Penetrating Abdominal Trauma Clinical Presentation

The history provides clues to the most likely injury patterns and potential management priorities. Emergency medical services (EMS) personnel are often essential in providing a history, especially in a critically ill patient or one with altered mental status.

A common acronym describing important information to gather when taking the history is AMPLE, as follows:

• Allergies
• Medications
• Prior illnesses and operations
• Last meal
• Events and environment surrounding injury

The anatomic location of injury and type of weapon (ie, gun, knife) direct the diagnostic process. Information such as the number of gunshots heard or the number of times the patient was stabbed, and the patient’s position at the time of injury help describe the trajectory and path of the injuring object.

Close-range injuries transfer more kinetic energy than those sustained at a distance, although range is often difficult to ascertain when assessing gunshot wounds.

Blood loss at the scene should be quantified as accurately as possible from EMS personnel. However, research has shown that this assessment is very difficult and rarely reliable. The character of the bleeding (eg, arterial pumping, venous flow) may assist in determining whether major vascular injury has occurred.^[9]

The initial level of consciousness or, for moribund patients, the presence of any signs of life at the scene (ie, pupillary response, respiratory efforts, heart rate or tones) is vital to determine the prognosis and to guide resuscitative efforts. Particularly important is the patient's response to therapy en route to the ED. Evidence of hypotension in the field should raise suspicion for intra-abdominal injury.

Injuries from possible abuse

Pediatric, pregnant, or geriatric patients whose injury occurs in the home may be victims of child abuse, domestic violence, or elder abuse, respectively. Failure to inquire about possible abuse or neglect in such cases is an error of omission and one for which the physician may be held legally accountable.

Mandatory reporting may be required for each of these types of abuse, although specific reporting requirements vary by patient population and locale. For example, statewide databases include external cause of injury codes (E-codes) for the coding and tracking of these injury mechanisms.

Assessment of the patient begins at the scene of the incident by EMS personnel. Upon arrival at the emergency department (ED), communication of the incident history and the patient’s vital signs to the emergency or trauma team is of paramount importance.

The initial physical examination begins with visual assessment of the patient during transport into the ED, with particular focus on the ABCs. Rapid determinations regarding respiratory effort, perfusion, external hemorrhage, and consciousness level are usually easily made. Confounding injuries or medical problems, such as tension pneumothorax or acute myocardial infarction, need be excluded.

Initial vital signs assist in determining injury severity and need for operative intervention. Hypotension, narrow pulse pressure, tachycardia, high or low respiratory rate, or signs of inadequate end organ perfusion in the setting of penetrating abdominal trauma provide evidence of significant intra-abdominal injury, especially vascular trauma, and warrant immediate surgical exploration.

Examination of the abdomen in a patient who is awake may indicate peritoneal signs, such as pain and guarding and rebound tenderness. Hemodynamically stable patients with penetrating abdominal trauma and peritonitis can be assumed to have a hollow visceral perforation and may have significant intra-abdominal hemorrhage. Thus, peritonitis on physical examination is a trigger for emergent intervention regardless of vital signs.

Peritoneal signs develop when the peritoneal envelope and the posterior aspect of the anterior abdominal wall are both inflamed. The peritoneal or retroperitoneal blood and organ contents inflame deeper nerve endings (visceral afferent pain fibers) and result in poorly defined pain. Irritation of the parietal peritoneum leads to somatic pain, which tends to be more localized; however, the diffuse nature of intra-abdominal spillage often leads to diffuse findings.

Referred pain may provide a clue to organ damage. For example, left shoulder pain may result from a damaged spleen with subphrenic blood.

Abdominal distention in an unresponsive patient may indicate active internal bleeding. In hypotensive patients, this may be an indication for immediate exploration. Focused Assessment With Sonography for Trauma (FAST) examination can be useful in this situation to detect massive hemoperitoneum.

Rectal examination is performed on all patients with penetrating abdominal trauma, because blood per rectum and, in males, high-riding prostate can indicate bowel injury and genitourinary tract injury, respectively. Notation of blood at the urethral meatus is also a sign of genitourinary tract injury.

Physical examination includes inspection of all body surfaces, with notation of all penetrating wounds. Multiple wounds may represent either entrance or exit wounds and must not be labeled as such, since multiple missiles or foreign objects may be retained within the body.

Wounds located on the anterior abdomen can be explored locally to determine whether they penetrate the peritoneum. On the flank area and back area, exploration is more difficult and less reliable. Therefore, flank and back wounds are not explored and are considered penetrating unless obviously superficial.

When immediate operative intervention is not requisite, further evaluation ensues with laboratory testing and diagnostic and imaging studies.

Patients without recordable cardiac activity upon presentation should not be further resuscitated.

Primary survey

The primary survey is defined by the mnemonic ABCDE: Airway, Breathing, Circulation, Disability, and Exposure/Environment. Although described sequentially, much of this evaluation may be performed simultaneously and problems identified are managed immediately.

The airway is assessed immediately for patency, protective reflexes, foreign body, secretions, and injury. Breathing is assessed by determining the patient's respiratory rate and by subjectively quantifying the depth and effort of inspiration.

The circulation assessment begins with an evaluation of the patient's mental status, skin color, and skin temperature. Patients in significant hemorrhagic shock will progress from anxiety to agitation and finally coma if their blood loss continues unabated. The traditional vital signs of heart rate, blood pressure, and respiratory rate are not sensitive or specific for hemorrhagic shock.

Disability is assessed early to document neurologic deficits before giving sedation or paralytics. The Glasgow Coma Score and the gross motor and sensory status of all 4 extremities should be determined and recorded. The physician should recognize the need for cerebroprotection measures in cases of brain injury. Hypotension and hypoxemia exacerbate secondary brain injury and increase mortality by 50% in patients with traumatic brain injury.

Exposure is particularly important in the patient with a traumatic mechanism of injury, in whom it may disclose additional, potentially life-threatening injuries. Complete exposure and head-to-toe visualization is mandatory in a patient with penetrating abdominal trauma. This includes the buttocks, posterior legs, scalp, posterior part of the neck, and perineum. There is little to be gained by practicing spinal immobilization unless spinal injury is obvious.

Once the primary survey is complete, a complete head-to-toe physical examination is performed as an integral part of the secondary survey, including digital rectal and genital examinations. This detailed examination may need to be delayed until after operative therapy has corrected obvious life-threatening injury.

Secondary survey and injury assessment

External inspection for injuries with respect to anatomic landmarks aids identification of possible intracavitary injury.

Common physical examination recommendations include evaluation for tympany (a bell-like or percussive note upon gently tapping on the abdomen), dullness to percussion, and bowel sounds. Abdominal distention, not clearly due to "bagging" or swallowed air, may be an indicator of an intra-abdominal catastrophe. A vascular injury is often found in combination with hollow or solid viscus penetration or devitalization.

The physical examination is a more reliable indicator for surgical intervention with penetrating abdominal trauma than with blunt trauma. At many trauma centers, repeated abdominal examinations are the preferred approach for managing hemodynamically stable patients with penetrating abdominal stab wounds.

When selective nonoperative management is used, the indications for operative intervention include the development of hemodynamic instability or the development of increasing pain, peritoneal findings (eg, point tenderness, involuntary guarding, rebound tenderness), or diffuse and poorly localized pain that fails to resolve.

Evisceration has historically been a clear indication for operative management. However, some centers replace eviscerated omentum and serially observe or image these patients.

Impaling objects may tamponade otherwise uncontrolled hemorrhage if the object resides within or crosses a major vessel or solid organ such as the portal vein or liver. Therefore, penetrating objects should not be removed except where definitive treatment can be provided.

For patients with abdominal stab wounds, a policy of observation and serial examination with discharge in 10-12 hours of patients with negative findings has been proposed. While studies have shown promising results, this approach has not been fully validated in multiple centers.^[10]

Pregnancy

The evaluation of penetrating trauma in the pregnant patient needs to be a coordinated, multidisciplinary effort. Trauma in pregnancy is currently a leading cause of nonobstetric maternal death, and maternal death is the most common cause of fetal death. However, while maternal death rate following penetrating abdominal trauma is 10%, fetal death rate nears 80%.

Anterior abdominal penetrating injury commonly results in injury to the uterus and fetus in the last half of pregnancy. Gunshot wounds have a higher mortality for both mother and fetus.^[11]

As pregnancy advances into the second trimester, the gravid uterus moves into the abdominal cavity and out of the protected position in the bony pelvis wherein a pregnancy-specific pattern of injury develops. Superiorly displaced visceral organs are less likely to be injured overall, but they are at greater risk when penetrating trauma involves the upper abdomen. Penetrating trauma to the upper abdomen is worrisome for maternal bowel injury, and many authorities strongly believe that upper abdominal injuries should be operatively managed.

Conversely, the uterus and fetus are at significantly increased risk for direct injury as they grow toward the diaphragm. This likely results from the protective effect of the large, muscular uterus on visceral organs. Because trauma over the uterus has a higher risk of fetal injury, an individualized approach has been advocated and may be better suited for lower abdominal injuries.

Gunshot wounds produce transient shock waves and cavitations in displacement of kinetic energy to body tissue, causing more severe injury than a low-velocity knife injury. Stab wounds to the abdomen are less common than gunshot wounds in the pregnant patient, and they have a lower mortality for both mother and fetus.

Fetal mortality generally results from either premature delivery or direct fetal injury by the foreign body. As in blunt trauma, the biophysical status of the fetus should be evaluated by ultrasonography early in the resuscitation after maternal injuries have been stabilized.

The standard of care is to prioritize the emergent treatment of the gravid patient above that of her fetus. However, a definitive role exists for perimortem cesarean section.

Usual criteria for perimortem cesarean section include a fetus of more than 26 weeks' gestational age (fundal height >26 cm above the pubic symphysis or halfway between the xiphoid and the umbilicus) and a dead or moribund mother. In one review of predictors of fetal survival following such a procedure, more than 70% of surviving fetuses were delivered within 5 minutes of maternal death.

Perimortem cesarean section is a heroic attempt at fetal preservation; the viable fetus that is greater than 26 weeks and has heart tones has a 40-70% chance of survival. More than a 20-minute delay between maternal death and fetal delivery usually results in fetal demise. Care must be taken when interpreting this data, as many of the patients included in the studies of perimortem cesarean sections had experienced blunt trauma.^[12]

Well-planned preparation is essential to ensure fetal survival should a postmortem cesarean section be indicated. Ideally, an obstetrician should perform the procedure; however, a trauma surgeon or the ED physician also may deliver the fetus in this circumstance, especially when no obstetric support is emergently available.

Every woman who sustains penetrating abdominal (or other) trauma should be questioned specifically about domestic violence. The incidence of domestic violence increases during pregnancy and is clustered during the third trimester.

Geriatric patients

Geriatric patients respond to trauma and shock differently than their younger counterparts, owing to the presence of comorbid conditions, decreased physiologic reserve, elasticity of the vascular system, and concomitant medication use. The decreased physiologic reserve reduces the ability to respond to injury or tolerate aggressive resuscitation, while polypharmacy can alter the hemodynamic response to shock and complicate the patient’s clinical picture. Therefore, the unique characteristics of the geriatric patient often result in under-evaluation of risk and resuscitation status because the absence of tachycardia and hypotension is often misleading. Serum lactate measurements are a better reflection of shock and the response to resuscitative efforts than traditional vital signs in elderly patients.

Trauma in the elderly population should always prompt a search for underlying causes if the precipitating cause is not readily apparent (eg, assault).

Elder mistreatment should always be considered when evaluating trauma to older persons that occurred at their residence. A home safety evaluation as part of a social service inquiry into the appropriateness of home support systems should be conducted.

Pediatric patients

Penetrating injuries account for 10-20% of all pediatric trauma admissions at most centers. Gunshot wounds are responsible for the overwhelming majority of penetrating traumatic injuries and have a significantly higher mortality rate than do blunt mechanisms.

Management approaches have been derived largely from the adult experience. A paucity of literature is dedicated to pediatric penetrating abdominal trauma. However, application of adult strategies to similar life-threatening injuries in the pediatric population has been generally found appropriate.^[13]

Adult trauma facilities usually have the capability to triage, treat, and stabilize pediatric trauma patients. Transfer guidelines should be established delineating what types of injury complexes are appropriate for the surrounding pediatric facilities.

Consider child abuse during the evaluation of all pediatric trauma patients with suspicious injuries or circumstances. Social workers well versed in investigating child abuse are invaluable in this situation.

Evidence preservation

Gunshot and stab wounds are usually reportable injuries at the time of the incident, though this may vary by jurisdiction. In the trauma room, care should be taken not to destroy the clothing and in particular to cut around and not through bullet holes, to turn over to law enforcement any foreign body recovered from the patient, and to describe precisely, or even to photograph, any entrance or exit wounds.

Iatrogenic injury

Truthful documentation of iatrogenic injury that occurred during an indicated course of therapy is the best policy. Technical complications are known to occur with a finite frequency. The key is to identify that an error was made and that it was corrected in a timely fashion. This information should be documented extensively in the medical record, explained to the family, and communicated to the appropriate section head and risk management specialist.

Missed injury

Missed injuries occur most commonly in minimally or maximally injured patients (especially patients transferred from nondesignated facilities); the former is due to minimal physical findings, while the latter is due to appropriate diversion of attention to life-threatening priorities. A team approach to caring for trauma patients coupled with algorithmically driven care plans, including the performance of a tertiary survey, minimizes missed injuries.

Many missed injuries are of little consequence in terms of disability or hospital length of stay. However, a missed intestinal injury that results in fulminant peritonitis and sepsis carries a prohibitive cost to the patient, physician, and hospital. When in doubt, obtain a consultation from the trauma service or a reliable imaging study to rule in or out the concerns of injury. This practice serves to further document medical thought processes and may uncover an otherwise occult injury.