Blunt Abdominal Trauma in Pediatrics

Blunt Abdominal Trauma in Pediatrics

Pediatric abdominal trauma is common, with delays in diagnosis and treatment resulting in an increased rate of complications. Advances in technology have made evaluation of intra-abdominal injuries increasingly less invasive, but clinical diagnosis and an appropriate level of suspicion are still the most important variables in management. The authors review common intra-abdominal injuries and the current standard for diagnostic evaluation and management.

— Ann M. Dietrich, MD, Editor

Introduction

Trauma is the number one cause of death in the pediatric age group.1,2 Blunt trauma is much more common than penetrating trauma and can present a serious challenge to care providers.

Blunt abdominal trauma accounts for the large majority of abdominal injuries in the pediatric population. Blunt abdominal trauma far outnumbers penetrating abdominal trauma,3 and the mechanisms of injury vary among the different age groups. Motor vehicle-related injuries, whether as vehicle occupants, bicyclists, or pedestrians, are the most common cause of pediatric blunt abdominal trauma.4 Child abuse is the leading cause of homicide in infants and may occur secondary to blunt abdominal injury. Other mechanisms of blunt abdominal trauma include falls, sports, and recreation-related injuries.

There are specific injury mechanisms that should lead the practitioner to suspect the presence of intra-abdominal injury,5 such as a handlebar injury (see Figure 1) to the upper abdomen and seat belt signs from a motor vehicle accident.

Management of intra-abdominal injury has undergone a major shift to non-operative management during the past decade. This shift to non-operative management has been possible due to the ability to accurately evaluate the abdomen and pelvis with computed tomography (CT) scan and ultrasound. Although most blunt injuries can be successfully managed non-operatively, the decision not to operate must be a thoughtful and rational decision. Early involvement of a surgeon experienced in the management of traumatic abdominal injuries in children is considered imperative.7

Pathophysiology

It must be remembered that children are not small adults. They have a unique anatomy, a different physiologic reserve, and a more pliant skeleton. As a result of unique anatomy and physiology, the injury patterns in children are different.8

Children’s intra-abdominal organs are more closely situated to each other, and the likelihood of multiple organs being injured is higher in pediatric blunt abdominal trauma. There is also less protective adipose tissue, connective tissue, and muscle mass. This results in the force of the blow transmitting more energy to internal organs and increasing the chance of intra-abdominal injury.9,10

The skeleton of a child is not completely calcified, which allows it to be more pliable. The consequence is that a child’s skeleton absorbs less energy from the trauma, and underlying organs may be injured even in the absence of bony injury. Alternatively, when there are bony injuries, this suggests that a great amount of force was applied, and the suspicion of intra-abdominal injury should be high.

Initial Management

The initial evaluation of any trauma patient is vital to a successful outcome. Every trauma patient, including pediatric patients of all ages, must be initially managed according to the principles of Advanced Trauma Life Support (ATLS).11

A primary survey needs to be completed without delay to identify immediately life-threatening injuries.12 The primary survey consists of an assessment of the airway to ensure that it is open to allow the travel of air into and out of the lungs without any hindrance.13

Vital signs in children vary according to age group, and the practitioner should be familiar with the range of normal vital signs in children. (See Table 1.)

Table 1. Vital Functions14
Age	Weight (kg)	Heart Rate (beats/min)	Blood Pressure (mmHg)	Respiratory Rate (breaths/min)	Urinary Output (mL/kg/hr)
0-12 months	0-10	< 160	> 60	< 60	2.0
1-2 years	10-14	< 150	> 70	< 40	1.5
3-5 years	14-18	< 140	> 75	< 35	1.0
6-12 years	18-36	< 120	> 80	< 30	1.0
> 13 years	36-70	< 100	> 90	< 30	0.5

Hypoxia is the most common cause of cardiac arrest in children, and bradycardia in children is a sign of hypoxia. Any child who cannot maintain his or her own airway, including those with severe head injury, significant hypovolemia, or in whom an operation is likely necessary, must be intubated.15

Spontaneous, effortless breathing should occur. A quick way to assess airway patency is to engage the patient in a conversation, and if patient is able to speak without difficulty, then the airway is likely intact. If there are clear breath sounds with easy flow of air, you can move on to checking for circulation.

Circulation is evaluated to ensure that there is no life-threatening bleeding. External bleeding is easily detected and controlled with manual compression. Internal bleeding may be more difficult to detect, but close attention to the patient’s vital signs and physical appearance can help in detecting occult bleeding. A child who is exhibiting signs of hypovolemia should alert the practitioner to the possibility of internal injuries and the need for resuscitation, as well as an investigation to find the source of bleeding.16

Finally, the primary survey should be completed with a quick neurologic examination, including Glasgow Coma Scale (GCS), and the patient must be disrobed from head to toe to allow for a complete and unhindered examination. Cover the child with warm blankets to prevent hypothermia once a thorough examination is complete.17

Adjuncts to the primary survey may include a chest X-ray, a pelvic X-ray, and the Focused Abdominal Sonography for Trauma (FAST) exam.

Chest X-ray

The chest X-ray in pediatric trauma is a valuable tool to identify conditions such as rib fractures, pneumothorax, hemothorax, and the rare aortic injury. It also serves as a screening tool to determine which patients need further imaging with a CT of the chest. A completely normal chest X-ray is associated with a reduced risk of having a significant thoracic injury and may allow the practitioner to safely avoid a CT of the chest.18

Routine pelvic X-rays in pediatric trauma patients are not necessary. A screening tool from the University of Michigan level 1 pediatric trauma center accurately predicts the absence of a pelvic fracture.¹⁹(See Table 2.)

Table 2. Risk Factors Predictive of Pelvic Fracture20
High-risk Clinical Findings GCS < 14 Positive urinalysis Pelvic tenderness Pelvic laceration Pelvic abrasion Abdominal pain/tenderness Femur fracture
High-risk Mechanism of Injury Unrestrained motor vehicle crash Motor vehicle crash with ejection Motor vehicle crash rollover Pedestrian struck by motor vehicle Bicyclist struck by motor vehicle

FAST Exam

The FAST exam has added a method to quickly evaluate a patient with possible abdominal injuries in the trauma bay. While FAST does not replace a CT scan in the evaluation of abdominal trauma, it can aid in the decision to perform a CT scan or go to the operating room.

A positive FAST in a hemodynamically unstable patient who is not responding to resuscitation is an indication to go to the operating room. A positive FAST in a hemodynamically stable patient should spur further evaluation with a CT scan.

A negative FAST exam in combination with a benign physical exam and normal levels of ALT/AST, amylase, and lipase can decrease the likelihood of a CT scan being necessary.21,22 However, it must be remembered that a negative FAST exam alone does not exclude hemoperitoneum or intra-abdominal injury,23 and repeated assessment is warranted to assess for a change in the patient’s clinical condition.

Secondary Survey

A secondary survey follows the primary survey once the practitioner is confident there is no immediate life-threatening injury and the patient’s vital signs are normal or responding appropriately to resuscitation.24

The secondary survey consists of a complete medical history, including medications, surgical history, last meal, and allergies. Additional tests in the secondary survey may include further radiographic imaging, such as a CT scan or additional X-rays and lab work.

In the evaluation of blunt abdominal trauma, a CBC, CMP, hepatic function panel, amylase, and lipase should be sent. Laboratory studies are sent to assist in the evaluation of the patient with blunt abdominal trauma based on organ system. Serial laboratory values are generally more helpful than any single value, but ALT and AST values greater than 250 U/L warrant further evaluation.

CT SCAN

CT scanning is the imaging study of choice for blunt abdominal trauma in children, but there is a downside to CT scans.25 Although CT is able to identify and evaluate intra-abdominal organ injury with great accuracy,26 children should not be unnecessarily or reflexively exposed to the radiation from a CT scan.27

Hemodynamically unstable patients do not belong in the CT scan under any circumstances. A trauma patient who is hemodynamically unstable belongs in the operating room if he or she is not responding to resuscitation.

While CT scans are being increasingly used to assess for traumatic injuries,28 there is concern for the eventual development of malignancy related to the radiation exposure from even one CT scan. One study shows that children with no evidence of abdominal wall trauma, no abdominal tenderness, a GCS greater than or equal to 14, no vomiting, no thoracic wall trauma, and normal breath sounds are at very low risk of an intra-abdominal injury and do not require CT scan to exclude injury.29

CT is beneficial when assessment must be made of an intubated trauma patient.30 Use of oral contrast is not indicated in a trauma setting. It leads to a delay in diagnosis and is a potential aspiration risk.

Diagnostic Peritoneal Lavage

Diagnostic peritoneal lavage (DPL) is rarely indicated in evaluation of pediatric trauma and, if performed, must be done by a surgeon. It has been largely replaced by the FAST exam. Because most solid organ injuries do not require surgical intervention, a positive DPL has limited clinical significance in the management of solid organ injuries.31 DPL does have the highest sensitivity in detection of bowel injury. The presence of bile, food particles, and amylase activity can be used to diagnose small bowel perforation.

Diagnostic Laparoscopy

Diagnostic laparoscopy can be both diagnostic and therapeutic in cases of bowel injury.32 Some trauma surgeons contend that a diagnostic laparoscopy is appropriate in the scenario of suspicion for a bowel injury instead of DPL because of the lower morbidity associated with diagnostic laparoscopy. It is also the test of choice for suspected diaphragmatic injury, although this is rare in pediatric trauma patients.

Resuscitation

The goal of initial resuscitation is to normalize vital signs and to maintain perfusion of vital organs.33 One pitfall to be aware of in pediatric trauma patients is that they are able to maintain a normal blood pressure despite significant volume loss. The initial physiologic response to blood loss will be tachycardia. Hypotension in children indicates a significant hypovolemia. (See Table 3.)

³⁴

System

< 30% blood loss

30-45% blood loss

> 45% blood loss

Cardiovascular

Increased heart rate, weak thready peripheral pulses, normal blood pressure (80-90 + 2 × age in years), normal pulse pressure

Markedly increased heart rate, thready central pulses, absent peripheral pulses, low normal systolic blood pressures (70-80 + 2 × age in years), narrowed pulse pressure

Tachycardia followed by bradycardia, very weak or absent central pulses, absent peripheral pulses, hypotension (< 70 + 2 × age in years), narrowed pulse pressure (or undetectable diastolic blood pressure)

Central nervous system

Anxious, irritable, confused

Lethargic, dulled response to pain

Comatose

Skin

Cool, mottled, prolonged capillary refill

Cyanotic, markedly increased capillary refill

Pale and cold

Urine output

Low to very low

Minimal

None

The initial bolus of intravenous fluid should be 20 mL/kg of a crystalloid solution, such as normal saline or lactated Ringers. If there is no response, a second bolus should be given. If hemodynamic instability remains, a third bolus of 20 mL/kg of a crystalloid solution can be given, but at this point there should be a consideration for using packed red blood cells.35,36 Transfusion protocols vary and are dependent on institution-based protocols.

Continuous monitoring of the patient response to the fluid boluses is imperative. Patients are characterized as either responders, non-responders, or transient responders.

Responders will have improved vital signs, a clearer mental status, return of normal skin color, increased perfusion of the extremities as indicated by peripheral pulses, and increased warmth of the skin.

Non-responders are those patients whose hemodynamic status does not respond to crystalloid or blood products. These patients must receive ongoing resuscitation and be taken to the operating room for control of hemorrhage.37

Hemodynamic instability should not delay surgical intervention because ongoing hypotension that is unresponsive to resuscitation increases mortality and morbidity. Prompt control of injuries is necessary.

Transient responders show preliminary improvement of their hemodynamic status, but the status worsens again over time. This likely indicates ongoing bleeding and requires ongoing resuscitation and consideration of surgical intervention. It is also possible that additional resuscitation will stabilize a patient and avoid the need for an operation.

Liver Injury

The liver accounts for nearly one-third of injured organs in pediatric blunt abdominal trauma, and most injuries are managed non-operatively as long as the patient remains hemodynamically stable and does not have other injuries (i.e., a bowel injury) that require operative intervention.

Liver injury should be suspected in patients with trauma to the right upper quadrant and those complaining of right upper quadrant pain. Severe liver trauma can cause significant internal bleeding that may need operative intervention. Patients with suspected liver injury who are unstable and not responding to resuscitation need to go to the operating room. These injuries have a high mortality, even with surgical intervention.

An active blush on CT scan may be successfully managed by embolization, but there is still debate over the safety of angioembolization in children.38 (See Figure 2.)

Non-operative management according to APSA guidelines have been successful in guiding care. They suggest bed rest equal to the grade of the injury plus one day, but protocols vary by institution. There are data to suggest an accelerated protocol of one night of bed rest for grade I and II injuries, and two nights for grade III or higher can be used without harm.39

Splenic Injury

The spleen is the most commonly injured organ in pediatric abdominal trauma. Non-operative management has become standard practice and achieves a high success rate.40 Splenic preservation should be achieved whenever possible to avoid post-splenectomy infection, which has a high mortality rate, and splenectomy has been shown to increase risk of infection and death.41,42

Splenic injury should be suspected in children with direct trauma to the left side, associated rib fractures, and left upper quadrant tenderness. CT scan is the standard imaging study to diagnose and grade a splenic injury. (See Figure 3.) CT also guides management of injuries, and a finding of blush on CT scan seems to increase the rate of operation and correlate with hemodynamic instability.43 However, even most of the patients with blush still can be managed successfully with non-operative management.44,45

Splenic angioembolization (SAE) can be used when the CT scan suggests ongoing bleeding, as long as the patient is hemodynamically stable. (See Figure 4.)

The decision to operate on a patient with a splenic injury is best based on hemodynamic stability, ongoing blood loss, and responsiveness to non-operative methods rather than grade of injury.

Observation with bed rest, serial physical examinations, and frequent hematocrit checks for management of splenic laceration according to APSA guidelines have been shown to be effective.^46,47Stylianos proposes that only grade IV injuries or above (see Table 4) should be observed in the intensive care unit (ICU) for one day, and that no follow-up imaging is indicated. Activity restriction should be based on grade of injury.48

Table 4. Spleen Injury Scale (1994 Revision)49
Grade*	Injury Type	Description of Injury
I	Hematoma Laceration	Subcapsular, < 10% surface area Capsular tear, < 1 cm parenchymal depth
II	Hematoma Laceration	Subcapsular, 10%-50% surface area Intraparenchymal, < 5 cm in diameter Capsular tear, 1-3 cm parenchymal depth that does not involve a trabecular vessel
III	Hematoma Laceration	Subcapsular, > 50% surface area or expanding; ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma > 5 cm or expanding > 3 cm parenchymal depth or involving trabecular vessels
IV	Laceration	Laceration involving segmental or hilar vessels producing major devascularization (> 25% of spleen)
V	Laceration Vascular	Completely shattered spleen Hilar vascular injury with devascularized spleen
*Advance one grade for multiple injuries up to grade III.

Injury to the Intestine

Detection of bowel injury poses a challenge to the clinician. Bowel injury is not always evident at initial presentation and may have a delayed presentation secondary to perforation. Mesenteric tears can cause associated bowel to become ischemic and present with perforation even days after the initial trauma. (See Figure 5.)

Intestinal injury should be considered with any patient who has suffered trauma to the abdomen, has any abdominal tenderness, or has visible abdominal wall ecchymosis. In particular, a seat belt sign should raise a clinician’s suspicion for a bowel injury.50 CT findings of extraluminal air, free intraperitoneal fluid, bowel wall thickening, bowel wall enhancement, bowel dilatation, and fat stranding should raise the clinician’s suspicion of a bowel injury and perforation. Although CT scan is very useful in diagnosing injuries, the findings on CT scan must be interpreted in the clinical context. Serial clinical examination is the gold standard for diagnosis of intestinal injury.51

Rapid deceleration, as in the case of a restrained passenger in a motor vehicle crash, can cause injury to the bowel near a point of fixation (i.e., ligament of Treitz, terminal ileum, and rectosigmoid region).

Initial and subsequent serial abdominal exams are more critical to the diagnosis of bowel injury than any imaging modality.52 If there is a perforation, early or late, an awake patient will have abdominal pain and signs of peritonitis due to the contents of the bowel irritating the peritoneum.

If a bowel injury is suspected, surgical consultation is mandatory.

Duodenal Injury

Duodenal injury is a specific type of injury to the intestines with unique characteristics. Due to the location of the duodenum in the protected retroperitoneum, duodenal injury is rare. Additionally, duodenal injuries may be associated with other injuries that can distract the clinician from making the diagnosis. There are reports that isolated duodenal injury is highly associated with child abuse.53 Therefore, the clinician’s suspicion of child abuse should rise when presented with a patient with isolated duodenal injury, as well as a history of trauma that does not correlate with the injuries.

Diagnosis of duodenal injury is difficult, but when suspicion for a duodenal injury exists, early CT scan with oral contrast will help make the diagnosis.54 Duodenal injuries can be categorized into different grades based on size of hematoma or perforation/laceration.

A duodenal hematoma is managed non-operatively, and perforation is managed with an operation.55 Non-operative management of hematoma is bowel rest with no oral intake and total parenteral nutrition. Resolution of the hematoma normally requires 1-3 weeks of observation and nutrition provided with TPN.

There are multiple operative managements of duodenal lacerations, and surgical consultation must be obtained in cases of duodenal perforation. All surgical treatments include drainage of the area. A variety of methods exist to bypass and repair the injury.56 However, each institution has a low number of experiences with operative duodenal injuries per year, and a definite best method of repair is not established.

Pancreatic Injury

Pancreatic injuries are rare in pediatric blunt abdominal trauma, with an estimated range from 3% to 12%. Detecting this rare injury requires a high degree of suspicion based on the mechanism of injury and early CT scan (see Figure 6) to prevent a delay in diagnosis and subsequent complications, such as infection.57

Pancreatic injury occurs most commonly from force applied to the abdomen that results in compression of the abdomen against the vertebra and crushes the pancreas in between two structures, such as a classic handlebar injury to the mid upper abdomen. The signs and symptoms are vague, which often leads to a delay in diagnosis.

The initial serum amylase may be normal, even with complete transection of the duct. A CT scan with IV contrast and serial measurements of amylase are helpful in making the diagnosis. If injury is still suspected, ERCP can provide early evaluation and the possibility of intervention with pancreatic injuries.

Treatment of pancreatic injury is not well defined, secondary to the rarity of this injury. Proponents of non-operative management point to safe management of pancreatic injury with no morbidity.58,59 The development of pseudocysts is expected in this patient population and can be managed with percutaneous drainage.60 Proponents of early intervention quote a higher rate of TPN dependency and an increase in complications with non-operative management.61

Higher-grade pancreatic injuries can be managed with ERCP. Laparoscopic pancreatectomies of the distal pancreas, when indicated, are possible.

Renal Trauma

The majority of cases of renal injury result from motor vehicle crashes, falls, and sports-related trauma.63 Like the other solid organ injuries from blunt abdominal trauma, renal injuries in a hemodynamically stable patient can be managed non-operatively.64

Renal injury should be suspected in patients with gross hematuria or microscopic hematuria with associated hypotension. Other findings associated with renal trauma include flank tenderness, a flank or abdominal mass, and ecchymosis of the flank.

In a hemodynamically stable patient, a CT scan with IV contrast should be obtained to grade the injury. Management should be based on the grade of the injury. Grade 1 to 3 injuries can be almost universally managed non-operatively. Grade 4 or 5 injuries can be selectively managed non-operatively if the patient is hemodynamically stable and has no associated abdominal injuries that require surgery.65,66

As long as the patient remains hemodynamically stable, bed rest and observation are indicated. If there is an active bleed seen on CT scan and the patient is hemodynamically stable, angiographic embolization can be used. Surgical intervention should be undertaken for hemodynamic instability or persistent blood loss requiring ongoing transfusions.67

If the patient is unstable, the operating room is the safest place. Prior to performing a nephrectomy on the injured kidney, the surgical team should ensure that the patient has two kidneys.

Aortic Injury

Blunt abdominal trauma causing abdominal aortic injury is exceedingly rare in the pediatric population. Since 1966, there have been only 17 reports in the literature of pediatric trauma patients with aortic injury from blunt trauma.68

Chance fractures associated with seat belts from motor vehicle crashes are a common mechanism.69 Other mechanisms include child abuse, horseback riding, and handlebar injuries from bicycle crashes.

The symptoms of abdominal aortic injury include nonspecific complaints of abdominal and back pain, as well as specific findings such as loss of distal pulses, pulsatile abdominal mass, abdominal bruit, and paraplegia.70

Diagnosis can be made with a CT scan, and treatment normally includes open operative repair. Endovascular techniques have been reported for thoracic aortic injuries in children, but disadvantages, such as stent migration as the patient grows, must be considered.

Child Abuse

Abdominal trauma is the second leading cause of abusive trauma mortality.71 The true incidence of abusive abdominal trauma is difficult to determine, but child abuse should be considered when a child presents with abdominal trauma and a discordant story. Risk factors include poverty, male gender, young age, previous unexplained or repetitive injuries, an adult male other than the father in the home, and children with physical and developmental delays.72

While any organ may be injured from abuse, the liver and the bowel are the most common, and injuries to multiple organs are not uncommon. Toddlers aged 2 to 4 years of age are the most likely to suffer abusive injuries, but infants and older children, including adolescents, are at risk, too.

A high level of suspicion should be maintained in children whose history and pattern of injuries do not correlate. Social work consults and referral to child protective services for investigation should be considered in suspected cases.

Summary

Adherence to the principles of ATLS is imperative in managing pediatric trauma effectively. A delay in diagnosis and treatment leads to an increased rate of complications. Advances in technology have made evaluation of intra-abdominal injuries increasingly less invasive, but clinical acumen and a high degree of suspicion is still the most important aspect of management.

The majority of blunt abdominal injuries to solid organs can be managed non-operatively, but surgical consultation should be obtained prior to committing this course of treatment. Serial examination and re-evaluation is mandatory while treating any injury non-operatively. Hollow organ injuries, such as bowel injuries, require operative intervention and should not be treated non-operatively.

The care of pediatric patients with blunt abdominal trauma can be challenging. Adhering to the principles of trauma resuscitation according the ATLS will help clinicians to recognize injuries early and lead to proper treatment. Transfer to institutions well versed in the care of pediatric patients should be considered, especially for those with multisystem trauma.73

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