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  A normal physical examination cannot be used as the sole means to exclude significant injury in patients with abdominal trauma.

  
  
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  Hemodynamically unstable patients with penetrating injuries into the peritoneal cavity or blunt abdominal trauma and evidence of intraperitoneal hemorrhage require emergent laparotomy.

  
  
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  Gunshot wounds that violate the peritoneum require operative exploration because of the high likelihood of injury.

  
  
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  In patients with blunt abdominal trauma, negative computed tomograhy imaging has an excellent negative predictive value for excluding significant injury.

Victims of abdominal trauma can present with intraperitoneal, retroperitoneal, and intrathoracic injuries. Intraperitoneal structures at a high risk of injury include the solid organs (liver and spleen), hollow viscera (small and large intestines), and diaphragm, whereas commonly involved retroperitoneal structures include the kidneys and genitourinary (GU) tract, duodenum, pancreas, and portions of the large intestine. The initial evaluation and management of patients with abdominal trauma can be divided by the mechanism of injury into blunt and penetrating pathways. Motor vehicle collisions (MVC) and significant falls account for the majority of cases of blunt abdominal trauma, whereas stab wounds (SW) and gunshot wounds (GSW) account for most cases of penetrating trauma. Keep in mind that the location of an entrance wound can frequently be misleading. Although a wound located on the anterior abdomen is obviously a high-risk injury, alternative sites (lower chest, pelvis, back, or flank) can also result in significant intraperitoneal (or retroperitoneal) injury depending on the trajectory of the bullet, knife, or other wounding implement.

When evaluating patients with penetrating trauma, the abdomen can be divided up into 4 distinct zones to help predict which anatomic structures are at risk of injury. The anterior abdomen extends between the anterior axillary lines from the costal margins down to the inguinal ligaments (Figure 88-1). The thoracoabdominal region extends circumferentially around the entire trunk between the costal margins inferiorly and the nipple line or inferior scapular borders superiorly (Figure 88-2). Trauma to this region can injure intrathoracic and intraperitoneal structures as well as the diaphragm. The flanks compose the third anatomical zone and extend between the anterior and posterior axillary lines from the costal margins to the iliac crests. Consider injuries to both intraperitoneal and retroperitoneal structures in this region. The final anatomical zone is the back, which extends between the posterior axillary lines from the inferior scapular borders to the iliac crests. Trauma to this region is most likely to result in retroperitoneal injury.

MVCs account for the majority of cases of significant blunt abdominal trauma across all demographic groups, with the spleen by far the most commonly involved organ. With penetrating trauma, abdominal SWs are roughly 3 times more common than GSWs. That said, the latter accounts for roughly 90% of fatal injuries, as SWs are far less likely to violate the peritoneal cavity and cause significant injury. Abdominal GSWs most commonly involve the small bowel, colon, and liver, as these organs take up the largest volume within the abdominal cavity. Abdominal SWs most commonly affect the liver, but laparotomy is required in only one quarter to one third of patients.

The severity of injury is proportional to the amount of energy transferred to target tissues. Blunt abdominal trauma causes injury primarily by the direct transmission of external forces to underlying organs. Solid viscera, namely the spleen and liver, are the most likely structures to be involved. Hollow viscera can be injured when sudden crushing forces induce a rapid spike in intraluminal pressure and secondary rupture. Blunt trauma can also transmit shearing forces to underlying structures. Significant injury is most commonly seen in areas of transition from fixed to mobile positions such as the small bowel at the ligament of Treitz or the ileocolic junction.

In penetrating trauma, SWs result in low-energy mechanisms that cause injury only to those tissues directly impacted by the stabbing implement. As most assailants are right-hand dominant, the left upper quadrant is the most likely region to be affected. GSWs, on the other hand, transmit substantial amounts of energy and frequently result in significant intra-abdominal injury. Missile size, stability, and velocity all help to determine the amount of energy imparted. High-velocity projectiles (>2,000 ft/sec) as seen with combat wounds and hunting rifles can create waves of energy that result in temporary cavity formation and the disruption of tissues remote from the missile tract. In fact, intraperitoneal injury has been known to occur with high-velocity GSWs in the absence of peritoneal violation. Shotgun injuries are unique in that the velocity of the pellets decreases rapidly with the length of distance traveled. Furthermore, the spread of the pellets increases proportionally to the distance between the victim and the shooter. Wounds with a pellet spread of 10–25 cm most likely occurred at a distance of 3–7 yards and possess sufficient energy to penetrate into the peritoneal cavity. Finally, the potential for introducing contamination in the form of clothing or wadding further complicates GSW injuries.

History

A rapid primary survey and patient stabilization should always take precedence over a thorough medical history. That said, obtain a quick AMPLE (Allergies, Medications, Past illnesses, Last meal, Events preceding injury) history as with all trauma patients and ask focused questions to delineate the potential severity of mechanism. Emergency medical service personnel can provide invaluable information about the mechanism of injury, initial scene evaluation, and response to interventions provided during transport. With patients from an MVC, inquire about the severity of vehicular damage, seatbelt use, airbag deployment, need for patient extrication, and injuries to other occupants. For GSW victims, ask about the number of shots fired and the type of weapon involved.