential Diagnosis

Hollow Viscus Injury

• Esophagus
• Stomach
• Small bowel
• Colon
• Rectum

Intrabdominal Vascular Injury

• Acute blood loss anemia

Bowel Ischemia

Mesenteric Hematoma

Bowel Wall Hematoma

Solid-organ Injury

• Liver injury
• Spleen injury
• Bladder injury

Retroperitoneal Injury

• Retroperitoneal hematoma
• Pancreas injury
• Kidney injury

Prognosis

The prognosis of the patient depends significantly on the condition of the patient and the injury sustained. Patients who choose not to undergo intervention due to age or other factors have a worse prognosis.[24] Patients who are poor surgical candidates but require a life-saving operation have a worse prognosis than their counterparts with fewer comorbidities.[1]

The overall mortality rate for traumatic intestinal injury ranges between 8% and 87%, with averages listed at approximately 25%.[1][25] The higher mortality rates were significantly related to hemodynamic instability.[25]

Complications

Missed Injury

Although missed intestinal injury has not been examined individually, multiple studies have examined outcomes in missed abdominal injuries after trauma. Prompt diagnosis is crucial because delay in treatment of 60 to 90 minutes was associated with increased mortality.[1]

Delayed Presentation

Delayed presentation is an inevitable result of more patient’s being managed non-operatively. In these cases, patients do not initially have any signs or symptoms of intestinal trauma. The patient’s other traumatic injuries are managed non-operatively, and then later, they develop symptoms leading to the discovery that there had been an intestinal injury. The safety regarding the increased use of non-operative management remains controversial.[26][27]

Bleeding

Bleeding associated with intestinal trauma complicates a surgeon’s ability to restore intestinal continuity properly. Higher blood product requirements are associated with higher anastomotic leaks.[28] Due to this fact, patients who are unstable and requiring blood products may require diversion or be left in discontinuity to allow for a more definitive repair once they are stabilized. Signs of bleeding include CT findings of extravasation of contrast and mesenteric hematoma.[29] Operatively, concern for bleeding should lead to thorough mobilization and inspection in intraabdominal and retroperitoneal structures. If the source is visualized, it can be repaired or ligated. If no discrete source is seen, then packing should be attempted. 

Leak After Repair

The leak of intestinal content following repair can lead to significant mortality. The intestinal leak rate after an intestinal repair is approximately 5% to 8%.[28][30] The increased leak rate was found to be associated with increasing Injury Severity Score, higher intraoperative fluid requirements, and higher intraoperative blood product administration.[19] No difference in leak rate was found between patients who were repaired with a hand-sewn anastomosis versus stapled anastomosis.