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Management Of Abdominal Gunshot Wounds

Firearms injuries to the abdomen can affect multiple organs and can even traverse the diaphragm and cause thoracic injuries. Abdominal gunshot wounds may be isolated, but as in over one-quarter of these patients, there may be more than 1 injury present.92 Hollow-organ injuries are the most common, with the small bowel being the most commonly injured organ. Solid-organ injuries and genitourinary injuries are less common but must be considered and evaluated. Historically, many of these wounds mandated emergent exploratory laparotomy, but recently, more-conservative management plans have also been shown to have success.92,93

There are 4 anatomic zones of the abdominal cavity, which can help suggest the type of injury potentially present.92 (See Table 9.) Regardless of the external site of injury and the initial tract of the projectile, injuries can occur in remote sites due to ricochet and cavitary effects of the projectile. Because of the many possible intra-abdominal injuries, management of patients with abdominal gunshot wounds is based initially on physical examination and hemodynamic findings. Clearly, the unstable patient, the patient with an eviscerating injury, or the patient with peritonitis on examination will likely require operative intervention,94-96 but many of these patients are initially hemodynamically stable or unable to be assessed because they are sedated and intubated. In these less clearcut cases, diagnostic studies must be performed to help identify which patients can be managed nonoperatively and which patients require urgent exploratory surgery.

Serial physical examinations and frequent vital sign re-evaluation are the most important diagnostic tests to perform, as the development of instability or peritonitis later in the course of the ED evaluation can direct an immediate need for surgical exploration. (See Table 10.) In patients who remain stable, laboratory and radiographic tests are required to determine a location of injury or the presence of intra-abdominal blood.

Typical laboratory studies that are obtained include complete blood count, blood gas, renal function, electrolytes, lactic acid, and urinalysis. A type and crossmatch for blood products may also be necessary, depending on the severity of the injury. Results of these laboratory studies alone are rarely indications to proceed to surgery, but significant base deficits, highly elevated lactate levels, and significant anemia may indicate the need for more aggressive or operative management.

Radiographic studies should always be obtained in the stable patient with an abdominal gunshot wound. The FAST scan is useful in the unstable patient to determine the presence of blood in the pericardium and/or peritoneum, but a negative study does not rule out intra-abdominal organ injuries, particularly hollow-organ injuries. A positive FAST scan in the stable trauma patient does not necessarily warrant emergent operative intervention, but it may help direct further testing and evaluation, as intraperitoneal fluid found on FAST without other ultrasound or clinical findings may suggest hollow viscus or diaphragmatic injuries.92

Plain film radiography of the chest, abdomen, and pelvis is typically employed to determine intrathoracic injuries, and it can help provide information regarding the location of the projectile as well as the number of missiles within the abdominal cavity. Both anteroposterior and lateral films must be obtained to determine whether the projectile is in the abdominal cavity. (See Figures 2 and 3.) If the number of superficial wounds does not match the number or projectiles present on plain films, further imaging or thorough operative exploration is required.

Computed tomography scans have become standard in the evaluation of the stable trauma patient with suspected intra-abdominal or pelvic injuries from gunshot wounds. Not only do CT scans assist in determining the location of penetrating injuries and the amount of blood present in the peritoneum, they also allow for evaluation of the missile path and help with decision-making for operative versus nonoperative management. Velmahos et al performed a prospective observational study of 100 patients with abdominal gunshot wounds who were hemodynamically stable and were initially planned to undergo nonoperative management.98 The investigators used CT scans with IV contrast only and found a 90.5% sensitivity and 96% specificity for determining the need for operative intervention. Twenty-six patients required exploratory laparotomy based on CT findings, and only 5 of these had a nontherapeutic laparotomy; none had postoperative complications. Two patients had missed injuries on CT but had clinical worsening and required surgical evaluation. Neither had a bad outcome because of the delay to surgery. Based on this study, many trauma centers have opted to drop oral and/or rectal contrast from their trauma CT protocols.

The availability and advances in CT and ultrasound have now largely relegated diagnostic peritoneal lavage (DPL) to an infrequently performed procedure in many facilities. Diagnostic peritoneal lavage is a highly sensitive, invasive test with a reported sensitivity of 96% for identifying intraperitoneal injuries caused by gunshot wounds,99 and it may still have utility in certain situations, particularly in unstable patients who cannot proceed to CT scanning. For example, in the patient who is intubated and cannot be clinically evaluated, a positive DPL can detect a possible hollow viscus injury. Likewise, in a patient with penetrating trauma to the lower thorax, flank, or back, a positive DPL can determine
if there is an intraperitoneal injury. A grossly positive DPL in the unstable patient indicates that intra-abdominal bleeding may be the source of hemodynamic instability. A positive DPL in penetrating trauma is classically 5000 to 10,000 red blood cells (RBCs)/mm3. A recent retrospective study by Thacker suggests the criteria for a positive test can be changed without missing clinically significant injuries. This study identified the following criteria as a positive DPL: 100,000 RBC/mm3 plus either > 500 white blood cells/mm3 or the presence of bile, or the presence of amylase in the peritoneal fluid.99

Interventional Radiology

In circumstances where a vascular injury or isolated pelvic vascular injury is the primary source of hemorrhage, interventional radiology may be the diagnostic and therapeutic modality of choice. Interventional radiology can be therapeutic if the vessel can be embolized to help control the bleeding.

Diagnostic Laparoscopy

Laparoscopy can also be performed as a diagnostic procedure to gain direct visualization of the source of intraperitoneal bleeding, possible bowel perforations, and diaphragmatic injuries before proceeding to an open exploratory laparotomy in select patients. Laparoscopy, however, is limited as a diagnostic test because it can miss posterior diaphragmatic injuries, retroperitoneal structure injuries, and subtle hollow viscus injuries.100

Treatment For Abdominal Gunshot Wounds

After thorough evaluation for other injuries requiring more emergent treatment, initial resuscitation of the abdominal gunshot wound victim begins with fluid resuscitation. Classically, crystalloid (lactated Ringer solution) is the initial resuscitative fluid used, but prompt use of blood products is the mainstay of appropriate fluid resuscitation. Recent literature suggests a low RBC:FFP ratio be instituted as soon as the need for blood products is determined. Likewise, hypotensive resuscitation is recommended while awaiting surgical intervention, when appropriate. With all ballistic trauma to the abdomen, immediate trauma surgery consultation or transfer is indicated. If the patient is not at a trauma center, stabilization with fluid and blood products is appropriate, but there should be no delay in transfer to a higher level of care. If the patient is unstable and requires transfer, CT imaging can be deferred, but all transfers should be discussed with the receiving surgeon.

Hemodynamically unstable patients or those with peritonitis after abdominal gunshot wound injuries should be appropriately resuscitated with fluid and blood products and referred for emergent exploratory laparotomy. Bleeding is controlled with pressure, when possible, and potentially unstable pelvic injuries are managed with compression of the pelvis with a pelvic binder or a tightly wrapped sheet. Patients with suspected pelvic bleeding may be selectively
managed with angiography as noted above if an exploratory laparotomy is not deemed necessary.

Hemodynamically stable patients without peritonitis can be managed with a more selective approach, as time may allow for CT imaging to assess for the location of injury and to determine if the injuries present warrant exploratory laparotomy. Head, C-spine, thoracic, and abdominal CT scanning (“pan scan”) is occasionally warranted in the multiply injured patient or those in whom a full clinical evaluation is not possible because of intubation, but many of these patients will require surgical exploration.

Selective Nonoperative Management For Abdominal Trauma

In recent years, more cases of penetrating abdominal trauma have been managed successfully without proceeding to exploratory laparotomy. This management strategy is the surgeon’s prerogative and is clearly not the emergency clinician’s decision to make. Velmahos et al retrospectively reviewed 792 patients who underwent selective nonoperative management at 1 institution and found that only 4% required delayed laparotomy after worsening clinical examination; none of the patients had a bad long-term outcome. They noted that nonoperative management is only appropriate at institutions where there is always an on-call surgeon available, rapid transfer to the operating room is feasible at all hours of the day, and there are providers available 24 hours a day for serial examinations to assess for acute worsening.101

 
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Last Modified: 07/19/2018
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