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A team approach in the evaluation and treatment of abdominal injuries, that includes the emergency physician, trauma surgeon, anesthesiologist, and surgical subspecialists, is ideal. In reality, many emergency physicians find themselves as the only physician initially and must approach the injured child in a systematic way, utilizing consultants expeditiously. Blunt abdominal injuries rarely require surgical intervention, whereas penetrating trauma frequently does. Nevertheless, all unstable patients need immediate surgical consultation.
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The basic principles of trauma evaluation and resuscitation should be followed in all cases of abdominal trauma. Evaluation of the abdomen is included in both the primary and secondary surveys. The following interventions are particularly important:
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Insert a nasogastric or orogastric tube to decompress the stomach and to check for blood or bile. Insert an orogastric tube if there is any suspicion of head trauma or basilar skull fracture.
Place a urinary catheter to check for blood and urinary retention, if there is no gross blood at the meatus. Obtain a urinalysis.
Complete a rectal examination to check for blood, prostate position in males, and rectal tone.
Keep the child NPO because of the possibility of surgery or development of paralytic ileus.
Blood should be obtained for type and cross-match, electrolytes, CBC, serum amylase, and liver transaminases.
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The mechanism of injury is important and guides the secondary survey and the ordering of specific tests or procedures. It is always important to log roll the patient to inspect the posterior torso for additional wounds. External injuries such as abrasions, lacerations, bruising, and characteristic markings such as tire tracks and seat belt marks should be noted.
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Children respond differently to trauma and stress. A traumatized child may be more difficult to examine and may not show the familiar signs of impending demise as seen with adults. History may be limited and the child's reaction to pain may be difficult to assess. Designate a team member or the parent or caregiver at the bedside to take care of the child's emotional needs and to comfort them through the ordeal of trauma evaluation and treatment. Over the past decade, many pediatric trauma centers have instituted policies on family member presence for trauma and pediatric resuscitation.6–8
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Penetrating Abdominal Trauma
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The diagnosis and treatment of penetrating abdominal injuries in children does not differ greatly from that for adults, and initial management is not dependent on identifying any specific injury. The hollow organs, because of their large volume, are most commonly injured, followed by the liver, kidney, spleen, and major vessels.
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In children, the abdomen begins at the nipples, so penetrating wounds between the nipples and the groin potentially involve the peritoneal cavity and should be considered contaminated. Location, size, and possible trajectory of entrance and exit wounds help to identify potential underlying injuries. Surgical evaluation, wound debridement, and possible exploration, along with broad-spectrum intravenous antibiotics, are necessary in all but the most minor of wounds. At a minimum, the following should be performed with significant penetrating abdominal trauma: placement of a nasogastric or orogastric tube; placement of a urinary catheter; upright and lateral (if possible) chest radiograph; supine, upright, and cross-table abdominal radiographs; obtain a CT scan of the abdomen with IV contrast for deep-penetrating stab wounds and all gunshot wounds unless their clinical condition is unstable and they need to go directly to the operating room. Gunshot wounds to the abdomen require immediate exploration. Most enter the peritoneal cavity and injure organs directly or indirectly through kinetic energy dissipation. The high morbidity and mortality associated with gunshot wounds is due to the destructive force of the missile and its fragments, rapid blood loss, complicated surgical repair, and postoperative complications.
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Stab wounds pose the greatest threat to blood vessels. Commonly injured vessels include the aorta, inferior vena cava, the portal vein, and hepatic veins. However, stab wounds enter the peritoneal cavity only one-third of the time and only one-third of these require a visceral repair.
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Local exploration may be possible to rule out peritoneal penetration in minor stab wounds. Conservative management can be entertained if the patient meets the following criteria:
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No sign of shock or peritonitis with observation for 12 to 24 hours
No blood in the stomach, rectum, or urine
No evidence of free abdominal or retroperitoneal air on x-ray
No history or evidence of bowel or omental evisceration
Close observation with surgical consultation
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Blunt Abdominal Trauma
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Both isolated abdominal and multisystem trauma present challenges in the pediatric patient because information is inherently difficult to obtain. Multiple other injuries may overshadow often subtle early abdominal findings and the physical examination may be only 55% to 65% accurate. Minor mechanisms, such as falling from 2 ft to the ground, can still result in significant injury with minimal symptoms. Therefore observation, as well as repeat vital signs and serial abdominal examinations, may be warranted. Laboratory and radiologic studies may be necessary depending on clinical status, mechanism of injury, and suspicion for injury on physical examination.
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Radiographs of the chest (supine or preferably upright posteroanterior plus a lateral) and supine abdomen and pelvis can give important clues to the diagnosis of abdominal injury (Table 26-2).
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Laboratory Evaluation (Diagnostic Studies)
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The child with blunt trauma is at high risk for intra-abdominal injury if any of the laboratory or physical examination findings listed in Table 26-3 are present.9 Hemoglobin and hematocrit are seldom useful early in the evaluation, but may be valuable for comparison to baseline later in the management of the patient. However, if the initial hematocrit is <30% with other signs of impending shock, this suggests significant hemorrhage.9 An initial hematocrit <24% is associated with high mortality, and transfusion should be initiated immediately.
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A persistently distended abdomen after nasogastric tube placement, hemodynamic instability not immediately responsive to fluid resuscitation, recurrent hypotension, or signs of peritoneal irritation warrant immediate surgical intervention by a surgeon experienced in pediatric abdominal injuries.
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Computed tomography (CT) scan has eliminated much of the difficulty surrounding the diagnosis of abdominal injuries and is the procedure of choice for stable trauma patients. Specialized studies should be ordered in consultation with the trauma surgeon to avoid unnecessary delay in definitive treatment. Indications for abdominal and pelvic CT scan are listed in Table 26-4. CT scan is useful for evaluation of the liver, kidney, spleen, retroperitoneum, and, to a lesser extent, gastrointestinal injuries. CT scan identification of pancreatic injury, diaphragm injury, and bowel perforation are much less sensitive and warrant a high index of suspicion with serial abdominal examinations to rule out occult injury.
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Radiation exposure is the greatest risk associated with CT scan.10 Abdominal CT scan carries a significant lifetime cancer mortality risk with radiation-attributable risks from a single abdominal CT scan within the first and tenth years of life estimated at 1/550 and 1/700, respectively.11,12 Variation in practice with respect to CT scan of the child with blunt abdominal trauma persists. Clinical decision rules are necessary to reduce variability in medical management by providing evidence-derived guidelines for clinical care; thereby, decreasing unnecessary radiation exposure.13,14
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The Pediatric Emergency Care Applied Research Network (PECARN) recently derived a prediction rule to identify children at very low risk for intra-abdominal injuries undergoing acute intervention and for whom CT can be obviated.
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This clinical prediction rule consists of seven patient history and physical examination variables, easily available to clinician. The PECARN prediction rule for IAI was derived in over 12,000 children and had excellent performance characteristics with a negative predictive value of 99.9% and sensitivity of 97%; however, external validation of the rule is pending. The clinical prediction rule included the following seven variables in descending order of importance:
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No evidence of abdominal wall trauma or seat belt sign
Glasgow Coma Scale Score > 13
No abdominal tenderness
No evidence of thoracic wall trauma
No complaints of abdominal pain
No decreased breath sounds
No vomiting
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In instances when abdominal CT is obtained and is negative, it might be safe to discharge a stable child home due to the high negative predictive value of abdominal CT for detection of intra-abdominal injury.15,16
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Use of oral and intravenous contrast media has traditionally been thought to increase the sensitivity of abdominal CT scan. However, oral contrast is rarely used in the trauma setting because of the technical difficulty of administration and increased waiting time before scanning, risk of aspiration, and apparent limited value because of frequent lack of bowel opacification.17
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Diagnostic Peritoneal Lavage
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Close observation, serial physical examinations, and particularly abdominal CT scan are utilized to the virtual exclusion of peritoneal lavage in pediatric patients. Diagnostic peritoneal lavage (DPL) may still be useful if these other modalities are unavailable or the child must undergo immediate general anesthesia for other injuries. Under these circumstances, DPL can often be performed in the operating suite. However, the usefulness of DPL remains questionable. It is neither organ-specific nor injury-specific, and cannot reliably assess retroperitoneal injury, and the decision to operate for liver or splenic injuries is not based on the amount of intraperitoneal blood in children. In addition, the introduction of air and fluid into the abdomen and the resulting peritoneal irritation make subsequent physical and radiographic examinations more difficult.
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The technique for DPL in children is similar to that for adults, although a small supraumbilical incision to avoid the bladder is preferred in young children over the usual infraumbilical approach.
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Bedside ultrasound (US) is more readily available and has significantly reduced the need for DPL. It is particularly useful in the unstable patient as an immediate triage tool and adjunct to the physical examination. As such, it is best used for detecting intra-abdominal injuries that require immediate attention (such as in the setting of hypotension) rather than for a definitive diagnosis.18–21 It is also useful when CT scan is not available and its greatest utility is in detecting intraperitoneal hemorrhage and pancreatic injuries. Overall, CT scan is more sensitive than US at detecting intra-abdominal injury in children.22–24 In addition, a highly experienced ultrasonographer is required to improve the sensitivity of the pediatric abdominal US. Abdominal US has 66% to 83% sensitivity for the detection of hemoperitoneum in the pediatric trauma patient and CT scan is recommended in the presence of a positive US.25
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The use of bedside US has become part of the core emergency medicine curriculum and is often taught using the FAST method. The FAST examination evaluates up to six areas of the abdomen with the principal objective of identifying hemoperitoneum. Children who are hemodynamically unstable with abdominal trauma will require laparotomy regardless of the US and those that are stable are often managed nonsurgically even with abdominal organ injury. Therefore, the exact role of US in assessing pediatric abdominal trauma is still being evaluated.