Penetrating Abdominal Trauma

Etiology

Penetrating trauma occurs when a foreign object pierces the skin and enters the body creating a wound. In blunt or non-penetrating trauma the skin is not necessarily broken. In penetrating trauma, the object remains in the tissue or passes through the tissues and exits the body. An injury in which an object enters the body and passes through is called a perforating injury. Perforating trauma is associated with an entrance wound and an exit wound.[1]

Penetrating trauma suggests the object does not pass through. Penetrating trauma can be caused by violence and may result from:

• Fragments of a broken bone
• Gunshots
• Knife wounds

Penetrating trauma often causes damage to internal organs resulting in shock and infection. The severity depends on the body organs involved, the characteristics of the object, and the amount of energy transmitted. Assessment includes x-rays, CT scans, and MRI. Treatment involves surgery to repair damaged structures and remove foreign objects.

Puncture and penetration are similar.

• A puncture does not have an exit wound. It is generally due to something sharp or pointed
• This type of trauma is seen in a stabbing or when stepping on a nail.

Epidemiology

United States

Suicide and homicide are consistently high causes of death. Approximately 40% of homicides and 16% of suicides by firearm involved injuries to the torso.[2][3]

• Traumatic injury is the third leading cause of death and number one in persons aged 1 to 44 years.
• Penetrating abdominal trauma affects 35% of those patients admitted to urban trauma centers and up to 12% of those admitted in suburban or rural centers.

International

The frequency of penetrating abdominal injury increases when weapons are available, and also increases in the presence of military conflicts. Therefore, the frequency varies.

Racial

Age-adjusted firearm death rates are two to seven times higher for non-Hispanic black males.

Sex

Approximately 90% of patients with penetrating trauma are male.

Pathophysiology

As a projectile passes through tissue, it decelerates and transfers kinetic energy to the tissue. Increased velocity causes more damage than mass. Kinetic energy increases with the square of the velocity.

The space left by tissue that is destroyed by the penetrating object forms a cavity, and this is called permanent cavitation. In addition to the damage to the tissues they contact, medium- and high-velocity projectiles result in a secondary cavitation injury as the object enters the body, it creates a pressure wave forcing tissue out of the way, creating a cavity. The tissues move back into place, eliminating the cavity, but the cavitation has already done considerable damage.

The characteristics of the damaged tissue determine the severity of the injury: the denser the tissue, the greater the amount of energy transmitted to it.

History and Physical

Penetrating abdominal trauma is due to stabbings, ballistic injuries, and industrial accidents. These injuries may be life-threatening because abdominal organs bleed profusely. If the pancreas is injured, further injury occurs from autodigestion. Injuries of the liver often present in shock because the liver tissue has a large blood supply. The intestines are at risk of perforation with concomitant fecal matter complicating penetration.

Penetrating abdominal trauma may cause hypovolemic shock and peritonitis. Penetration may diminish bowel sounds due to bleeding, infection, and irritation, and injuries to arteries may cause bruits. Percussion reveals hyperresonance or dullness suggesting blood. The abdomen may be distended or tender indicating surgery is needed.

The standard management of penetrating abdominal trauma is a laparotomy. A greater understanding of mechanisms of injury and improved imaging has resulted in conservative operative strategies in some cases.

Evaluation

Gross assessment may be difficult as damage is often internal. The patient should be examined physically followed by ultrasound, x-ray, and/or CT scanning. Sometimes before an x-ray is performed a paper clip is taped over entry and exit wounds. [4][5][6]

The patient is treated with intravenous fluids and/or blood. Surgery is often required; impaled objects are secured in place so that they do not move and they should only be removed in an operating room.

Foreign bodies such as bullets may be removed, but if there is a possibility that they may cause more damage, they should be left in place. Wounds are debrided to remove tissue that cannot survive and will lead to infection.

Treatment / Management

The presentation of a patient with penetrating abdominal injury may reveal shock, hypotension, narrow pulse pressure, tachypnea, oliguria, and an apparent trajectory or open wound. Examination in awake patients may reveal signs of peritonitis such as guarding or rebound tenderness. The approach to patients with penetrating abdominal trauma depends on the type of instrument that caused the injury and hemodynamic status. In general, gunshots to the abdomen are usually associated with hollow viscus injury and usually require exploration. Knife wounds are associated with a lower incidence of intra-abdominal injury, and hence, their work-up requires clinical judgment and experience. Many protocols exist for evaluating patients with a stab wound to the abdomen. Blood work is always done but is nonspecific. The use of DPL and FAST can be performed to assess the stable patient with a knife or gunshot wound, but both these modalities have a high rate of false negatives. CT scan is used in patients with wounds of the flank and back and can help assess solid organ injury. The diagnostic test of choice is a triple contrast CT scan in hemodynamically stable patients. Other imaging tests may be done to assess for any associated head or skeletal injury. In most hospitals, penetrating trauma is handled by a trauma team. After the ABCs are completed, most gunshot patients require an exploratory laparotomy. This view is now changing, and stable patients with gunshot wounds with no signs of peritonitis who have been evaluated by a triple contrast CT scan may be observed if there is no evidence of intra-abdominal injury. The indications for surgical intervention include (1) patient with hemodynamic instability, (2) development of peritoneal findings such as involuntary guarding, point tenderness or rebound tenderness, and (3) diffuse abdominal pain that does not resolve.[7][8][9]

Patients with a stab wound with clear signs of peritonitis similarly require a laparotomy. Stable patients with stab wounds may be locally explored or undergo a triple contrast CT scan. The principles of surgery include (1) management of bleeding, (2) quick identification of any serious injury, (3) rapid control of contamination, and (4) reconstruction when possible. If there is an associated vascular injury, a consult with a vascular surgeon is highly recommended.

The prognosis of patients with penetrating abdominal trauma is variable and depends on the extent of injury and time of presentation to the emergency department. In the presence of massive abdominal contamination from a perforated viscus, hemorrhage, multiorgan injury, associated head injury, or coagulopathy, the mortality rates are high. In patients who are promptly resuscitated and explored, the mortality rates remain low. Stab wounds to the abdomen usually have a much better prognosis than gunshot wounds.

Depending on the injury, these patients often need some rehabilitation to get them back to their original level of function.[10][11](A1)

Differential Diagnosis

• Abdominal compartment syndrome
• Hemorrhagic shock
• Trauma to pelvis, diaphragm, or genitourinary system
• Sepsis

Complications

• Open wounds
• Sepsis
• Fistulas
• Wound dehiscence
• Colostomy/ileostomy
• Short bowel syndrome