Abdominal trauma accounts for 15% to 20% of all trauma deaths.¹ Although the liver is the most frequently injured abdominal organ, the spleen is the most frequently injured intra-abdominal organ from sports accidents.² Death may occur as a consequence of massive hemorrhage and generally results in early demise soon after the injury. Patients who survive the initial traumatic insult are at risk for infection and suffer mortality or morbidity secondary to sepsis.

BLUNT ABDOMINAL TRAUMA

The most common mechanism for blunt abdominal trauma is a motor vehicle collision.¹ All abdominal structures are at risk, and ultimately the biomechanics of the traumatic force determine which organs are affected. Compressive, shearing or stretching, and acceleration/deceleration forces impact the abdominal cavity differently. This potentially leads to abdominal wall, solid organ, or hollow viscous injuries. Abdominal organs may be relatively mobile or fixed. Injury is common in transition areas between these structures. The ligament of Treitz and the distal small bowel represent transition areas where mesenteric or small bowel injuries may occur.

Falls from significant heights produce injury as a function of the fall distance, the surface the victim lands on, and the manner of surface impact. Hollow viscous rupture is the typical intra-abdominal injury.³ Retroperitoneal injury and hemorrhage may occur as force is transmitted along the axial skeleton.

Pedestrians struck by vehicles or motorcyclists and bicyclists who crash generally have no protection to their abdomen and are at high risk for intra-abdominal injuries.

PENETRATING ABDOMINAL TRAUMA

Stab and gunshot wounds produce injury as the foreign object passes through tissue. With gunshot wounds, there may be additional injury from the transmitted energy of the blast. Furthermore, gunshot wounds create secondary missiles such as fragmented bone that may increase the traumatic burden.

The length, trajectory, and fragmentation of the penetrating object will not necessarily be known during the evaluation. Therefore, assume any penetrating injury to the lower chest, pelvis, flank, or back to have penetrated the abdominal cavity until proven otherwise.

Clinical signs may be obvious (such as evisceration) or occult. Factors making the diagnosis of an abdominal injury challenging include concomitant injuries (particularly significant head injuries), referred pain, intoxication with alcohol or other toxicological substances, or language barriers. Young, healthy patients may be able to compensate for intra-abdominal hemorrhage before clinical signs become overt.

PHYSICAL EXAMINATION

Inspect the abdomen for external signs of trauma (e.g., abrasions, lacerations, contusions, seatbelt marks). A normal-appearing abdomen does not exclude serious intra-abdominal injury. Cullen’s sign and Grey Turner’s sign (periumbilical and flank ecchymosis) generally represent delayed findings of intraperitoneal bleeding. Following inspection, palpate the abdomen in all quadrants, making note of tenderness, tympany, or rigidity. For patients who are observed in the ED, serial assessments by the same provider are ideal.

Abdominal tenderness, rigidity, distention, or tympany may not be present during the initial examination and may take hours or days to develop. Reliance on physical exam alone, particularly with a worrisome mechanism of injury, may result in an unacceptably high misdiagnosis rate. As many as 45% of blunt trauma patients thought to have a benign abdomen on initial physical exam are later found to have a significant intra-abdominal injury.⁴

ABDOMINAL WALL INJURIES

Contusions of the abdominal wall musculature may result either from a direct blow or indirectly via a sudden muscular contraction. Symptoms include pain with flexion and rotation of the trunk as well as focal tenderness to percussion. Rectus abdominis hematomas may mimic intra-abdominal injury. Rectus hematomas occur from epigastric trauma or injury to the vessels of the abdominal wall. As a hematoma develops between the rectus sheath, the patient develops pain and often a palpable mass inferior to the umbilicus.²

SOLID ORGAN INJURIES

Signs and symptoms of a solid organ injury are generally due to blood loss. An increase in pulse pressure may be the only clue to loss of ≤15% of total blood volume. As blood loss continues, heart and respiratory rate increase. Hypotension may not occur until a 30% decrease in circulating volume occurs. At this point, urinary output drops and patients may become anxious and confused. With some injuries, pain and bleeding may be minimal and overlooked or dismissed. Delayed rupture can occur in splenic and hepatic injuries.

Splenic injuries may cause referred pain into the left shoulder or arm. Patients with liver injuries may complain of right shoulder pain. Pregnancy and mononucleosis are conditions that may predispose a patient to splenic injuries.

HOLLOW VISCOUS AND MESENTERIC INJURIES

In blunt abdominal trauma, the incidence of blunt bowel and mesenteric injuries varies (1% to 12%) but occurs in about 5% of patients.^5,6 Hollow viscus injuries produce symptoms from the combination of blood loss and peritoneal contamination by GI contents. Hemorrhage from a mesenteric injury may be minimal and not be obvious on physical exam. Chemical irritation of the peritoneum from gastric acid contents may produce immediate pain, although bacterial contamination of the abdominal cavity may result in delayed signs and symptoms. Delays in diagnosis and operative management are associated with an increase in mortality.⁶

RETROPERITONEAL INJURIES

The retroperitoneal structures discussed in this chapter include the pancreas (excluding the tail) and duodenum. See “Genitourinary Injuries” for a discussion of kidney, ureter, and bladder injuries.

Pancreatic injuries are present in approximately 4% of patients with abdominal trauma and are associated with significant morbidity and mortality.⁷ There are no specific signs and symptoms of pancreatic injury, but mechanism of injury provides some clues to diagnosis. Pancreatic trauma often occurs from rapid deceleration. Unrestrained drivers who hit the steering column or bicyclists who fall against a handlebar are at risk for pancreatic injuries. Initial symptoms may be delayed if the injury is minor.

Duodenal injuries may be relatively asymptomatic on presentation, and a small hematoma of the duodenum may go undiagnosed. As a duodenal hematoma expands, however, signs and symptoms of gastric outlet obstruction develop (abdominal pain, distention, and vomiting). Duodenal rupture generally occurs following high-velocity deceleration events where the intraluminal pressure of the pylorus and proximal small bowel rapidly increases. The ruptured contents are generally contained within the retroperitoneum and may be missed with studies that investigate the peritoneum exclusively. For patients with a delayed presentation, fever and leukocytosis herald the development of an abscess or sepsis.

DIAPHRAGMATIC INJURIES

The diaphragm may spasm secondary to a direct blow to the epigastrium. The patient will experience difficulty breathing as the diaphragm loses its ability to relax and allow the lungs to expand. This process is sometimes referred to as “getting the wind knocked out.” As the diaphragm relaxes, symptoms abate.

Diaphragmatic rupture may result from a penetrating injury or blunt force mechanism. The condition is uncommon (0.8% to 5% of patients with thoracoabdominal injury) and is almost exclusively a left-sided phenomenon.⁸ Signs and symptoms are nonspecific and may be attributed to associated injuries. Failure to diagnose and treat diaphragmatic rupture may lead to delayed herniation or strangulation of abdominal contents through the diaphragmatic defect.

Although multiple diagnostic modalities exist to detect intra-abdominal injuries, no study is fail proof. Therefore, a combination of careful physical exam, attention to the mechanisms and circumstances of injury, and judicious selection of diagnostic studies is used for diagnosis. Hemodynamic instability may limit the utilization of some diagnostic testing before definitive treatment is initiated (such as laparotomy or transfer to a trauma center).

Not every patient with multisystem or isolated abdominal trauma will need a diagnostic evaluation beyond a physical exam. However, because the consequences of a missed intra-abdominal injury may be significant, augment an initial exam with laboratory analysis, imaging study, or repeat examination in several conditions (Table 263-1).