Abdominal Trauma, Blunt
John Udeani, MD, FAAEM, Assistant Professor, Department of Emergency Medicine, Charles Drew University of Medicine and Science, University of California, Los Angeles, David Geffen School of Medicine
Sidney R Steinberg, MD, FACS, Program Director, Department of General Surgery, Spartanburg Regional Healthcare System; Consulting Surgeon, Department of Surgery, WG Hefner Veterans Affairs Medical Center
Updated: Aug 22, 2008
Introduction
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.
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 for several reasons; a few examples are the presence of distracting injuries, an altered mental state, and drug and alcohol intoxication in the patient.
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, 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.
Frequency
United States
By nearly every measure, injury ranks as one of this nation's most pressing health issues. 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. Further review of the data reveals that in those aged 15-25 years, 14,113 persons died from unintentional injuries, 73% of which were related to vehicular trauma. In individuals aged 25-34 years, 57% of the 11,769 deaths reported were from motor vehicle collisions.
In 2001, approximately 30 million people visited emergency departments 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.
International
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. In sub-Saharan Africa, the risk of death from trauma is highest in those aged 15-60 years, and the proportion of such deaths from trauma is higher than in any other region of the world. In South Africa, for instance, the traffic death rate per unit of distance traveled is only surpassed by Korea, Kenya, and Morocco.
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.
Pathophysiology
Vehicular trauma is by far the leading cause of blunt abdominal trauma in the civilian population. Auto-to-auto and auto-to-pedestrian collisions have been cited as causes in 50-75% of cases. Rare causes of blunt abdominal injuries include iatrogenic trauma during cardiopulmonary resuscitation, manual thrusts to clear an airway, and the Heimlich maneuver.
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 is when 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.
The second is when 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 is external compression forces that 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).
Presentation
History
The initial assessment of a trauma patient begins at the scene of the injury, with information provided by the patient, family, bystanders, or paramedics. 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
Whether psychiatric problems were evident
Priorities in resuscitation and diagnosis are established based on hemodynamic stability and the degree of injury. The goal of the primary survey, as directed by the Advanced Trauma Life Support protocol, is to identify and expediently treat life-threatening injuries. The protocol includes the following:
Airway, with cervical spine precautions
Breathing
Circulation
Disability
Exposure
Key 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
Resuscitation is performed concomitantly and continues as the physical examination is completed. The secondary survey is the identification of all injuries via a head-to-toe examination.
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 30-second delay in patient care.
Physical examination
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 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 using diagnostic peritoneal lavage (DPL) or the Focused Assessment with Sonography for Trauma (FAST) examination. The objective is to rapidly identify 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.1 In general, accuracy increases if the patient is examined 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.
The abdominal examination must be systematic. The abdomen is inspected for abrasions or ecchymosis. The seat belt sign, ie, a contusion or abrasion across the lower abdomen, is highly correlated with intraperitoneal pathology. Visual inspection for abdominal distention, which may be due to pneumoperitoneum, gastric dilatation, or ileus produced by peritoneal irritation, is important. 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. Rib fractures involving the lower chest may be associated with splenic or liver injuries. Auscultation of bowel sounds in the thorax may indicate the presence of a diaphragmatic injury. Palpation may reveal local or generalized tenderness, guarding, rigidity, or rebound tenderness, which suggests peritoneal injury.
A rectal examination should be performed 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.
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.
Because of the wide spectrum of injuries, frequent reevaluation is an essential component in the management of patients with blunt abdominal trauma.
Pediatric patients are assessed and treated at least initially as adults with respect to the primary and secondary surveys. However, obvious anatomical and clinical differences exist and these must be kept in mind: the child's physiologic response to injury is different; communication is not always possible; physical examination findings become more important; the pediatric patient's blood volume is less, predisposing them to rapid exsanguination; technical procedures tend to be more time consuming and challenging; and a child's relatively large body surface area contributes to rapid heat loss. Perhaps, the most significant difference between pediatric and adult blunt trauma is that, for the most part, pediatric patients can be resuscitated and treated nonoperatively. Some pediatric surgeons often transfuse up to 40 mL/kg of blood products in an effort to stabilize a pediatric patient. Obviously, if this fails and the child continues to be unstable, laparotomy is indicated.
Tertiary examination
This concept 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.2 The tertiary survey involves a repetition of the primary and secondary surveys and a revision of all laboratory and radiographic studies. In one study, a tertiary trauma survey detected 56% of injuries missed during the initial assessment within 24 hours of admission.
Indications
Aggressive radiographic and surgical investigation is indicated in patients with persistent hyperamylasemia or hyperlipasemia, conditions that suggest significant intra-abdominal injury.
Stable patients with inconclusive physical examination findings should undergo radiographic studies of the abdomen.
DPL is indicated in blunt trauma as follows:
Patients with a spinal cord injury
Those with multiple injuries and unexplained shock
Obtunded patients with a possible abdominal injury
Intoxicated patients in whom abdominal injury is suggested
Patients with potential intra-abdominal injury who will undergo prolonged anesthesia for another procedure
An indication for immediate blood transfusion is hemodynamic instability despite the administration of 2 L of fluid to adult patients; this instability indicates ongoing blood loss.
Indications for laparotomy in a patient with blunt abdominal injury include the following:
Signs of peritonitis
Uncontrolled shock or hemorrhage
Clinical deterioration during observation
Hemoperitoneum findings after FAST or DPL examinations
Finally, surgical intervention is indicated in patients with evidence of peritonitis based on physical examination findings.
Relevant 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 for 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, the 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 based on physical examination findings. Evaluation of the structures in this region may require a CT scan, angiography, and an intravenous pyelogram.
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, DPL is a useful adjunct.
Contraindications
While not a contraindication to surgical repair, the evaluation of a patient with blunt abdominal trauma must be prioritized based on the most urgent problems. This implies that injuries involving the head, the respiratory system, or the cardiovascular system may take precedence over an abdominal injury.
Although a nasogastric tube is routine in order to decompress the stomach and assess for the presence of blood, it is contraindicated in patients with basilar skull fracture. An orogastric tube is preferred if the patient has evidence of a maxillofacial injury.
Operative treatment is not indicated in every patient with positive FAST scan results. Hemodynamically stable patients with positive FAST findings may require a CT scan to better define the nature and extent of their injuries. Operating on every patient with positive FAST scan findings may result in an unacceptably high laparotomy rate.
The only absolute contraindication to DPL is the obvious need for laparotomy. Relative contraindications include morbid obesity, a history of multiple abdominal surgeries, and pregnancy.
Resuscitative thoracotomy is not recommended in patients with blunt thoracoabdominal trauma who have pulseless electrical activity upon arrival in the emergency department. The survival rate in this situation is virtually 0%. These patients may be allowed a thoracotomy in the emergency department only if they have signs of life upon arrival to the emergency department.
Workup
Laboratory Studies
Valuable blood studies in the initial evaluation of a patient with blunt abdominal trauma vary by institution but should include a CBC count, coagulation studies, blood type, and blood cross-match (if indicated). The presence of massive hemorrhage is usually obvious from hemodynamic parameters, and the hematocrit value merely confirms the diagnosis.
Urine studies include urinalysis, urine toxicologic screen, and serum or urine pregnancy tests in females of appropriate 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.
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 should raise the suggestion of significant intra-abdominal injury and is an indication for aggressive radiographic and surgical investigation.
All patients should have their tetanus immunization history reviewed. If it is not current, prophylaxis should be given.
Imaging Studies
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 using DPL or the FAST scan. Radiographic studies of the abdomen are indicated in stable patients when the physical examination findings are inconclusive.
Plain radiograph
Although the overall value of plain films in the evaluation of patients with blunt abdominal trauma is limited, they 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.
Ultrasound
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 ultrasound in the evaluation of blunt abdominal trauma was published in 1992 by Tso and colleagues.3 Since then, numerous articles have been published in the United States advocating the use of ultrasound in the evaluation of the patient with blunt abdominal trauma.
Bedside ultrasonography is a rapid, portable, noninvasive, and accurate examination that can be performed by emergency clinicians and trauma surgeons to detect hemoperitoneum. In fact, in many medical centers, the FAST examination has virtually replaced DPL as the procedure of choice in the evaluation of hemodynamically unstable trauma patients.
An examination is interpreted as positive if fluid is found in any of the 4 acoustic windows and is interpreted as negative if no fluid is seen. An examination is deemed indeterminate if any of the windows cannot be adequately assessed.
In 1996, the examination was first termed Focused Abdominal Sonography for Trauma. However, in 1997, the FAST Consensus Conference Committee concluded that the acronym should stand for Focused Assessment with Sonography for Trauma. That same year, the American College of Surgeons included the use of ultrasound in the Advanced Trauma Life Support secondary survey.
The FAST examination is based on the assumption that all clinically significant abdominal injuries are associated with hemoperitoneum. However, the detection of free intraperitoneal fluid is based on factors such as the body habitus, injury location, presence of clotted blood, position of the patient, and amount of free fluid present.
The minimum threshold for detecting hemoperitoneum is unknown and remains a subject of interest. Kawaguchi and colleagues found that 70 mL of blood could be detected,4 while Tiling et al found that 30 mL is the minimum requirement for detection with ultrasound.5 They also concluded that a small anechoic stripe in the Morison pouch represents approximately 250 mL of fluid, while 0.5-cm and 1-cm stripes represent approximately 500 mL and 1 L of free fluid, respectively.
The current examination protocol consists of 4 acoustic windows with the patient supine. These windows are pericardiac, perihepatic, perisplenic, and pelvic (known as the 4 Ps).
The pericardial view is obtained using a subcostal or transthoracic window. It provides a 4-chamber view of the heart and can detect the presence of hemopericardium, which is demonstrated by the separation of the visceral and parietal pericardial layers. The perihepatic view images portions of the liver, diaphragm, and right kidney. It reveals fluid in the Morison pouch, the subphrenic space, and the right pleural space. The perisplenic view provides views of the spleen and the left kidney and reveals fluid in the splenorenal recess, the left pleural space, and the subphrenic space. The pelvic view uses the bladder as a sonographic window. This view is best accomplished while the patient has a full bladder. In males, free fluid is seen as an anechoic area (sonographically black) in the rectovesicular pouch or cephalad to the bladder. In females, fluid accumulates in the Douglas pouch, posterior to the uterus.
Reported sensitivities and negative predictive values for ultrasound in the detection of hemoperitoneum are 78-99% and 93-99%, respectively.
FAST examination relies on hemoperitoneum to identify patients with injury. Chiu and colleagues, in their study of 772 patients with blunt trauma undergoing FAST scans, reported 52 patients had an abdominal injury.6 Of the 52 patients, 15 (29%) had no hemoperitoneum on FAST or CT scan results. Hence, the reliance of hemoperitoneum as the sole indicator of abdominal visceral injury limits the utility of FAST as a diagnostic screening tool in stable patients with blunt abdominal trauma.
Rozycki et al studied 1540 patients and reported that ultrasound was the most sensitive and specific modality for the evaluation of hypotensive patients with blunt abdominal trauma (sensitivity and specificity, 100%).7
Hemodynamically stable patients with positive FAST results may require a CT scan to better define the nature and extent of their injuries. Taking every patient with a positive FAST result to the operating room may result in an unacceptably high laparotomy rate.
Hemodynamically stable patients with negative FAST results require close observation, serial abdominal examinations, and a follow-up FAST examination. However, strongly consider performing a CT scan, especially if the patient is intoxicated or has other associated injuries.
Hemodynamically unstable patients with negative FAST results are a diagnostic challenge. Options include DPL, exploratory laparotomy, and, possibly, a CT scan after aggressive resuscitation.
Computed tomography
The CT scan remains the criterion standard for the detection of solid organ injuries. In addition, a CT scan of the abdomen can reveal other associated injuries, notably vertebral and pelvic fractures and injuries in the thoracic cavity.
CT scans, unlike DPL or FAST examinations, have the capability to determine the source of hemorrhage. In addition, many retroperitoneal injuries go unnoticed with DPL and FAST examinations.
CT scans provide excellent imaging of the pancreas, duodenum, and genitourinary system. The images can help quantitate the amount of blood in the abdomen and can reveal individual organs with precision.
Limitations of CT scans include marginal sensitivity for diagnosing diaphragmatic, pancreatic, and hollow viscus injuries. Also, they are relatively expensive and time consuming and require oral or intravenous contrast, which may cause adverse reactions.
Other Tests
Laparoscopy
The introduction of minimally invasive surgery has revolutionized many surgical diagnostic protocols. In the late 1980s and early 1990s, considerable interest was garnered for the use of laparoscopy in the evaluation and management of blunt and penetrating abdominal trauma. However, subsequent studies revealed major limitations and cautioned against its widespread use. The most important limitation is its inability to reliably identify hollow viscus and retroperitoneal injuries, even in the hands of experienced laparoscopists
The procedure involves placing a subumbilical or subcostal trocar for the introduction of the laparoscope and creating other ports for retractors, clamps, and other tools necessary for visualization of the repair.
Diagnostic laparoscopy has been most useful in the evaluation of possible diaphragmatic injuries, especially in penetrating thoracoabdominal injuries on the left side.
In blunt trauma, diagnostic laparoscopy offers no clear advantage over less invasive modalities such as DPL or CT scan and complications can occur from trocar misplacement.
Diagnostic Procedures
Diagnostic peritoneal lavage
The idea of evaluating the abdomen by analyzing its contents was first used in the diagnosis of acute abdominal conditions. The principle was described by Salomon in 1906. He described the passage of a urethral catheter by means of a trocar inserted through the abdominal wall to obtain samples of peritoneal fluid to establish the diagnosis of peritonitis from infectious agents (eg, pneumococcal or tuberculous organisms). This technique has since been refined and is now known as abdominal paracentesis. In 1926, Neuhof and Cohen described the sampling of peritoneal fluid in cases of acute pancreatitis and blunt abdominal trauma by passing a spinal needle through the abdominal wall.8 In 1965, Root et al reported the use of diagnostic percutaneous peritoneal lavage in patients after blunt abdominal trauma.9
DPL is indicated in blunt trauma in (1) patients with a spinal cord injury, (2) those with multiple injuries and unexplained shock, (3) obtunded patients with a possible abdominal injury, (4) intoxicated patients in whom abdominal injury is suggested, and (5) patients with potential intra-abdominal injury who will undergo prolonged anesthesia for another procedure.
The only absolute contraindication to DPL is the obvious need for laparotomy. Relative contraindications include morbid obesity, a history of multiple abdominal surgeries, and pregnancy.
Various methods of introducing the catheter into the peritoneal space have been described. These include the open, semiopen, and closed methods. The open method requires an infraumbilical skin incision that is extended to and through the linea alba. The peritoneum is opened, and the catheter is inserted under direct visualization. The semiopen method is identical except the peritoneum is not opened and the catheter is delivered percutaneously through the peritoneum into the peritoneal cavity. The closed technique requires the catheter to be inserted blindly through the skin, subcutaneous tissue, linea alba, and peritoneum. The closed and semiopen techniques at the infraumbilical site are preferred at most centers. The fully open method is the most technically demanding and is restricted to those situations in which the closed or semiopen technique is unsuccessful or is deemed unsafe (eg, patients with pelvic fractures, pregnancy, obesity, or prior abdominal operations).
DPL results are considered positive in a blunt trauma patient if 10 mL of grossly bloody aspirate is obtained before infusion of the lavage fluid or if the siphoned lavage fluid (ie, 1 L normal saline infused into the peritoneal cavity via a catheter and allowed to mix, which is then drained by gravity) has more than 100,000 RBC/mL, more than 500 WBC/mL, elevated amylase content, bile, bacteria, vegetable matter, or urine. Only approximately 30 mL of blood is needed in the peritoneum to produce a microscopically positive DPL result.
DPL has been shown in some studies to have diagnostic accuracy of 98-100%, sensitivity of 98-100%, and specificity of 90-96%. It has some advantages, including high sensitivity, rapidity, and immediate interpretation. Its limitations include iatrogenic abdominal injury and its high sensitivity, which can lead to nontherapeutic laparotomies. False-positive DPL results can occur if an infraumbilical approach is used in a patient with a pelvic fracture. A pelvic x-ray film should be obtained prior to performing DPL if a pelvic fracture is suggested. Before DPL is attempted, the urinary bladder and stomach should be decompressed.
With the availability of fast, noninvasive, and better imaging modalities (eg, FAST examination, CT scan), the role of DPL is now limited to the evaluation of unstable trauma patients in whom FAST results are negative or inconclusive.
Treatment
Medical Therapy
The initial goal of paramedics with Advanced Trauma Life Support training is to rapidly assess the patient's airway with cervical spine precautions, breathing, and circulation. This is then followed by splinting of fractures and control of external hemorrhage. The injured patient is at risk for progressive deterioration from continued bleeding and requires rapid transport to a trauma center or the closest and most appropriate facility, with appropriate stabilization procedures performed en route. Hence, securing the airway, placing large-bore intravenous lines, and administering intravenous fluid must take place en route, unless delays in transport occur, for instance, if prolonged extrication is required.
Upon arrival at the emergency department or trauma center, the first priority is reassessment of the airway. Protection of the cervical spine with in-line immobilization is absolutely mandatory. If intubation is indicated, attempt nasotracheal (ie, if no contraindications) or endotracheal intubation. If unsuccessful, perform cricothyroidotomy. After an airway has been established, adequate ventilatory exchange is assessed by auscultation of both lung fields. Clinical diagnosis of a tension pneumothorax is treated with needle decompression followed by chest thoracostomy tube placement. Other mechanical factors that can interfere with ventilation include sucking chest wounds, a hemothorax, and pulmonary contusion. Treat these aggressively and expediently.
The next priority in the primary survey is an assessment of the circulatory status of the patient. Circulatory collapse in a patient with blunt abdominal trauma is usually caused by hypovolemia from hemorrhage. Effective volume resuscitation is accomplished by controlling external hemorrhage and infusing warmed crystalloid solution via 2 large-bore peripheral intravenous lines. Hemodynamic instability despite the administration of 2 L of fluid to adult patients indicates ongoing blood loss and is an indication for immediate blood transfusion. Administer type O, Rh-negative blood if cross-matched or type-specific blood is not available.
The primary survey is completed with a brief neurologic assessment of the patient using elements of the Glasgow Coma Scale. The patient is undressed and draped in clean, dry, warm sheets.
The secondary survey consists of a complete and thorough physical examination as indicated under Physical examination in the Clinical section.
Nonoperative management of blunt abdominal trauma
Nonoperative management strategies based on CT scan diagnosis and the hemodynamic stability of the patient are now being used in the treatment of adult solid organ injury, primarily the liver and spleen. In blunt abdominal trauma, including severe solid organ injuries, selective nonoperative management has become the standard of care.
Angiography is a valuable modality in the nonoperative management of adult abdominal solid organ injuries from blunt trauma. It is used aggressively for nonoperative control of hemorrhage, thus avoiding nontherapeutic cost-inefficient laparotomies.
Surgical Therapy
Resuscitative thoracotomy in the emergency department is only occasionally life-saving. It is an aggressive, desperate measure to save a patient in whom death is thought to be imminent or otherwise inevitable. Survival with good neurologic recovery is more likely for patients with penetrating trauma than for patients with blunt trauma. Thoracotomy may have a role in selected patients with penetrating injuries to the neck, chest, or extremities and those with signs of life within 5 minutes of arrival to the emergency department.
A resuscitative thoracotomy is seldom of benefit for patients with cardiac arrest secondary to blunt or head injury or for those without vital signs at the scene of the accident. Patients with blunt thoracoabdominal trauma with pulseless electrical activity upon arrival in the emergency department have a survival rate of virtually 0% and are poor candidates for resuscitative thoracotomy. Patients with blunt trauma may be allowed a thoracotomy in the emergency department only if they have signs of life upon arrival to the emergency department.
In a patient with hemoperitoneum from blunt thoracoabdominal trauma, the purpose of a resuscitative thoracotomy in the emergency department is to (1) cross-clamp the aorta, diverting available blood to the coronaries and cerebral vessels during resuscitation; (2) evacuate pericardial tamponade; (3) directly control thoracic hemorrhage; and (4) open the chest for cardiac massage.
Indications for laparotomy in a patient with blunt abdominal injury include signs of peritonitis, uncontrolled shock or hemorrhage, clinical deterioration during observation, and hemoperitoneum findings after FAST or DPL examinations (see Ultrasound in the Imaging Studies section and Diagnostic peritoneal lavage in the Diagnostic Procedures section).
When laparotomy is indicated, broad-spectrum antibiotics are given. A midline incision is usually preferred. When the abdomen is opened, hemorrhage control is accomplished by removing blood and clots, packing all 4 quadrants, and clamping vascular structures. Obvious hollow viscus injuries are sutured. After intra-abdominal injuries have been repaired and hemorrhage has been controlled by packing, a thorough exploration of the abdomen is then performed to evaluate the entire contents of the abdomen.
After intraperitoneal injuries are controlled, the retroperitoneum and pelvis must be inspected. Do not explore pelvic hematomas. Use external fixation of pelvic fractures to reduce or stop blood loss in this region. Explore large or expanding midline retroperitoneal hematomas, with the anticipation of damage to the large vascular structures, pancreas, or duodenum. Do not explore small or stable perinephric hematomas.
After the source of bleeding has been stopped, further stabilizing the patient with fluid resuscitation and appropriate warming is important. After such measures are complete, perform a thorough exploratory laparotomy with the appropriate repair of all injured structures.
Postoperative Details
Patients who had gross enteric contamination of the peritoneal cavity are given appropriate antibiotics for 5-7 days.
If a pelvic hematoma was found and the patient continues to lose blood after external fixation of a pelvic fracture, arteriography with embolization can be used to stop the small percentage of arterial bleeding found in pelvic fractures.
Follow-up
The trend to just observe hemodynamically stable patients with injuries involving the spleen, liver, or kidneys is becoming more popular. In one study of pediatric patients, those with blunt abdominal trauma who were hemodynamically stable after less than 40 mL/kg fluid replacement, had proven evidence of solid organ injuries, and remained stable were admitted to the pediatric intensive care unit under surgical management. No deaths and no immediate or long-term complications were reported in this group.
If the decision has been made to observe the patient, closely monitor vital signs and frequently repeat the physical examination. An increased temperature or respiratory rate can indicate a viscus perforation or an abscess formation. Pulse and blood pressure can also change with sepsis or intra-abdominal bleeding. The development of peritonitis based on physical examination findings is an indication for surgical intervention.
For excellent patient education resources, visit eMedicine's Skin, Hair, and Nails Center. Also, see eMedicine's patient education article Bruises.
Complications
Complications associated with blunt abdominal trauma include but are not limited to the following:
Missed injuries
Delays in diagnosis
Delays in treatment
Iatrogenic injuries
Intra-abdominal sepsis and abscess
Inadequate resuscitation
Delayed splenic rupture
John Udeani, MD, FAAEM, Assistant Professor, Department of Emergency Medicine, Charles Drew University of Medicine and Science, University of California, Los Angeles, David Geffen School of Medicine
Sidney R Steinberg, MD, FACS, Program Director, Department of General Surgery, Spartanburg Regional Healthcare System; Consulting Surgeon, Department of Surgery, WG Hefner Veterans Affairs Medical Center
Updated: Aug 22, 2008
Introduction
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.
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 for several reasons; a few examples are the presence of distracting injuries, an altered mental state, and drug and alcohol intoxication in the patient.
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, 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.
Frequency
United States
By nearly every measure, injury ranks as one of this nation's most pressing health issues. 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. Further review of the data reveals that in those aged 15-25 years, 14,113 persons died from unintentional injuries, 73% of which were related to vehicular trauma. In individuals aged 25-34 years, 57% of the 11,769 deaths reported were from motor vehicle collisions.
In 2001, approximately 30 million people visited emergency departments 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.
International
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. In sub-Saharan Africa, the risk of death from trauma is highest in those aged 15-60 years, and the proportion of such deaths from trauma is higher than in any other region of the world. In South Africa, for instance, the traffic death rate per unit of distance traveled is only surpassed by Korea, Kenya, and Morocco.
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.
Pathophysiology
Vehicular trauma is by far the leading cause of blunt abdominal trauma in the civilian population. Auto-to-auto and auto-to-pedestrian collisions have been cited as causes in 50-75% of cases. Rare causes of blunt abdominal injuries include iatrogenic trauma during cardiopulmonary resuscitation, manual thrusts to clear an airway, and the Heimlich maneuver.
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 is when 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.
The second is when 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 is external compression forces that 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).
Presentation
History
The initial assessment of a trauma patient begins at the scene of the injury, with information provided by the patient, family, bystanders, or paramedics. 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
Whether psychiatric problems were evident
Priorities in resuscitation and diagnosis are established based on hemodynamic stability and the degree of injury. The goal of the primary survey, as directed by the Advanced Trauma Life Support protocol, is to identify and expediently treat life-threatening injuries. The protocol includes the following:
Airway, with cervical spine precautions
Breathing
Circulation
Disability
Exposure
Key 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
Resuscitation is performed concomitantly and continues as the physical examination is completed. The secondary survey is the identification of all injuries via a head-to-toe examination.
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 30-second delay in patient care.
Physical examination
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 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 using diagnostic peritoneal lavage (DPL) or the Focused Assessment with Sonography for Trauma (FAST) examination. The objective is to rapidly identify 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.1 In general, accuracy increases if the patient is examined 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.
The abdominal examination must be systematic. The abdomen is inspected for abrasions or ecchymosis. The seat belt sign, ie, a contusion or abrasion across the lower abdomen, is highly correlated with intraperitoneal pathology. Visual inspection for abdominal distention, which may be due to pneumoperitoneum, gastric dilatation, or ileus produced by peritoneal irritation, is important. 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. Rib fractures involving the lower chest may be associated with splenic or liver injuries. Auscultation of bowel sounds in the thorax may indicate the presence of a diaphragmatic injury. Palpation may reveal local or generalized tenderness, guarding, rigidity, or rebound tenderness, which suggests peritoneal injury.
A rectal examination should be performed 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.
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.
Because of the wide spectrum of injuries, frequent reevaluation is an essential component in the management of patients with blunt abdominal trauma.
Pediatric patients are assessed and treated at least initially as adults with respect to the primary and secondary surveys. However, obvious anatomical and clinical differences exist and these must be kept in mind: the child's physiologic response to injury is different; communication is not always possible; physical examination findings become more important; the pediatric patient's blood volume is less, predisposing them to rapid exsanguination; technical procedures tend to be more time consuming and challenging; and a child's relatively large body surface area contributes to rapid heat loss. Perhaps, the most significant difference between pediatric and adult blunt trauma is that, for the most part, pediatric patients can be resuscitated and treated nonoperatively. Some pediatric surgeons often transfuse up to 40 mL/kg of blood products in an effort to stabilize a pediatric patient. Obviously, if this fails and the child continues to be unstable, laparotomy is indicated.
Tertiary examination
This concept 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.2 The tertiary survey involves a repetition of the primary and secondary surveys and a revision of all laboratory and radiographic studies. In one study, a tertiary trauma survey detected 56% of injuries missed during the initial assessment within 24 hours of admission.
Indications
Aggressive radiographic and surgical investigation is indicated in patients with persistent hyperamylasemia or hyperlipasemia, conditions that suggest significant intra-abdominal injury.
Stable patients with inconclusive physical examination findings should undergo radiographic studies of the abdomen.
DPL is indicated in blunt trauma as follows:
Patients with a spinal cord injury
Those with multiple injuries and unexplained shock
Obtunded patients with a possible abdominal injury
Intoxicated patients in whom abdominal injury is suggested
Patients with potential intra-abdominal injury who will undergo prolonged anesthesia for another procedure
An indication for immediate blood transfusion is hemodynamic instability despite the administration of 2 L of fluid to adult patients; this instability indicates ongoing blood loss.
Indications for laparotomy in a patient with blunt abdominal injury include the following:
Signs of peritonitis
Uncontrolled shock or hemorrhage
Clinical deterioration during observation
Hemoperitoneum findings after FAST or DPL examinations
Finally, surgical intervention is indicated in patients with evidence of peritonitis based on physical examination findings.
Relevant 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 for 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, the 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 based on physical examination findings. Evaluation of the structures in this region may require a CT scan, angiography, and an intravenous pyelogram.
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, DPL is a useful adjunct.
Contraindications
While not a contraindication to surgical repair, the evaluation of a patient with blunt abdominal trauma must be prioritized based on the most urgent problems. This implies that injuries involving the head, the respiratory system, or the cardiovascular system may take precedence over an abdominal injury.
Although a nasogastric tube is routine in order to decompress the stomach and assess for the presence of blood, it is contraindicated in patients with basilar skull fracture. An orogastric tube is preferred if the patient has evidence of a maxillofacial injury.
Operative treatment is not indicated in every patient with positive FAST scan results. Hemodynamically stable patients with positive FAST findings may require a CT scan to better define the nature and extent of their injuries. Operating on every patient with positive FAST scan findings may result in an unacceptably high laparotomy rate.
The only absolute contraindication to DPL is the obvious need for laparotomy. Relative contraindications include morbid obesity, a history of multiple abdominal surgeries, and pregnancy.
Resuscitative thoracotomy is not recommended in patients with blunt thoracoabdominal trauma who have pulseless electrical activity upon arrival in the emergency department. The survival rate in this situation is virtually 0%. These patients may be allowed a thoracotomy in the emergency department only if they have signs of life upon arrival to the emergency department.
Workup
Laboratory Studies
Valuable blood studies in the initial evaluation of a patient with blunt abdominal trauma vary by institution but should include a CBC count, coagulation studies, blood type, and blood cross-match (if indicated). The presence of massive hemorrhage is usually obvious from hemodynamic parameters, and the hematocrit value merely confirms the diagnosis.
Urine studies include urinalysis, urine toxicologic screen, and serum or urine pregnancy tests in females of appropriate 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.
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 should raise the suggestion of significant intra-abdominal injury and is an indication for aggressive radiographic and surgical investigation.
All patients should have their tetanus immunization history reviewed. If it is not current, prophylaxis should be given.
Imaging Studies
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 using DPL or the FAST scan. Radiographic studies of the abdomen are indicated in stable patients when the physical examination findings are inconclusive.
Plain radiograph
Although the overall value of plain films in the evaluation of patients with blunt abdominal trauma is limited, they 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.
Ultrasound
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 ultrasound in the evaluation of blunt abdominal trauma was published in 1992 by Tso and colleagues.3 Since then, numerous articles have been published in the United States advocating the use of ultrasound in the evaluation of the patient with blunt abdominal trauma.
Bedside ultrasonography is a rapid, portable, noninvasive, and accurate examination that can be performed by emergency clinicians and trauma surgeons to detect hemoperitoneum. In fact, in many medical centers, the FAST examination has virtually replaced DPL as the procedure of choice in the evaluation of hemodynamically unstable trauma patients.
An examination is interpreted as positive if fluid is found in any of the 4 acoustic windows and is interpreted as negative if no fluid is seen. An examination is deemed indeterminate if any of the windows cannot be adequately assessed.
In 1996, the examination was first termed Focused Abdominal Sonography for Trauma. However, in 1997, the FAST Consensus Conference Committee concluded that the acronym should stand for Focused Assessment with Sonography for Trauma. That same year, the American College of Surgeons included the use of ultrasound in the Advanced Trauma Life Support secondary survey.
The FAST examination is based on the assumption that all clinically significant abdominal injuries are associated with hemoperitoneum. However, the detection of free intraperitoneal fluid is based on factors such as the body habitus, injury location, presence of clotted blood, position of the patient, and amount of free fluid present.
The minimum threshold for detecting hemoperitoneum is unknown and remains a subject of interest. Kawaguchi and colleagues found that 70 mL of blood could be detected,4 while Tiling et al found that 30 mL is the minimum requirement for detection with ultrasound.5 They also concluded that a small anechoic stripe in the Morison pouch represents approximately 250 mL of fluid, while 0.5-cm and 1-cm stripes represent approximately 500 mL and 1 L of free fluid, respectively.
The current examination protocol consists of 4 acoustic windows with the patient supine. These windows are pericardiac, perihepatic, perisplenic, and pelvic (known as the 4 Ps).
The pericardial view is obtained using a subcostal or transthoracic window. It provides a 4-chamber view of the heart and can detect the presence of hemopericardium, which is demonstrated by the separation of the visceral and parietal pericardial layers. The perihepatic view images portions of the liver, diaphragm, and right kidney. It reveals fluid in the Morison pouch, the subphrenic space, and the right pleural space. The perisplenic view provides views of the spleen and the left kidney and reveals fluid in the splenorenal recess, the left pleural space, and the subphrenic space. The pelvic view uses the bladder as a sonographic window. This view is best accomplished while the patient has a full bladder. In males, free fluid is seen as an anechoic area (sonographically black) in the rectovesicular pouch or cephalad to the bladder. In females, fluid accumulates in the Douglas pouch, posterior to the uterus.
Reported sensitivities and negative predictive values for ultrasound in the detection of hemoperitoneum are 78-99% and 93-99%, respectively.
FAST examination relies on hemoperitoneum to identify patients with injury. Chiu and colleagues, in their study of 772 patients with blunt trauma undergoing FAST scans, reported 52 patients had an abdominal injury.6 Of the 52 patients, 15 (29%) had no hemoperitoneum on FAST or CT scan results. Hence, the reliance of hemoperitoneum as the sole indicator of abdominal visceral injury limits the utility of FAST as a diagnostic screening tool in stable patients with blunt abdominal trauma.
Rozycki et al studied 1540 patients and reported that ultrasound was the most sensitive and specific modality for the evaluation of hypotensive patients with blunt abdominal trauma (sensitivity and specificity, 100%).7
Hemodynamically stable patients with positive FAST results may require a CT scan to better define the nature and extent of their injuries. Taking every patient with a positive FAST result to the operating room may result in an unacceptably high laparotomy rate.
Hemodynamically stable patients with negative FAST results require close observation, serial abdominal examinations, and a follow-up FAST examination. However, strongly consider performing a CT scan, especially if the patient is intoxicated or has other associated injuries.
Hemodynamically unstable patients with negative FAST results are a diagnostic challenge. Options include DPL, exploratory laparotomy, and, possibly, a CT scan after aggressive resuscitation.
Computed tomography
The CT scan remains the criterion standard for the detection of solid organ injuries. In addition, a CT scan of the abdomen can reveal other associated injuries, notably vertebral and pelvic fractures and injuries in the thoracic cavity.
CT scans, unlike DPL or FAST examinations, have the capability to determine the source of hemorrhage. In addition, many retroperitoneal injuries go unnoticed with DPL and FAST examinations.
CT scans provide excellent imaging of the pancreas, duodenum, and genitourinary system. The images can help quantitate the amount of blood in the abdomen and can reveal individual organs with precision.
Limitations of CT scans include marginal sensitivity for diagnosing diaphragmatic, pancreatic, and hollow viscus injuries. Also, they are relatively expensive and time consuming and require oral or intravenous contrast, which may cause adverse reactions.
Other Tests
Laparoscopy
The introduction of minimally invasive surgery has revolutionized many surgical diagnostic protocols. In the late 1980s and early 1990s, considerable interest was garnered for the use of laparoscopy in the evaluation and management of blunt and penetrating abdominal trauma. However, subsequent studies revealed major limitations and cautioned against its widespread use. The most important limitation is its inability to reliably identify hollow viscus and retroperitoneal injuries, even in the hands of experienced laparoscopists
The procedure involves placing a subumbilical or subcostal trocar for the introduction of the laparoscope and creating other ports for retractors, clamps, and other tools necessary for visualization of the repair.
Diagnostic laparoscopy has been most useful in the evaluation of possible diaphragmatic injuries, especially in penetrating thoracoabdominal injuries on the left side.
In blunt trauma, diagnostic laparoscopy offers no clear advantage over less invasive modalities such as DPL or CT scan and complications can occur from trocar misplacement.
Diagnostic Procedures
Diagnostic peritoneal lavage
The idea of evaluating the abdomen by analyzing its contents was first used in the diagnosis of acute abdominal conditions. The principle was described by Salomon in 1906. He described the passage of a urethral catheter by means of a trocar inserted through the abdominal wall to obtain samples of peritoneal fluid to establish the diagnosis of peritonitis from infectious agents (eg, pneumococcal or tuberculous organisms). This technique has since been refined and is now known as abdominal paracentesis. In 1926, Neuhof and Cohen described the sampling of peritoneal fluid in cases of acute pancreatitis and blunt abdominal trauma by passing a spinal needle through the abdominal wall.8 In 1965, Root et al reported the use of diagnostic percutaneous peritoneal lavage in patients after blunt abdominal trauma.9
DPL is indicated in blunt trauma in (1) patients with a spinal cord injury, (2) those with multiple injuries and unexplained shock, (3) obtunded patients with a possible abdominal injury, (4) intoxicated patients in whom abdominal injury is suggested, and (5) patients with potential intra-abdominal injury who will undergo prolonged anesthesia for another procedure.
The only absolute contraindication to DPL is the obvious need for laparotomy. Relative contraindications include morbid obesity, a history of multiple abdominal surgeries, and pregnancy.
Various methods of introducing the catheter into the peritoneal space have been described. These include the open, semiopen, and closed methods. The open method requires an infraumbilical skin incision that is extended to and through the linea alba. The peritoneum is opened, and the catheter is inserted under direct visualization. The semiopen method is identical except the peritoneum is not opened and the catheter is delivered percutaneously through the peritoneum into the peritoneal cavity. The closed technique requires the catheter to be inserted blindly through the skin, subcutaneous tissue, linea alba, and peritoneum. The closed and semiopen techniques at the infraumbilical site are preferred at most centers. The fully open method is the most technically demanding and is restricted to those situations in which the closed or semiopen technique is unsuccessful or is deemed unsafe (eg, patients with pelvic fractures, pregnancy, obesity, or prior abdominal operations).
DPL results are considered positive in a blunt trauma patient if 10 mL of grossly bloody aspirate is obtained before infusion of the lavage fluid or if the siphoned lavage fluid (ie, 1 L normal saline infused into the peritoneal cavity via a catheter and allowed to mix, which is then drained by gravity) has more than 100,000 RBC/mL, more than 500 WBC/mL, elevated amylase content, bile, bacteria, vegetable matter, or urine. Only approximately 30 mL of blood is needed in the peritoneum to produce a microscopically positive DPL result.
DPL has been shown in some studies to have diagnostic accuracy of 98-100%, sensitivity of 98-100%, and specificity of 90-96%. It has some advantages, including high sensitivity, rapidity, and immediate interpretation. Its limitations include iatrogenic abdominal injury and its high sensitivity, which can lead to nontherapeutic laparotomies. False-positive DPL results can occur if an infraumbilical approach is used in a patient with a pelvic fracture. A pelvic x-ray film should be obtained prior to performing DPL if a pelvic fracture is suggested. Before DPL is attempted, the urinary bladder and stomach should be decompressed.
With the availability of fast, noninvasive, and better imaging modalities (eg, FAST examination, CT scan), the role of DPL is now limited to the evaluation of unstable trauma patients in whom FAST results are negative or inconclusive.
Treatment
Medical Therapy
The initial goal of paramedics with Advanced Trauma Life Support training is to rapidly assess the patient's airway with cervical spine precautions, breathing, and circulation. This is then followed by splinting of fractures and control of external hemorrhage. The injured patient is at risk for progressive deterioration from continued bleeding and requires rapid transport to a trauma center or the closest and most appropriate facility, with appropriate stabilization procedures performed en route. Hence, securing the airway, placing large-bore intravenous lines, and administering intravenous fluid must take place en route, unless delays in transport occur, for instance, if prolonged extrication is required.
Upon arrival at the emergency department or trauma center, the first priority is reassessment of the airway. Protection of the cervical spine with in-line immobilization is absolutely mandatory. If intubation is indicated, attempt nasotracheal (ie, if no contraindications) or endotracheal intubation. If unsuccessful, perform cricothyroidotomy. After an airway has been established, adequate ventilatory exchange is assessed by auscultation of both lung fields. Clinical diagnosis of a tension pneumothorax is treated with needle decompression followed by chest thoracostomy tube placement. Other mechanical factors that can interfere with ventilation include sucking chest wounds, a hemothorax, and pulmonary contusion. Treat these aggressively and expediently.
The next priority in the primary survey is an assessment of the circulatory status of the patient. Circulatory collapse in a patient with blunt abdominal trauma is usually caused by hypovolemia from hemorrhage. Effective volume resuscitation is accomplished by controlling external hemorrhage and infusing warmed crystalloid solution via 2 large-bore peripheral intravenous lines. Hemodynamic instability despite the administration of 2 L of fluid to adult patients indicates ongoing blood loss and is an indication for immediate blood transfusion. Administer type O, Rh-negative blood if cross-matched or type-specific blood is not available.
The primary survey is completed with a brief neurologic assessment of the patient using elements of the Glasgow Coma Scale. The patient is undressed and draped in clean, dry, warm sheets.
The secondary survey consists of a complete and thorough physical examination as indicated under Physical examination in the Clinical section.
Nonoperative management of blunt abdominal trauma
Nonoperative management strategies based on CT scan diagnosis and the hemodynamic stability of the patient are now being used in the treatment of adult solid organ injury, primarily the liver and spleen. In blunt abdominal trauma, including severe solid organ injuries, selective nonoperative management has become the standard of care.
Angiography is a valuable modality in the nonoperative management of adult abdominal solid organ injuries from blunt trauma. It is used aggressively for nonoperative control of hemorrhage, thus avoiding nontherapeutic cost-inefficient laparotomies.
Surgical Therapy
Resuscitative thoracotomy in the emergency department is only occasionally life-saving. It is an aggressive, desperate measure to save a patient in whom death is thought to be imminent or otherwise inevitable. Survival with good neurologic recovery is more likely for patients with penetrating trauma than for patients with blunt trauma. Thoracotomy may have a role in selected patients with penetrating injuries to the neck, chest, or extremities and those with signs of life within 5 minutes of arrival to the emergency department.
A resuscitative thoracotomy is seldom of benefit for patients with cardiac arrest secondary to blunt or head injury or for those without vital signs at the scene of the accident. Patients with blunt thoracoabdominal trauma with pulseless electrical activity upon arrival in the emergency department have a survival rate of virtually 0% and are poor candidates for resuscitative thoracotomy. Patients with blunt trauma may be allowed a thoracotomy in the emergency department only if they have signs of life upon arrival to the emergency department.
In a patient with hemoperitoneum from blunt thoracoabdominal trauma, the purpose of a resuscitative thoracotomy in the emergency department is to (1) cross-clamp the aorta, diverting available blood to the coronaries and cerebral vessels during resuscitation; (2) evacuate pericardial tamponade; (3) directly control thoracic hemorrhage; and (4) open the chest for cardiac massage.
Indications for laparotomy in a patient with blunt abdominal injury include signs of peritonitis, uncontrolled shock or hemorrhage, clinical deterioration during observation, and hemoperitoneum findings after FAST or DPL examinations (see Ultrasound in the Imaging Studies section and Diagnostic peritoneal lavage in the Diagnostic Procedures section).
When laparotomy is indicated, broad-spectrum antibiotics are given. A midline incision is usually preferred. When the abdomen is opened, hemorrhage control is accomplished by removing blood and clots, packing all 4 quadrants, and clamping vascular structures. Obvious hollow viscus injuries are sutured. After intra-abdominal injuries have been repaired and hemorrhage has been controlled by packing, a thorough exploration of the abdomen is then performed to evaluate the entire contents of the abdomen.
After intraperitoneal injuries are controlled, the retroperitoneum and pelvis must be inspected. Do not explore pelvic hematomas. Use external fixation of pelvic fractures to reduce or stop blood loss in this region. Explore large or expanding midline retroperitoneal hematomas, with the anticipation of damage to the large vascular structures, pancreas, or duodenum. Do not explore small or stable perinephric hematomas.
After the source of bleeding has been stopped, further stabilizing the patient with fluid resuscitation and appropriate warming is important. After such measures are complete, perform a thorough exploratory laparotomy with the appropriate repair of all injured structures.
Postoperative Details
Patients who had gross enteric contamination of the peritoneal cavity are given appropriate antibiotics for 5-7 days.
If a pelvic hematoma was found and the patient continues to lose blood after external fixation of a pelvic fracture, arteriography with embolization can be used to stop the small percentage of arterial bleeding found in pelvic fractures.
Follow-up
The trend to just observe hemodynamically stable patients with injuries involving the spleen, liver, or kidneys is becoming more popular. In one study of pediatric patients, those with blunt abdominal trauma who were hemodynamically stable after less than 40 mL/kg fluid replacement, had proven evidence of solid organ injuries, and remained stable were admitted to the pediatric intensive care unit under surgical management. No deaths and no immediate or long-term complications were reported in this group.
If the decision has been made to observe the patient, closely monitor vital signs and frequently repeat the physical examination. An increased temperature or respiratory rate can indicate a viscus perforation or an abscess formation. Pulse and blood pressure can also change with sepsis or intra-abdominal bleeding. The development of peritonitis based on physical examination findings is an indication for surgical intervention.
For excellent patient education resources, visit eMedicine's Skin, Hair, and Nails Center. Also, see eMedicine's patient education article Bruises.
Complications
Complications associated with blunt abdominal trauma include but are not limited to the following:
Missed injuries
Delays in diagnosis
Delays in treatment
Iatrogenic injuries
Intra-abdominal sepsis and abscess
Inadequate resuscitation
Delayed splenic rupture
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