Chapter 25. Abdominal Trauma

Abdominal injuries are potentially life-threatening and should be approached with caution. Following trauma, the abdomen may be a sanctuary for a broad spectrum of injuries that, if not discovered and corrected expeditiously, may lead to deleterious consequences. Traditionally these injuries are classified as either blunt trauma or penetrating injuries. The majority of blunt abdominal trauma is secondary to motor vehicle collisions, whereas the majority of penetrating injuries is predominantly secondary to gunshot or stab wounds. Patients with abdominal trauma require rapid assessment, stabilization, and early surgical consultation when indicated to maximize the chances of a successful outcome.

Assessment

Initial management of all trauma patients is the same, and abdominal trauma is no exception. Following ATLS protocols, begin the assessment with a rapid primary survey, including evaluation of the airway, breathing, circulation, disability, and exposure.

Airway

Assess the airway while maintaining cervical spine immobilization until potential injury is ruled out. Jaw thrust without head extension can be used to open the airway of a trauma patient. Administer high-flow oxygen, and intubate the patient if indicated.

Breathing

First assess breathing by auscultating for breath sounds. Diminished or absent breath sounds should raise clinical suspicion for a possible pneumothorax. Next, inspect for asymmetry of chest wall movement, open wounds, or flail segments. Then palpate the chest wall carefully. Palpable crepitus may indicate a pneumothorax or rib fractures. Rapidly perform needle decompression or tube thoracostomy when indicated (See Chapter 24). Pulse oximetry and capnography may be useful.

Circulation

Assess circulation. If gross external hemorrhage is present, control with direct pressure. Assess pulses, capillary refill, and blood pressure. Obtain intravenous access, preferably with at least two large-bore (≥16-gauge) peripheral catheters. If peripheral intravenous access is inadequate or unattainable, place a central venous catheter or interosseous line. Begin fluid resuscitation. The FAST examination is important at this stage of the evaluation, especially in hemodynamically unstable patients, where a positive FAST exam would be an immediate indication for emergency laparotomy.

Disability

To assess disability, complete a brief and focused neurologic examination to document the patient's current mental status. The examination should include an assessment of pupillary size and reactivity, a determination of the patient's Glasgow Coma Scale score, and notation of any focal neurologic deficits such as unilateral weakness or poor muscle tone. Ideally, assessment of disability should be performed before administering pain medications, sedatives, or paralytics.

Exposure

In order to complete a thorough secondary survey, the patient must be fully exposed. Completely undress the patient while taking precautions to prevent or recognize and correct associated hypothermia. Begin a more thorough secondary survey, including logrolling the patient and examining all skin folds, the back, and axillae for any signs of trauma (eg, contusions, hematomas, abrasions, or penetrating wounds). Attempt to identify all wounds and document their location. To help identify the trajectory of bullets, place a radiopaque marker (eg, paper clip) at the wound site prior to obtaining X-rays. Do not remove impaled foreign bodies because they may be providing hemostasis from a vascular injury. Most foreign body removal should be performed with surgical consultation in a more controlled setting. Describe each wound, and avoid using terms such as entrance or exit wound on initial presentation, because it is often difficult to correctly make this assessment visually. These determinations are best left to a forensic pathologist.

Any penetrating injury below the level of the nipple line warrants evaluation for intra-abdominal injury. For patients involved in motor vehicle collisions, carefully examine the chest and abdomen looking for ecchymosis or erythema in the area of the clavicles or across the abdomen. The classic “seat-belt sign” or linear bruising across the lower abdomen is a marker for intra-abdominal injury, present in approximately 25% of patients with this finding. Examine the abdomen for any tenderness, distention, rigidity, or guarding. It is often difficult to assess bowel sounds at this stage of the examination. Evaluate the pelvis for anteroposterior or lateral instability with gentle pressure; this does not require much force and should not be repeatedly performed. Examine the genitalia and look for blood at the urethral meatus, especially in males. Perform digital rectal examination in any patient with abdominal trauma to look for gross blood, assess sphincter tone, identify a high-riding prostate, and to note any other evidence of trauma. There is no role for occult blood testing acutely in a trauma. If blood at the urethral meatus or a high-riding prostate is present, placement of a urinary catheter is contraindicated and a retrograde urethrogram is required to evaluate for potential urethral injury.

Treatment

Fluid Resuscitation

Hemodynamic support is an early goal in the treatment of trauma patient. The use of crystalloids is currently recommended in trauma resuscitation but the concept of acute fluid resuscitation is evolving and may represent an area of some controversy. Animal and human studies have demonstrated deleterious effects of aggressive fluid resuscitation, particularly if penetrating trauma is present. Rapid infusion of large amounts of crystalloids may disrupt the formation of the soft clot and dilute the clotting factors, leading to increased bleeding. The results are less clear in the setting of blunt trauma. The amount of fluid given should be tailored to each individual patient. Also, blood pressure alone is not the best indicator of the level of shock. Attempts to make the patient normotensive are not recommended. A more reasonable goal may be to obtain systolic blood pressure of 80–90 mm Hg or a mean arterial pressure of 70 mm Hg. Crystalloids remain first-line fluids, followed by infusions of packed red blood cells. Other blood products, such as fresh frozen plasma and platelets, may be indicated in potentially uncontrollable hemorrhage (eg, deep truncal injury.) Recombinant Factor VIIa is used as an adjunct to other blood products in the setting of massive hemorrhage. The CRASH-2 trial, which tested an infusion of tranexamic acid, demonstrated a 9% reduction in death for traumatized patients with suspected hemorrhage whom were given the drug within 8 hours of injury. While certainly not standard of care at this time, this treatment may become widely adopted in next few years as another option to employ in treatment of significant hemorrhage in the setting of trauma.

Indications for Emergency Laparotomy

Most patients with penetrating abdominal injuries will also require laparotomy given the high incidence of intra-abdominal injury once the fascia has been violated. Hemodynamically unstable patients sustaining blunt or penetrating trauma with a positive screening test (such as focused assessment with sonography for trauma [FAST] examination or diagnostic peritoneal lavage [DPL]) require laparotomy to control hemorrhage and evaluate for intra-abdominal injuries. Although there is no debate that patients with peritonitis or hemodynamic instability should undergo urgent laparotomy after penetrating trauma to the abdomen, it is also clear that certain stable patients without peritonitis may be managed without operation. Routine laparotomy is NOT indicated in hemodynamically stable patients with knife stab wounds if there is no evidence of peritonitis or diffuse abdominal tenderness. Routine laparotomy is also NOT routinely indicated in stable patients with gunshot wounds if wounds are tangential and without peritoneal signs. Initially stable blunt trauma patients with identified abdominal injuries should be carefully observed so that if they become hemodynamically unstable they can rapidly receive operative intervention. Laparoscopy for certain penetrating injuries has helped in eliminating nontherapeutic laparotomies. Patients with obvious diaphragmatic injury noted on chest X-ray require emergency laparotomy. Patients considered to be at very low risk for having intra-abdominal injury (particularly intra-abdominal injury requiring acute intervention) have no hypotension, no GCS < 14, no costal margin tenderness, no abdominal tenderness, no hematuria ≥25 RBC/hpf, no hematocrit < 30, and no femur fracture.

Surgical Consultation

It is imperative to seek early surgical consultation in the management of patients with abdominal trauma, especially if the patient is hemodynamically unstable. Many stable patients with blunt abdominal injuries can initially be treated with nonoperative management. Not all blunt and penetrating abdominal injuries require immediate operative intervention but the majority will require observation and repeat examinations at a minimum.

Diagnostic Testing

Laboratory Evaluation

Initial laboratory evaluation in the traumatically injured patient should include hemoglobin, hematocrit, and platelet count to establish a baseline. A blood-type and screen should be ordered in case transfusion of packed red cells is needed. A lactate level may be obtained and, if elevated, is an excellent indicator of shock. Similarly, base deficit is another indicator of shock. The role of amylase or lipase in abdominal trauma is uncertain. Elevation of liver enzymes may indicate hepatic injury. Glucose and white blood cell count are often elevated in acute trauma and are nonspecific findings. Examination of the urine may reveal gross hematuria, which typically suggests significant injury to the urogenital tract (Chapter 26).

Other Diagnostic Modalities

Plain Radiography

Almost all major trauma patients require plain X-rays of the chest, pelvis, and cervical spine. Although rarely used today because of the ubiquity of computed tomography (CT) scanning, a one-shot intravenous pyelogram may be useful in patients with flank wounds or gross hematuria who are unable to undergo further diagnostic testing prior to operative intervention. Plain radiography of the abdomen is generally not helpful other than in penetrating trauma as a means of evaluating the trajectory of a retained intra-abdominal missile.

Diagnostic Peritoneal Lavage

Although DPL has largely been replaced by ultrasonography, clear indications still remain for its use. A positive DPL in hemodynamically unstable patients with potential multisystem trauma allows for expeditious interventions. A negative test in stab wounds supports observation and early discharge. The main concern regarding DPL is that it is overly sensitive for intra-abdominal blood, which has lead to a high rate of negative or nontherapeutic laparotomies. Recent literature, however, has advocated the use of DPL in conjunction with CT scanning or laparoscopy, particularly in low-velocity penetrating trauma (ie, stab wounds), to decrease the number of nontherapeutic laparotomies. If DPL is considered, it should be performed only after consultation with the trauma surgeon, who should perform this diagnostic study in most cases. Current guidelines emphasize the complimentary role of DPL, FAST, and CT scanning for trauma patients.

CT Scanning

In the hemodynamically stable trauma patient, CT scanning is an excellent diagnostic modality that is easy to perform. If significant intra-abdominal injury is suspected and the hospital is not equipped to manage such patients, it is unwise to delay transfer in order to obtain a CT scan, assuming a reasonably expeditious transfer is possible. No diagnostic modality out performs CT in the evaluation of intraperitoneal as well as retroperitoneal injuries. Contraindications to CT scanning in trauma patients include hemodynamic instability or clear indication for exploratory laparotomy.

Ultrasonography

Ultrasonography has emerged as the primary initial diagnostic examination of the abdomen in multisystem injured blunt trauma patients. Emergency ultrasonography has been studied extensively and is rapid and accurate in the identification of intraperitoneal free fluid. It is also safe in special patient populations (eg, pediatrics, obstetrics). Focused Assessment with Sonography for Trauma (FAST) has a high specificity to detect hemoperitoneum. It's main goal is to reduce time to exploratory laparotomy in blunt or penetrating abdominal trauma. FAST examination (see Chapter 6) is a bedside test that has demonstrated good accuracy with relatively minimal operator experience (at least 30 examinations). The standard FAST examination consists of an initial subxiphoid view of the pericardium, followed by examination of the right upper quadrant looking for free fluid in the Morison pouch (hepatorenal space). The Morison pouch is one of the most dependent parts of the abdomen in the supine trauma patient and often shows the first signs of intraperitoneal fluid collection (blood). Subsequently the splenorenal interface in the left upper quadrant (Figure 25–1) is evaluated, followed by the pelvis. Unlike CT, a FAST examination is rapid, can be performed at bedside in the emergency department, and is easily repeatable. In the setting of abdominal trauma, if a patient is hypotensive with a positive FAST exam, they should go directly to exploratory laparotomy. If the patient is hemodynamically stable, further testing, such as CT scan, may be indicated.

Laparoscopy

The use of laparoscopy, with or without CT scanning or DPL, is being studied. It is less invasive than traditional laparotomy and may shorten hospital stays and decrease patient costs, while reducing the number of nontherapeutic laparotomies. As a relatively new modality to evaluate trauma patients, laparoscopy will likely be used more frequently to determine if peritoneal penetration has occurred or if diaphragmatic injury is present in the setting of penetrating trauma. The role of laparoscopy in blunt trauma is also evolving.

Types of Injury

Blunt Abdominal Injury

Blunt injury occurs most frequently with motor vehicle collisions. Injuries occur secondary to shearing, tearing, or direct impact forces. The presence of a “seat-belt sign” is indicative of intra-abdominal injury in at least 25% of cases. It is important to ascertain if only a lap belt was used, especially in children. Lap-only restraints in children predispose them to intra-abdominal injuries such as intestinal perforations and mesenteric tears. Evaluation of the lumbar spine is also recommended as these injuries may be associated with transverse lumbar spine fractures (Chance fractures). After blunt abdominal trauma, if there is a large or moderate amount of free fluid present without evidence of solid organ injury, suspect a hollow organ injury. These patients often require laparotomy.

Penetrating Injuries

Any wound inferior to a line drawn transversely between the nipples should be treated as having the potential for intra-abdominal trajectory. As noted earlier, intravenous fluids should be used judiciously in the prehospital setting. Before arrival at the emergency department, patients should be given enough fluids to maintain a systolic blood pressure of 90 mm Hg, rather than a multiliter resuscitation. If penetrating injuries are present, initiate antibiotic therapy and administer a tetanus booster early in treatment.

Gunshot Wounds

Traditional teaching mandated that all gunshot wounds with an intra-abdominal trajectory required exploratory laparotomy. Some authors have described a less aggressive approach to a carefully selected subset of patients with penetrating trauma to the abdomen including some low-velocity gunshot wounds. Nonoperative management of gunshot wounds that penetrate the peritoneum is controversial. Patients presenting with hypotension despite crystalloid resuscitation will need immediate exploratory laparotomy, blood transfusion, antibiotics to cover abdominal flora, and a tetanus booster. For hemodynamically stable patients, once intraperitoneal invasion has been ruled out, conservative management of wounds that are superficial and tangential to the abdomen may be used. Seek early surgical consultation in all cases of abdominal gunshot wounds.

Stab Wounds

Patients with stab wounds require resuscitation as well as tetanus booster and antibiotics if intraperitoneal violation is suspected. A surgeon should conduct a wound exploration for all but the most superficial wounds, and adequate staff and lighting are required. DPL, CT scanning, and laparoscopy may be used. If peritoneal violation has been ruled out, patients may be safely discharged with local wound care instructions. If the peritoneum has been violated, traditional teaching has mandated exploratory laparotomy. Similar to the management of low-velocity gunshot wounds as mentioned above, some surgeons have begun to observe a carefully selected subset of patients with no obvious signs of intraperitoneal injury on physical examination or identified by imaging modalities such as CT scanning.

1This chapter is a revision of the chapter by Roger Humphries, MD from the 6th edition.

Splenic Injuries

Essentials of Diagnosis

• Common in blunt trauma
• Left upper quadrant pain and tenderness, often with radiation to left shoulder
• May cause significant hemodynamic instability
• CT scan is noninvasive and sensitive in stable patients; use FAST examination or laparotomy for unstable patients
• Delayed rupture may occur

Splenic injuries commonly occur secondary to blunt force trauma. Patients may present with small splenic hematomas, lacerations, devascularization, or complete rupture (Figure 25–2). These injuries are further divided into grading classifications based on the severity of the injury. Most classification schemes grade the injuries based on the size and location of the laceration or hematoma and the presence of active bleeding. For example, injuries that extend into the vascular pedicle or hilum are designated higher grade and are more likely to require splenectomy.

Trauma surgeons have turned away from mandatory operative treatment of all splenic injuries toward more frequent nonoperative management. In the absence of life-threatening hemorrhage, the goal is to preserve the spleen. Hemodynamically stable patients with low-grade lesions may be observed. Nonoperative treatment is the most common method of management for patients with splenic injuries and is the most common method of splenic salvage. Patients are less suitable candidates for conservative therapy and at greater risk for nonoperative failure if they have high-grade injuries or if CT scan demonstrates free pelvic fluid. If hypotension unresponsive to 2 L of intravenous crystalloid infusion is present, blood transfusion should be given and the patient is prepared for surgery. Angiography with selective arterial embolization is used in some centers to control splenic bleeding and avoid laparotomy. All splenic injuries require consultation with a trauma surgeon and admission regardless of the severity.

Diaphragmatic Injuries

(For more details, see also Chapter 24).

Essentials of Diagnosis

• May be secondary to blunt or penetrating forces
• Rupture occurs predominantly on left side
• Often difficult to visualize on initial chest X-ray (nasogastric tube may enhance diagnosis)
• CT scan or laparoscopy more sensitive
• Delays in diagnosis lead to increased morbidity and mortality

The diaphragm may be injured by penetrating or blunt trauma. Diaphragmatic injuries are frequently difficult to detect initially. Blunt diaphragmatic rupture is a rare condition and correct diagnosis remains difficult and is occasionally made late. The presence of abdominal contents in the thorax may not be obvious on initial chest X-ray. Insertion of a nasogastric tube may facilitate the diagnosis (Figure 25–3). However, diaphragmatic ruptures may be missed even on initial CT scan. If abdominal viscera are seen in the thoracic cavity, then the diagnosis is made easy. In hemodynamically stable patients with penetrating left thoracoabdominal trauma, the incidence of injury to the diaphragm is very high and thoracoscopy or laparoscopy is recommended for diagnosis and repair of a missed diaphragmatic injury. Occult diaphragm injury after penetrating thoracoabdominal injury can be difficult to diagnose and can remain occult for months to years. Delayed diagnosis is associated with risk of hernia formation, strangulation, and high morbidity and mortality.

Liver Injuries

Essentials of Diagnosis

• Most common in blunt trauma
• Right upper quadrant pain and tenderness, often with radiation to right shoulder
• May cause significant hemodynamic instability
• CT scan is noninvasive and sensitive in stable patients; use FAST examination or laparotomy for unstable patients

Because of its size and location, the liver is commonly injured in blunt and penetrating abdominal trauma. Nonoperative management has become standard for > 80% of blunt liver injuries. Liver injuries can include lacerations, hematomas, or rupture (Figure 25–4). Small lacerations or hematomas located in the periphery of the liver (Grade I or II) are likely to be managed nonoperatively. However, nonoperative management of high grade liver injuries is associated with significant morbidity and typically is correlated with grade of the liver injury. Unstable patients with liver injuries require laparotomy to attempt hemorrhage control. Because of the significant blood supply from the hepatic artery and portal vein, large defects are technically difficult to manage and may result in exsanguination and death. In cases where operation is required, current operative management emphasizes packing, damage control, and early utilization of interventional radiology for angiography and embolization.

Pancreatic Injuries

Essentials of Diagnosis

• Uncommon, usually seen after blunt trauma
• Patients may present with epigastric or back pain
• Serum pancreatic enzyme levels are not sensitive or specific for injury
• CT scan is noninvasive and sensitive

Although relatively uncommon, traumatic pancreatic injury is associated with significant morbidity and mortality. It is most commonly seen with penetrating trauma. Blunt trauma to the pancreas accounts for only 26% of cases. Pancreatic injuries are rare and often difficult to diagnose. The pancreas may be lacerated or contused. Amylase levels are not specific and often not helpful, particularly early in the evaluation of the patient. CT scan or radiologist-performed ultrasound may be helpful. All patients with traumatic pancreatic injuries should be admitted.

Renal Injuries

(See also Chapter 26)

Essentials of Diagnosis

• Hematuria should raise suspicion for injury
• CT scan is noninvasive and sensitive in stable patients

The kidney may sustain lacerations, contusions, shattering, or devascularization injuries. In the setting of trauma, if there is no blood at the urethral meatus and no high-riding prostate, a urinary catheter is inserted to determine whether gross hematuria is present. Presence of gross hematuria is typically indicative of urologic injury. Microscopic analysis is not needed in adults unless the patient has been hypotensive. In children, the presence of at least five red blood cells per high-power field on microscopic examination indicates possible urinary tract injury. These findings warrant urologic consultation in the emergency department (see Figure 26–5). In patients with renal injuries chosen for nonoperative management, typical causes of failure in conservative treatment include high fever, drop in hematocrit, severe flank pain, and hemodynamic instability.

Bladder Injuries

(See also Chapter 26)

Essentials of Diagnosis

• Most commonly seen with pelvic fractures
• Hematuria should raise suspicion for injury
• Retrograde cystogram may identify injury (as well as associated urethral injury)
• CT scan may also be used with cystogram

Bladder injuries may be either intraperitoneal or extraperitoneal. The diagnosis is suspected in a patient with abdominal pain and gross hematuria and is confirmed with a retrograde cystogram. CT scan can also be diagnostic for traumatic intra-peritoneal bladder rupture if the “sentinel clot sign” abutting on the bladder dome can be detected and localized. Patients with intraperitoneal bladder rupture require emergent urologic consultation and immediate surgery (see Figures 26–6 and 26–7).

Gastrointestinal Tract Injuries

Essentials of Diagnosis

• May occur with blunt and penetrating injuries
• Peritoneal signs may be delayed
• May be missed on initial plain X-rays, ultrasound, and CT scan
• May have delayed presentation (eg, duodenal hematomas)
• Strongly consider the diagnosis in patients with free fluid on CT scan but no specific solid organ injury identified

Both penetrating and blunt trauma can cause gastrointestinal tract (GIT) injuries. Injuries to the GIT may be clinically subtle and are more common with penetrating than blunt trauma. GIT injuries occur in 30% of stab wounds and in 80% of gunshot wounds to the abdomen. In blunt trauma, an abdominal wall bruise or “seat-belt sign” should raise the level of suspicion since this finding is associated with a GIT injury in up to 25% of cases. GIT injuries may be missed on FAST examination or standard CT scan but surgically important bowel and/or mesenteric injury are accurately revealed by multidetector CT scanning (Figure 25–5). The finding of a moderate or large amount of free fluid in the abdomen on CT scan without a specific solid organ injury is highly suspicious of a hollow viscus injury. Such injury may be present even if the patient can tolerate a trial of fluids by mouth in the emergency department. The emergency physician should be cautious if this diagnosis is suspected. Give thorough instructions to the patients who are to be discharged, including planned, early follow-up care. Patients have been able to walk out of the emergency department only to return later with fever and a rigid abdomen. Rare cases of traumatic appendicitis have been reported in the literature. If injuries involving impact, or “spearing,” with bicycle handlebars are present, consider evaluating the patient for a duodenal hematoma, which can often be managed conservatively with only observation in the hospital.

Flank Injuries

Essentials of Diagnosis

• May be associated with renal injuries
• Retroperitoneal hematoma may be false positive on DPL or ultrasound
• CT scan is noninvasive and sensitive in stable patients

Flank injuries are more difficult to manage than other types of injuries because differentiating intraperitoneal from retroperitoneal involvement can be difficult. An abdominal CT scan or one-shot intravenous pyelogram may be beneficial to diagnose ureteral or retroperitoneal injury. Hemodynamically stable patients with penetrating flank wounds with no peritonitis may need CT scan, serial physical exams, and possibly laparoscopy.