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Blunt Abdominal Trauma
Background
The care of the trauma patient is demanding and requires speed and efficiency. Evaluating patients who
have sustained blunt abdominal trauma remains one of the most challenging and resource-intensive
aspects of acute trauma care.
Blunt abdominal trauma is a leading cause of morbidity and mortality among all age groups. Identification
of serious intra-abdominal pathology is often challenging. Many injuries may not manifest during the initial
assessment and treatment period. Missed intra-abdominal injuries and concealed hemorrhage are frequent
causes of increased morbidity and mortality, especially in patients who survive the initial phase after an
injury.
Physical examination findings are notoriously unreliable. One reason is that mechanisms of injury often
result in other associated injuries that may divert the physician’s attention from potentially life-threatening
intra-abdominal pathology. Other common reasons are an altered mental state and drug and alcohol
intoxication.
Coordinating a trauma resuscitation demands a thorough understanding of the pathophysiology of trauma
and shock, excellent clinical and diagnostic acumen, skill with complex procedures, compassion, and the
ability
to
think
rationally
in
a
chaotic
milieu.
Blunt abdominal trauma usually results from motor vehicle collisions (MVCs), assaults, recreational
accidents, or falls. The most commonly injured organs are the spleen, liver, retroperitoneum, small bowel,
kidneys, bladder, colorectum, diaphragm, and pancreas. Men tend to be affected slightly more often than
women.
Anatomy
The abdomen can be arbitrarily divided into 4 areas. The first is the intrathoracic abdomen, which is the
portion of the upper abdomen that lies beneath the rib cage. Its contents include the diaphragm, liver,
spleen, and stomach. The rib cage makes this area inaccessible to palpation and complete examination.
The second is the pelvic abdomen, which is defined by the bony pelvis. Its contents include the urinary
bladder, urethra, rectum, small intestine, and, in females, ovaries, fallopian tubes, and uterus. Injury to
these structures may be extraperitoneal in nature and therefore difficult to diagnose.
The third is the retroperitoneal abdomen, which contains the kidneys, ureters, pancreas, aorta, and vena
cava. Injuries to these structures are very difficult to diagnose on the basis of physical examination findings.
Evaluation of the structures in this region may require computed tomography (CT) scanning, angiography,
and intravenous pyelography (IVP).
The fourth is the true abdomen, which contains the small and large intestines, the uterus (if gravid), and the
bladder (when distended). Perforation of these organs is associated with significant physical findings and
usually manifests with pain and tenderness from peritonitis. Plain x-ray films are helpful if free air is present.
Additionally, diagnostic peritoneal lavage (DPL) is a useful adjunct.
Pathophysiology
Intra-abdominal injuries secondary to blunt force are attributed to collisions between the injured person and
the external environment and to acceleration or deceleration forces acting on the person’s internal organs.
Blunt force injuries to the abdomen can generally be explained by 3 mechanisms.
The first mechanism is deceleration. Rapid deceleration causes differential movement among adjacent
structures. As a result, shear forces are created and cause hollow, solid, visceral organs and vascular
pedicles to tear, especially at relatively fixed points of attachment. For example, the distal aorta is attached
to the thoracic spine and decelerates much more quickly than the relatively mobile aortic arch. As a result,
shear forces in the aorta may cause it to rupture. Similar situations can occur at the renal pedicles and at
the cervicothoracic junction of the spinal cord.
Classic deceleration injuries include hepatic tear along the ligamentum teres and intimal injuries to the renal
arteries. As bowel loops travel from their mesenteric attachments, thrombosis and mesenteric tears, with
resultant splanchnic vessel injuries, can result.
The second mechanism involves crushing. Intra-abdominal contents are crushed between the anterior
abdominal wall and the vertebral column or posterior thoracic cage. This produces a crushing effect, to
which solid viscera (eg, spleen, liver, kidneys) are especially vulnerable.
The third mechanism is external compression, whether from direct blows or from external compression
against a fixed object (eg, lap belt, spinal column). External compressive forces result in a sudden and
dramatic rise in intra-abdominal pressure and culminate in rupture of a hollow viscous organ (ie, in
accordance with the principles of Boyle law).
The liver and spleen seem to be the most frequently injured organs, though reports vary. The small and
large intestines are the next most frequently injured organs. Recent studies show an increased number of
hepatic injuries, perhaps reflecting increased use of CT scanning and concomitant identification of more
injuries.
Etiology
Vehicular trauma is by far the leading cause of blunt abdominal trauma in the civilian population. Auto-toauto and auto-to-pedestrian collisions have been cited as causes in 50-75% of cases. Other common
etiologies include falls and industrial or recreational accidents. Rare causes of blunt abdominal injuries
include iatrogenic trauma during cardiopulmonary resuscitation, manual thrusts to clear an airway, and the
Heimlich maneuver.
Epidemiology
United States statistics
By nearly every measure, injury ranks as one of the most pressing health issues in the United States. More
than 150,000 people die each year as a result of injuries, such as motor vehicle crashes, fires, falls,
drowning, poisoning, suicide, and homicide. Injuries are the leading cause of death and disability for US
children and young adults.
According to the 2000 statistics from the National Center for Injury Prevention and Control, trauma
(unintentional and intentional) was the leading cause of death in persons aged 1-44 years.
In 2001, approximately 30 million people visited emergency departments (EDs) for the treatment of nonfatal
injuries, and more than 72,000 people were disabled by injuries. Injury imposes exceptional costs, both in
health care dollars and in human losses, to society.
The true frequency of blunt abdominal trauma, however, is unknown. Data collected from trauma centers
reflect patients who are transported to or seek care at these centers; these data may not reflect patients
presenting to other facilities. The incidence of out-of-hospital deaths is unknown.
One review from the National Pediatric Trauma Registry by Cooper et al reported that 8% of patients
(total=25,301) had abdominal injuries. Eighty-three percent of those injuries were from blunt mechanisms.
Automobile-related injuries accounted for 59% of those injuries. Similar reviews from adult trauma
databases reflect that blunt trauma is the leading cause of intra-abdominal injury and that MVC is the
leading mode of injury. Blunt injuries account for approximately two thirds of all injuries.
Hollow viscus trauma is more frequent in the presence of an associated, severe, solid organ injury,
particularly to the pancreas. Approximately two thirds of patients with hollow viscus trauma are injured in
MVCs.
International statistics
In 1990, approximately 5 million people died worldwide as a result of injury. The risk of death from injury
varied strongly by region, age, and sex. Approximately 2 male deaths due to violence were reported for
every female death. Injuries accounted for approximately 12.5% of all male deaths, compared with 7.4% of
female deaths.
Globally, injury accounts for 10% of all deaths; however, injuries in sub-Saharan Africa are far more
destructive than in other areas.
Estimates indicate that by 2020, 8.4 million people will die yearly from injury, and injuries from traffic
collisions will be the third most common cause of disability worldwide and the second most common cause
in the developing world.
Most studies indicate that the peak incidence is in persons aged 14-30 years.
Sex-related differences in incidence
According to national and international data, blunt abdominal trauma is more common in men. The maleto-female ratio is 60:40.
Prognosis
Overall prognosis for patients who sustain blunt abdominal trauma is favorable. Without statistics that
indicate the number of out-of-hospital deaths and the total number of patients with blunt trauma to the
abdomen, a description of the specific prognosis for patients with intra-abdominal injuries is difficult.
Mortality rates for hospitalized patients are approximately 5-10%.
Patient Education
Proper adjustment of restraints in motor vehicles is an important aspect of patient education. The following
are key recommendations:
Wear lap belts in conjunction with shoulder restraints.
Adjust lap belts so that they fit snugly, and place them across the lower abdomen and below the iliac crests.
Wear restraints even in vehicles equipped with supplemental vehicle restraints (eg, airbags).
Adjust seats and steering wheels so that the distance between the abdominal wall and the steering wheel
is as wide as possible while still allowing proper control of the vehicle.
Advise patients to practice defensive driving by observing speed limits and keeping a safe distance between
them and other automobiles on the road.
History
Initially, evaluation and resuscitation of a trauma patient occur simultaneously. In general, do not obtain a
detailed history until life-threatening injuries have been identified and therapy has been initiated. The initial
assessment begins at the scene of the injury, with information provided by the patient, family, bystanders,
or paramedics, or police.
Important factors relevant to the care of a patient with blunt abdominal trauma, specifically those involving
motor vehicles, include the following:
The extent of vehicular damage
Whether prolonged extrication was required
Whether the passenger space was intruded
Whether a passenger died
Whether the person was ejected from the vehicle
The role of safety devices such as seat belts and airbags
The presence of alcohol or drug use
The presence of a head or spinal cord injury
Important elements of the pertinent history include the following:
Allergies
Medications
Past medical and surgical history
Time of last meal
Immunization status
Events leading to the incident
Social history, including history of substance abuse
Information from family and friends
The mnemonic AMPLE (A llergies, M edications, P ast medical history, L ast meal or other intake, and E
vents leading to presentation) is often useful as a means of remembering key elements of the history.
A history of out-of-hospital hypotension is a predictor of more significant intra-abdominal injuries. Even if
the patient is normotensive at arrival in the emergency department (ED), he or she should be considered
to be at increased risk.
Physical Examination
Primary survey
Resuscitation is performed concomitantly and continues as the physical examination is completed.
Priorities in resuscitation and diagnosis are established on the basis of hemodynamic stability and the
degree of injury. The goal of the primary survey, as directed by the Advanced Trauma Life Support (ATLS)
protocol, is to identify and expediently treat life-threatening injuries. The protocol includes the following:
Airway, with cervical spine precautions
Breathing
Circulation
Disability
Exposure
It is imperative for all personnel involved in the direct care of a trauma patient to exercise universal
precautions against body fluid exposure. The incidence of infectious diseases (eg, HIV, hepatitis) is
significantly higher in trauma patients than in the general public, with some centers reporting rates as high
as 19%. Even in medical centers with relatively low rates of communicable diseases, safely determining
who is infected with such pathogens is impossible.
The standard barrier precautions include a hat, eye shield, face mask, gown, gloves, and shoe covers.
Unannounced trauma arrival is probably the most common situation that leads to a breach in barrier
precautions. Personnel must be instructed to adhere to these guidelines at all times, even if it means a 30second delay in patient care.
Secondary survey
After an appropriate primary survey and initiation of resuscitation, attention should be focused on the
secondary survey of the abdomen. The secondary survey is the identification of all injuries via a head-totoe examination. For life-threatening injuries that necessitate emergency surgery, a comprehensive
secondary survey should be delayed until the patient has been stabilized.
At the other end of the spectrum are victims of blunt trauma who have a benign abdomen upon initial
presentation. Many injuries initially are occult and manifest over time. Frequent serial examinations, in
conjunction with the appropriate diagnostic studies, such as abdominal computed tomography (CT) and
bedside ultrasonography, are essential in any patient with a significant mechanism of injury.
The evaluation of a patient with blunt abdominal trauma must be accomplished with the entire patient in
mind, with all injuries prioritized accordingly. This implies that injuries involving the head, the respiratory
system, or the cardiovascular system may take precedence over an abdominal injury.
The abdomen should neither be ignored nor be the sole focus of the treating clinician and surgeon. In an
unstable patient, the question of abdominal involvement must be expediently addressed. This is
accomplished by identifying free intra-abdominal fluid with diagnostic peritoneal lavage (DPL) or focused
assessment with sonography for trauma (FAST). The objective is rapid identification of those patients who
need a laparotomy.
The initial clinical assessment of patients with blunt abdominal trauma is often difficult and notably
inaccurate. Associated injuries often cause tenderness and spasms in the abdominal wall and make
diagnosis difficult. Lower rib fractures, pelvic fractures, and abdominal wall contusions may mimic the signs
of peritonitis. In a collected series of 955 patients, Powell et al reported that clinical evaluation alone has
an accuracy rate of only 65% for detecting the presence or absence of intraperitoneal blood.
In general, accuracy increases if the patient is reevaluated repeatedly and at frequent intervals. However,
repeated examinations may not be feasible in patients who need general anesthesia and surgery for other
injuries. The greatest compromise of the physical examination occurs in the setting of neurologic
dysfunction, which may be caused by head injury or substance abuse.
The most reliable signs and symptoms in alert patients are pain, tenderness, gastrointestinal hemorrhage,
hypovolemia, and evidence of peritoneal irritation. However, large amounts of blood can accumulate in the
peritoneal and pelvic cavities without any significant or early changes in the physical examination findings.
Bradycardia may indicate the presence of free intraperitoneal blood in a patient with blunt abdominal
injuries.
The respiratory pattern should be observed because abdominal breathing may indicate spinal cord injury.
A sensory examination of the chest and abdomen should be performed to evaluate the potential for spinal
cord injury. Spinal cord injury may interfere with the accurate assessment of the abdomen by causing
decreased or absent pain perception.
The abdominal examination must be systematic. The abdomen is inspected for abrasions or ecchymosis.
Particular attention should be paid to injury patterns that predict the potential for intra-abdominal trauma
(eg, lap belt abrasions, steering wheel–shaped contusions). In most studies, lap belt marks have been
correlated with rupture of the small intestine and an increased incidence of other intra-abdominal injuries.
Ecchymosis involving the flanks (Grey Turner sign) or the umbilicus (Cullen sign) indicates retroperitoneal
hemorrhage, but this is usually delayed for several hours to days.
Visual inspection for abdominal distention, which may be due to pneumoperitoneum, gastric dilatation
secondary to assisted ventilation or swallowing of air, or ileus produced by peritoneal irritation, is important.
Auscultation of bowel sounds in the thorax may indicate the presence of a diaphragmatic injury. Abdominal
bruit may indicate underlying vascular disease or traumatic arteriovenous fistula.
Palpation may reveal local or generalized tenderness, guarding, rigidity, or rebound tenderness, which
suggests peritoneal injury. Such signs appearing soon after an injury suggest leakage of intestinal content.
Peritonitis due to intra-abdominal hemorrhage may take several hours to develop.
Fullness and doughy consistency on palpation may indicate intra-abdominal hemorrhage. Crepitation or
instability of the lower thoracic cage indicates the potential for splenic or hepatic injuries associated with
lower rib injuries.
Tenderness on percussion constitutes a peritoneal sign. Tenderness mandates further evaluation and
probably surgical consultation.
Rectal and bimanual vaginal pelvic examinations should be performed. A rectal examination should be
done to search for evidence of bony penetration resulting from a pelvic fracture, and the stool should be
evaluated for gross or occult blood. The evaluation of rectal tone is important for determining the patient’s
neurologic status, and palpation of a high-riding prostate suggests urethral injury.
The genitals and perineum should be examined for soft tissue injuries, bleeding, and hematoma. Pelvic
instability indicates the potential for lower urinary tract injury, as well as pelvic and retroperitoneal
hematoma. Open pelvic fractures are associated with a mortality rate exceeding 50%.
A nasogastric tube should be placed routinely (in the absence of contraindications, eg, basilar skull fracture)
to decompress the stomach and to assess for the presence of blood. If the patient has evidence of a
maxillofacial injury, an orogastric tube is preferred.
As the assessment continues, a Foley catheter is placed and a sample of urine is sent for analysis for
microscopic hematuria. If injury to the urethra or bladder is suggested because of an associated pelvic
fracture, then a retrograde urethrogram is performed before catheterization.
Tertiary survey
The concept of the tertiary trauma survey was first introduced by Enderson et al to assist in the diagnosis
of any injuries that may have been missed during the primary and secondary surveys. The tertiary survey
involves a repetition of the primary and secondary surveys and a revision of all laboratory and radiographic
studies. In 1 study, a tertiary trauma survey detected 56% of injuries missed during the initial assessment
within 24 hours of admission.
Approach Considerations
In recent years, laboratory evaluation of trauma patients has been a matter of significant discussion.
Commonly recommended studies include serum glucose, complete blood count (CBC), serum chemistries,
serum amylase, urinalysis, coagulation studies, blood typing and cross-matching, arterial blood gases
(ABGs), blood ethanol, urine drug screens, and a urine pregnancy test (for females of childbearing age).
Serum electrolyte values, creatinine level, and glucose values are often obtained for reference, but typically
they have little or no value in the initial management period.
Aggressive radiographic and surgical investigation is indicated in patients with persistent hyperamylasemia
or hyperlipasemia, conditions that suggest significant intra-abdominal injury.
All patients should have their tetanus immunization history reviewed. If it is not current, prophylaxis should
be given.
The most important initial concern in the evaluation of a patient with blunt abdominal trauma is an
assessment of hemodynamic stability. In the hemodynamically unstable patient, a rapid evaluation must be
made regarding the presence of hemoperitoneum. This can be accomplished by means of diagnostic
peritoneal lavage (DPL) or the focused assessment with sonography for trauma (FAST). Radiographic
studies of the abdomen are indicated in stable patients when the physical examination findings are
inconclusive.
Blood Studies
Complete blood count
The presence of massive hemorrhage is usually obvious from hemodynamic parameters, and an abnormal
hematocrit value merely confirms the diagnosis. Normal hemoglobin and hematocrit results do not rule out
significant hemorrhage. Patients bleed whole blood. Until blood volume is replaced with crystalloid solution
or hormonal effects (eg, adrenocorticotropic hormone [ACTH], aldosterone, antidiuretic hormone [ADH])
and transcapillary refill occurs, anemia may not develop.
Bedside diagnostic testing with rapid hemoglobin or hematocrit machines may quickly identify patients who
have physiologically significant volume deficits and hemodilution. Reported hemoglobin from ABG
measurements also may be useful in identifying anemia. Some studies have correlated a low initial
hematocrit (ie, < 30%) with significant injuries.
Do not withhold transfusion in patients who have relatively normal hematocrit results (ie, >30%) but have
evidence of clinical shock, serious injuries (eg, open-book pelvic fracture), or significant ongoing blood loss.
Hemodynamic instability in an adult despite the administration of 2 L of fluid indicates ongoing blood loss
and is an indication for immediate blood transfusion. Use platelet transfusions to treat patients with
thrombocytopenia (ie, platelet count < 50,000/µL) and ongoing hemorrhage.
An elevated white blood cell (WBC) count on admission is nonspecific and does not predict the presence
of a hollow viscus injury (HVI). The diagnostic value of serial WBC counts for predicting HVI within the first
24 hours after trauma is very limited.
Serum electrolyte measurements
Recently, the usefulness of routine serum chemistries of trauma patients has been questioned. Most trauma
victims are younger than 40 years and rarely are taking medications that may alter electrolytes (eg,
diuretics, potassium replacements).
The more prudent choice when attempting to limit cost involves selective ordering of these studies.
Selection should be based on the patient’s medications, the presence of concurrent nausea or vomiting,
the presence of dysrhythmias, or a history of renal failure or other chronic medical problems associated
with electrolyte imbalance.
Serum glucose and carbon dioxide measurements
If blood gas measurements are not routinely obtained, serum chemistries that measure serum glucose and
carbon dioxide levels are indicated. Rapid bedside blood-glucose determination, obtained with a fingerstick measuring device, is important for patients with altered mental status.
Liver function tests
Liver function tests (LFTs) may be useful in the patient with blunt abdominal trauma; however, test findings
may be elevated for several reasons (eg, alcohol abuse). One study has shown that an aspartate
aminotransferase (AST) or alanine aminotransferase (ALT) level more than 130 U corresponds with
significant hepatic injury. Lactate dehydrogenase (LDH) and bilirubin levels are not specific indicators of
hepatic trauma.
Serum amylase or lipase measurements
The serum lipase or amylase level is neither sensitive nor specific as a marker for major pancreatic or
enteric injury. Normal levels do not exclude a major pancreatic injury. Elevated levels may be caused by
injuries to the head and face or by an assortment of nontraumatic causes (eg, alcohol, narcotics, various
other drugs). Amylase or lipase levels may be elevated because of pancreatic ischemia caused by the
systemic hypotension that accompanies trauma.
However, persistent hyperamylasemia or hyperlipasemia (eg, abnormal elevation 3-6 hours after trauma)
should raise the suggestion of significant intra-abdominal injury and is an indication for aggressive
radiographic and surgical investigation.
Coagulation profile
The cost-effectiveness of routine prothrombin time (PT)/activated partial thromboplastin time (aPTT)
determination upon admission is questionable. PT or aPTT should be measured in patients who have a
history of blood dyscrasias (eg, hemophilia), who have synthetic problems (eg, cirrhosis), or who take
anticoagulant medications (eg, warfarin, heparin).
Blood typing, screening, and cross-matching
Blood from all trauma patients with suspected blunt abdominal injury should be screened and typed. If an
injury is identified, this practice greatly reduces the time required for cross-matching. An initial cross-match
should be performed on a minimum of 4-6 units for those patients with clear evidence of abdominal injury
and hemodynamic instability. Until cross-matched blood is available, O-negative or type-specific blood
should be used.
Arterial blood gas measurements
ABG values may provide important information in major trauma victims. In addition to information about
oxygenation (eg, partial pressure of oxygen [PO2] and arterial oxygen saturation [SaO2]) and ventilation
(partial pressure of carbon dioxide [PCO2]), this test provides valuable information regarding oxygen
delivery through calculation of the alveolar-arterial (A-a) gradient. ABG determinations also report total
hemoglobin more rapidly than CBCs.
Upon initial hospital admission, suspect metabolic acidemia to result from the lactic acidosis that
accompanies shock. A moderate base deficit (ie, more than –5 mEq) indicates the need for aggressive
resuscitation and determination of the etiology.
Attempt to improve systemic oxygen delivery by ensuring an adequate SaO2 (ie, >90%) and by acquiring
volume resuscitation with crystalloid solutions and, if indicated, blood.
Drug and alcohol screening
Perform drug and alcohol screens on trauma patients who have alterations in their level of consciousness.
Breath or blood testing may quantify alcohol level.
Urine Studies
Indications for diagnostic urinalysis include significant trauma to the abdomen and/or flank, gross
hematuria, microscopic hematuria in the setting of hypotension, and a significant deceleration mechanism.
Obtain a contrast nephrogram by utilizing intravenous pyelography (IVP) or computed tomography (CT)
scanning with intravenous (IV) contrast. Gross hematuria indicates a workup that includes cystography and
IVP
or
CT
scanning
of
the
abdomen
with
contrast.
Perform a urine toxicologic screen as appropriate. Obtain a serum or urine pregnancy test on all females
of childbearing age.
Plain Radiography
Although their overall value in the evaluation of patients with blunt abdominal trauma is limited, plain films
can demonstrate numerous findings. The chest radiograph may aid in the diagnosis of abdominal injuries
such as ruptured hemidiaphragm (eg, a nasogastric tube seen in the chest) or pneumoperitoneum.
The pelvic or chest radiograph can demonstrate fractures of the thoracolumbar spine. The presence of
transverse fractures of the vertebral bodies (ie, Chance fractures) suggests a higher likelihood of blunt
injuries to the bowel. In addition, free intraperitoneal air, or trapped retroperitoneal air from duodenal
perforation, may be seen.
Ultrasonography
The use of diagnostic ultrasonography to evaluate a patient with blunt trauma for abdominal injuries has
been advocated since the 1970s. European and Asian investigators have extensive experience with this
technology and are leaders in the use of ultrasound for the diagnosis of blunt abdominal trauma.
The first American report of physician-performed abdominal ultrasonography in the evaluation of blunt
abdominal trauma wa...
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