Initial evaluation and management of blunt abdominal trauma in adults

INTRODUCTION — Blunt abdominal trauma (BAT) is regularly encountered in the emergency department (ED). The lack of historical data and the presence of distracting injuries or altered mental status, from head injury or intoxication, can make these injuries difficult to diagnose and manage. Victims of blunt trauma often have both abdominal and extra-abdominal injuries, further complicating care.

The initial evaluation and management of patients with BAT are reviewed here. Discussions of penetrating abdominal trauma, general management of the acutely injured adult, and other aspects of the initial evaluation and management of adult trauma are found separately:

●General trauma evaluation and management (see "Initial management of trauma in adults" and "Emergency ultrasound in adults with abdominal and thoracic trauma")

●Penetrating abdominal trauma (see "Initial evaluation and management of abdominal stab wounds in adults" and "Initial evaluation and management of abdominal gunshot wounds in adults")

●Genitourinary and pelvic trauma (see "Blunt genitourinary trauma: Initial evaluation and management" and "Penetrating trauma of the upper and lower genitourinary tract: Initial evaluation and management" and "Pelvic trauma: Initial evaluation and management")

●Thoracic trauma (see "Initial evaluation and management of blunt thoracic trauma in adults" and "Initial evaluation and management of chest wall trauma in adults" and "Initial evaluation and management of penetrating thoracic trauma in adults")

EPIDEMIOLOGY — Blunt abdominal trauma (BAT) accounts for the majority (80 percent) of abdominal injuries seen in the emergency department (ED) [1] and is responsible for substantial morbidity and mortality. The majority of BAT cases (75 percent) are related to motor vehicle collision or auto versus pedestrian accidents [2]. Blows to the abdomen and falls are responsible for 15 and 6 to 9 percent, respectively [3]. Occult BAT may occur with child abuse and domestic violence. (See "Physical child abuse: Diagnostic evaluation and management".)

The prevalence of intra-abdominal injury among patients presenting to the ED with BAT is approximately 13 percent [1]. The spleen and liver are the most commonly injured solid organs [2,3]. Injuries to the pancreas, bowel and mesentery, bladder, and diaphragm, as well as retroperitoneal structures (kidneys, abdominal aorta), are less common but must be considered. Patients presenting with signs of BAT from seatbelts are at relatively higher risk for hollow viscus injury, although the overall risk of injury is low [4].

MECHANISM OF INJURY — Several pathophysiologic mechanisms can occur in patients with blunt abdominal trauma (BAT) [3,5]. A sudden and pronounced rise in intra-abdominal pressure created by outward forces can rupture a hollow viscus. Passengers wearing a lap belt without a shoulder attachment can sustain injury from such a mechanism when the belt forcefully compresses the abdomen.

Blunt forces exerted against the anterior abdominal wall can compress abdominal viscera against the posterior thoracic cage or vertebral column, crushing tissue. Solid organs (eg, spleen and liver) are particularly susceptible to laceration or fracture by this mechanism. Older adults and alcoholic patients generally have lax abdominal walls and are more likely to sustain such injuries. Delayed splenic rupture can occur. Retroperitoneal structures, such as the duodenum or pancreas, may be injured.

Shearing forces created by sudden deceleration can cause lacerations of both solid and hollow organs at their points of attachment to the peritoneum. They may also create tears at vascular pedicles or cause stretch injuries to the intima and media of arteries, resulting in infarction of the susceptible organ. The kidney is most susceptible to such stretch injury.

Fractured ribs or pelvic bones can lacerate intra-abdominal tissue.

HISTORY — Historical features related to motor vehicle collisions (the cause of most blunt abdominal trauma [BAT]) to consider include the following:

●Fatality at the scene

●Vehicle type and velocity

●Whether the vehicle rolled over (rollover mechanism is associated with increased risk of serious injury)

●Patient's location within the vehicle (seat position on the side of impact is associated with serious thoracoabdominal injury in side-impact crashes) [6]

●Extent of intrusion into the passenger compartment (intrusion into passenger space >6 inches [15 cm] is associated with increased risk of injury) [7]

●Extent of damage to the vehicle

●Steering wheel deformity (associated with increased risk of thoracoabdominal injury for front seat passengers) [8]

●Whether seatbelts were used and, if so, what type (eg, use of lap belt alone increases risk for Chance fracture (image 1))

●Whether front or side air bags deployed

These features include several traditionally associated with significant injury, although the diagnostic utility of historical features in BAT remains unclear. Physiologic and examination findings are more accurate predictors of clinically significant injury. (See 'Evaluation and management' below.)

The history as part of the general trauma assessment is discussed separately [9]. (See "Initial management of trauma in adults".)

Unrestrained victims are at higher risk of injury than those who are restrained [10]. Paradoxically, steering wheel deformity may be an independent predictor of abdominal injury in front seat passengers but not drivers [8,11].

The magnitude of injury to pedestrians varies with the speed and size of the striking vehicle. Pedestrians often sustain a triad of injuries to the leg, torso, and cranium; injury to any of these sites should prompt careful evaluation of the other two [12,13].

Historical data may be helpful, but mechanism alone cannot reliably predict the need for emergency laparotomy. Information gained from prehospital personnel including vital signs, physiologic abnormalities such as fluctuations in vital signs, examination findings, diagnostic test results (eg, ultrasound), and knowledge of underlying medical conditions is more useful for identifying injuries and determining clinical risk [11]. Older adults are at particularly high risk. (See 'Evaluation and management' below and "Geriatric trauma: Initial evaluation and management".)

EVALUATION AND MANAGEMENT — Initial management of the trauma patient is directed at rapid stabilization and identification of life-threatening injuries as described in advanced trauma life support (ATLS) protocols. Primary assessment (ie, the primary survey) follows the ABCDE pattern: airway, breathing, circulation, disability (neurologic status), and exposure. Details related to the initial management of blunt abdominal trauma (BAT) are discussed below; a basic algorithm for management of BAT is provided (algorithm 1). The initial evaluation of the trauma patient is reviewed in detail separately. (See "Initial management of trauma in adults" and "Trauma management: Approach to the unstable child".)

Initial assessment and physical examination — BAT can manifest a wide range of presentations, from a patient with normal vital signs and minor complaints to an obtunded patient in severe shock. The initial presentation may be benign despite the presence of significant intra-abdominal injury. If evidence of extra-abdominal injury exists, the emergency clinician must assess for intra-abdominal injury, even in hemodynamically stable patients without abdominal complaints. In the hemodynamically unstable patient, concurrent resuscitation and assessment are paramount. The absence of abdominal pain or tenderness does not rule out the presence of significant intra-abdominal injury.

According to a systematic review of 12 studies involving 10,757 patients, the physical examination findings most strongly associated with intra-abdominal injury following BAT are the following [1]:

●Seatbelt sign (likelihood ratio [LR] range 5.6 to 9.9 (picture 1); subsequent observational evidence supports the association of the seatbelt sign with intra-abdominal injury [14])

●Rebound tenderness (uncommon but substantially increases risk when present; LR 6.5, 95% CI 1.8-24)

●Hypotension (defined as systolic blood pressure <90 mmHg; LR 5.2, 95% CI 3.5-7.5)

●Abdominal distension (LR 3.8, 95% CI 1.9-7.6)

●Abdominal guarding (LR 3.7, 95% CI 2.3-5.9)

●Concomitant femur fracture (LR 2.9, 95% CI 2.1-4.1; femur fractures are significant distracting injuries and may indicate BAT among pedestrians stuck by automobiles)

Of note, although abdominal pain and abdominal tenderness did increase the likelihood of intra-abdominal injury among patients with BAT, the negative likelihood ratio for each is low; thus, as noted above, the absence of either finding cannot be used to exclude injury. In addition, while the absence of the above signs and symptoms decreases the likelihood of intra-abdominal injury (LR 0.52-0.96), their absence, alone or in combination, is not sufficient to rule out intra-abdominal injury. This systematic review included only studies that have a clear reference standard (eg, computed tomography [CT], diagnostic peritoneal lavage [DPL], laparotomy) and were performed at major academic trauma centers.

●Hypotension – Hypotension following BAT most often results from hemorrhage from a solid abdominal organ or intra-abdominal vascular injury. Although clinicians must look for extra-abdominal sources of bleeding (eg, scalp laceration, thoracic injury, or long bone fracture), an extra-abdominal source of hemorrhage never obviates the need to evaluate the peritoneal cavity. Head injury alone cannot explain shock except in rare cases of profound intracranial trauma or in infants who may have significant intracranial bleeding or cephalohematoma [15].

●Abdominal findings including seatbelt sign – The location of an abdominal seatbelt sign (picture 1) is worth noting. An observational study of emergency department (ED) patients with BAT after motor vehicle collisions found that an abdominal seatbelt sign above the anterior-superior iliac spine (ASIS) was associated with a fourfold increase in the risk of intra-abdominal or lumbar injury [16,17]. Patients with seatbelt signs at or below the level of the ASIS had a rate of injury similar to those without a seatbelt sign.

Abdominal wall ecchymosis, abdominal distention, and decreased bowel sounds may herald intra-abdominal injury. The seatbelt sign (ecchymosis over the abdominal wall in the distribution of the seatbelt) indicates intra-abdominal injury in up to one-third of patients [1,18,19]. Abdominal distention, resulting from peritoneal irritation producing an ileus, pneumoperitoneum, or gastric dilation, can indicate significant injury. Clinicians should never wait for such signs of hemoperitoneum, as the blood volume required to create distention exceeds that of the entire vasculature. Decreased bowel sounds can result from chemical peritonitis caused by hemorrhage or from a ruptured hollow viscus. Bowel sounds heard in the chest suggest the presence of diaphragmatic rupture.

In alert patients free of distracting injuries, the most reliable symptoms and signs of BAT are abdominal pain, abdominal tenderness, and peritoneal findings, particularly when risk factors for abdominal injury are present. Patients with visceral injury present with local or general abdominal tenderness in up to 90 percent of cases. The presence of pain at the left costal margin has been associated with splenic injury in up to 5.6 percent of patients [20]. However, such signs are not specific and may also be found with isolated thoracoabdominal wall contusions or lower rib fractures. More importantly, the absence of abdominal tenderness in an awake, hemodynamically stable patient without a distracting extra-abdominal injury indicates that intra-abdominal injury is highly unlikely.

While intra-abdominal injury may occur in conscious patients without abdominal tenderness, it is uncommon; evidence suggests that the absence of abdominal pain or tenderness is sensitive for ruling out injury in the alert, nonintoxicated patient [1,21-25]. It is not reliable in patients who are intoxicated or have sustained a head injury or multiple other injuries.

●Altered sensorium and extra-abdominal injury – The presence of an altered sensorium or painful extra-abdominal injuries in victims of blunt trauma should raise suspicion for abdominal injury, even in the absence of suggestive symptoms or signs [1]. Up to 10 percent of patients with an apparently isolated head injury may have concomitant intra-abdominal injuries [26], and, according to one prospective observational study, 7 percent of blunt trauma patients with distracting extra-abdominal injuries have an abdominal injury despite the absence of abdominal pain or tenderness [27].

●Referred pain – Intra-abdominal injury may cause referred pain. As examples, splenic injury associated with blood adjacent to the left hemidiaphragm may cause referred pain at the left shoulder (Kehr sign) while a similar phenomenon associated with liver injury may cause referred pain at the right shoulder.

●Rectal examination – The digital rectal examination (DRE) has poor sensitivity for bowel injuries and should not be performed routinely. The examination is warranted in some cases, including when urethral or penetrating rectal injury is suspected. The DRE is discussed in greater detail separately. (See "Initial management of trauma in adults", section on 'Rectum and genitourinary'.)

●Structured examination – The results of a large prospective observational study suggest that use of a careful, structured physical examination in alert patients following blunt trauma reduces the risk of missing a clinically significant intra-abdominal injury due to an extra-abdominal distracting injury [28]. However, we believe it is important to remain cautious in such circumstances and to maintain a low threshold for obtaining diagnostic imaging.

Laboratory tests — Routine laboratory tests are generally of limited value in the management of the acutely traumatized patient but may be helpful in identifying patients at low risk for significant injury, for whom CT may safely be omitted. Clinicians should consider laboratory tests adjuncts to diagnosis and not substitutes for clinical or radiologic assessment in BAT. We do suggest obtaining a microscopic urinalysis in victims of BAT when the presence of intra-abdominal injury is unclear, as microscopic hematuria (>25 red blood cells per high-power field) increases the likelihood of significant intra-abdominal injury (see the discussion of urinalysis immediately below). The appropriate use of laboratory tests in the initial evaluation of trauma is reviewed separately; the use of tests of particular relevance to blunt abdominal trauma is discussed here. (See "Initial management of trauma in adults", section on 'Laboratory tests'.)

●Hematocrit – A hematocrit below 30 percent increases the likelihood of intra-abdominal injury in the setting of BAT (LR 3.3, 95% CI 2.4-4.5) [1,29]. Anemia must be interpreted considering the clinical context, including the extent of hemorrhage, time since the injury, and the volume of exogenous fluid administration. The clinician should not be reassured by a normal hematocrit in the acute trauma patient with hypotension; internal hemorrhage should be assumed in such cases.

●Leukocyte count – In BAT, the white blood cell count is nonspecific and of little value [21,30,31]. The positive and negative predictive value of, respectively, an elevated or normal white blood cell count is poor. Catecholamine release due to trauma can cause demargination and may elevate the white blood cell count to 12,000 to 20,000/mm³ with a moderate left shift. Solid or hollow viscus injury can cause comparable elevations [32].

●Pancreatic enzymes – Normal serum amylase and lipase concentrations cannot exclude significant pancreatic injury [33]. While elevated concentrations raise the possibility of pancreatic injury, they may be caused by nonpancreatic abdominal injury as well and alone are nondiagnostic. If pancreatic injury is suspected, confirmatory studies (eg, CT scan) are needed.

●Liver function tests – Hepatic injury is associated with elevations in liver transaminase concentrations (LR 2.5-5.2), and there is some evidence that higher elevations increase the odds for injury and the likelihood of severe injury [1,31,34,35]. In a retrospective study of 676 adult patients who underwent CT imaging within three hours of BAT, of whom 64 were diagnosed with hepatic injury, a threshold of 109 units per liter for aspartate aminotransferase (AST) and 97 units per liter for alanine aminotransferase (ALT) showed 84 percent sensitivity and 98 percent negative predictive value for the detection of hepatic injury [35]. However, patients with comorbidities such as alcohol-induced liver disease or hepatitis may have elevated transaminase concentrations at baseline.

●Urinalysis – Gross hematuria suggests serious renal injury and mandates further investigation. (See "Blunt genitourinary trauma: Initial evaluation and management".)

According to a meta-analysis of 12 studies, microscopic hematuria (>25 red blood cells per high-power field) increases the likelihood of significant intra-abdominal injury (LR 3.7-4.1) [1]. Therefore, when the presence of intra-abdominal injury is unclear, it is prudent to perform microscopic urinalysis in victims of BAT [36]. In a prospective observational study of 196 patients with BAT, the combination of abdominal tenderness and microscopic hematuria was 64 percent sensitive and 94 percent specific in predicting intra-abdominal injury, as determined by abdominal CT [37].

Point-of-care urinalysis (ie, urine dipstick) is a reasonable screening examination in patients felt to be at low risk of BAT based on their clinical presentation. If the test is positive, it can be followed up with microscopic urinalysis or CT imaging. Patients with a negative formal urinalysis are at low risk of intra-abdominal injury [38]. However, point-of-care urinalysis should be interpreted cautiously. In one retrospective study, the sensitivity of point-of-care urinalysis for intra-abdominal injury (identified by CT) was 72 percent in patients with demonstrated BAT [39]. Clinicians should not allow a negative test to dissuade them from further investigation in the presence of concerning clinical signs (eg, abdominal tenderness).

●Base deficit and lactate – A prospective, nonrandomized study of BAT patients in two trauma centers found that a base deficit less than -6 was associated with intra-abdominal hemorrhage and the need for laparotomy and blood transfusion [40]. Clinicians should be aware of these results if such laboratory studies are performed, while recognizing that base deficit and lactate elevation are nonspecific findings that may not be directly related to traumatic injury.

●Pregnancy test – Obtain a pregnancy test in female patients of childbearing age with BAT when pregnancy status is unknown. Hemodynamic and laboratory parameters change during later pregnancy. Early or mid-stage pregnancy may not be obvious, and the patient may need treatment with anti-D immune globulin (Rho(D) immune globulin). (See "Initial evaluation and management of major trauma in pregnancy".)

●Additional tests – Clinical circumstance should determine the need for further testing (eg, patient taking anticoagulant or antiplatelet medications would likely prompt coagulation studies).

Imaging studies

Warnings — Imaging studies can provide important information to guide the care of patients with BAT but are not without risk. The traumatized patient must be stabilized before most radiographic studies can be performed, and clinicians must pay careful attention to potential spinal cord injuries and guard against further injury during positioning and transfer for radiographic studies.

The uncooperative patient may interfere with the performance of radiologic studies, limiting study quality, while putting themselves at risk for cervical spine injury. Clinicians must evaluate the patient to determine the likely cause for their uncooperativeness (eg, hypoxia, traumatic brain injury). Combative patients may require sedation to obtain needed studies.

A clinician familiar with trauma care must accompany any patient who has the potential to deteriorate precipitously. Although many trauma centers have CT scanners adjacent to the ED, this is not always the case. Leaving a patient unattended in the radiology department for even a brief period can have disastrous consequences. In addition to patients with likely intra-abdominal injury, radiologic studies of the abdomen are indicated in stable patients when the physical examination and laboratory tests are inconclusive, and the information will guide therapy.

Plain radiographs — Trauma series radiographs, typically including portable radiographs of the chest and pelvis, are often obtained in an unstable patient with BAT [41]. Patients who have sustained blunt trauma to the torso are at risk for intrathoracic as well as intra-abdominal injury, and plain radiographs of the chest may be helpful depending upon the clinical circumstances. The indications and use of chest imaging in patients with blunt thoracic trauma are reviewed separately. (See "Initial evaluation and management of blunt thoracic trauma in adults", section on 'Chest computed tomography for most patients' and "Initial evaluation and management of blunt thoracic trauma in adults", section on 'Diagnostic testing in Stable/Stabilized Patient'.)

Findings on chest radiograph that suggest intra-abdominal injury include:

●Lower rib fractures (image 2)

●Diaphragmatic hernia (image 3)

●Free air under the diaphragm (image 4)

A portable radiograph of the pelvis can demonstrate unstable pelvic fractures (image 5) and hip dislocation. Intra-abdominal injury should be suspected in any patient with a fracture involving the pelvic ring. In these patients, plain films should be followed with CT imaging of the abdomen and pelvis. (See "Pelvic trauma: Initial evaluation and management".)

In patients who are hemodynamically stable and for whom CT imaging is planned, it is reasonable to defer plain films as CT provides far greater diagnostic accuracy. If there is a high likelihood of thoracic or pelvic injury, or a delay in performing CT is anticipated, plain radiographs should be performed at the bedside [42].

Computed tomography

Indications — Our use of CT in the assessment of patients with BAT depends upon the clinical circumstances and is described below (see 'Management by clinical scenario' below). The issue of comprehensive whole-body CT imaging following trauma ("pan scan") is discussed separately. (See "Initial management of trauma in adults", section on 'Computed tomography, including total body CT'.)

We perform abdominal and pelvic CT with intravenous (IV) contrast in any patient with one or more high-risk clinical findings and in any patient with persistent abdominal pain or tenderness on serial examinations (eg, persistent tenderness on exams performed 30 minutes apart). CT may also be needed for patients who are hemodynamically stable but whose sensorium or reliability is altered by closed head injury, drug or alcohol intoxication, or significant distracting injury.

In general, we concur with the approach outlined in the clinical policy of the American College of Emergency Physicians (ACEP), which states that patients with none of the following are at low risk of intra-abdominal injury, and CT may be omitted [43]:

•Hypotension

•Abdominal or costal margin tenderness

•Altered mental status (Glasgow Coma Scale score ≤14)

•Abnormal chest radiograph

•Hematocrit ≤30 percent

•Hematuria

Accuracy, advantages, disadvantages — Owing to its speed and accuracy, multidetector CT has become the primary method for identifying intra-abdominal injury [1,44]. The sensitivity and specificity of CT for identifying significant intra-abdominal pathology are high (97 to 98 percent and 97 to 99 percent, respectively) [1,45,46]. In patients with suspected BAT who have a negative abdominal-pelvis CT, the rate of missed injury has been reported to be extremely low (<0.06 percent) with a negative LR of 0.034 (0.017-0.068) [46].

The increased use and accuracy of CT have contributed to a shift to nonoperative management and reduced morbidity for many patients with BAT. CT is generally reserved for patients who are hemodynamically stable and at low risk of acutely decompensating while in the CT scanner. However, if CT is readily available (eg, within or immediately adjacent to the ED), it may be a reasonable study for some hemodynamically unstable patients [47-49].

Given the significant radiation exposure and expense associated with CT, clinicians should select the BAT patients most likely to benefit and avoid unnecessary studies. Observational studies report a low rate of positive CT scans among BAT patients [50], suggesting that many studies are unnecessary. In a prospective study involving nearly 5000 patients with blunt torso trauma, the number of patients identified with intra-abdominal injuries requiring surgery was below 5 percent [51]. A retrospective study of 147 blunt trauma patients presenting with low-risk mechanisms of injury (fall from standing, seated position, or from bed) in combination with an unremarkable physical examination (normal mental status, no chest or abdominal pain, no shortness of breath, and no tenderness on examination) reported a very low likelihood of positive findings on CT of the chest or abdomen [52]. The clinical features most strongly associated with intra-abdominal injury (and which warrant investigation with CT) as well as those unlikely to be associated with clinically significant injury are described above. (See 'Initial assessment and physical examination' above.)

More liberal use of CT is reasonable when evaluating older adults with abdominal trauma, in whom symptoms and signs of injury are often attenuated and the physical examination less accurate. In some older adults, cognitive impairment makes assessment difficult, and advanced imaging is warranted when this approach is consistent with the goals of care. (See "Geriatric trauma: Initial evaluation and management".)

CT scanning's benefits include:

●Noninvasive and fast

●Better defines organ injury and potential for nonoperative management of splenic and liver injuries [53,54]

●Detects not only the presence but the source and amount of hemoperitoneum

●Active bleeding often detectable

●Retroperitoneum and vertebral column can be assessed in conjunction with intra-abdominal structures

●Additional imaging can be performed when needed (eg, head, cervical spine, chest, pelvis)

●Patients with negative imaging are at low risk for clinically significant injuries

CT scanning's disadvantages include:

●Despite improvements in resolution, remains a relatively low-sensitivity test for mesenteric, bowel, and pancreatic duct injuries [55-59]

●IV contrast is needed; oral contrast is not needed for initial studies as it rarely adds to diagnostic accuracy and may delay imaging [60,61]

●Relatively high cost

●Can be unobtainable or delay critical care for unstable patients [62]

●Radiation exposure (see "Radiation-related risks of imaging")

CT protocols for trauma — Trauma CT protocols are designed to maximize the detection of injury. During a multiphasic CT study for abdominal trauma, images are obtained rapidly, and typically a single bolus of IV contrast is given, allowing identification and characterization of injuries to the vasculature, solid organs, and genitourinary system. Occasionally, a split bolus technique involving two or three boluses of contrast given sequentially prior to imaging is used to improve the injury detection rate [63].

CT arteriogram of the abdomen and pelvis is performed to look for active arterial bleeding or vascular injury such as occlusion or pseudoaneurysm. CTA of the abdomen has been shown to detect more splenic vascular and pelvic injuries [64,65].

CT urography requires delayed imaging, at least five minutes after contrast injection, of the abdomen and pelvis to capture the excretory phase and improve visualization of both the upper and lower urinary tracts [41]. (See "Blunt genitourinary trauma: Initial evaluation and management", section on 'Diagnostic tests'.)

Some advocate obtaining comprehensive whole-body CT imaging ("pan scan") following significant abdominal trauma. The issue of comprehensive scanning in trauma is discussed separately. (See "Initial management of trauma in adults", section on 'Computed tomography, including total body CT'.)

Ultrasound — Bedside ultrasound is an integral component of trauma management used primarily to detect free intraperitoneal blood after blunt trauma. The trauma ultrasound examination focuses on dependent intraperitoneal sites where blood is most likely to accumulate: the hepatorenal space (Morison pouch) (image 6), the splenorenal recess (image 7), and the inferior portion of the peritoneal cavity (including pouch of Douglas). These studies, when combined with evaluation of the pericardium (which must not be neglected in the setting of BAT), are referred to as the focused assessment with sonography for trauma (FAST) exam. The use of the FAST exam in the management of patients with abdominal trauma, and studies pertaining to such use, are discussed in detail separately. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

Limitations of ultrasound in the setting of BAT include:

●Injury to solid parenchyma, retroperitoneum, or diaphragm not well seen

●Uncooperative patients, obesity, bowel gas, and subcutaneous air interfere with image quality

●Low sensitivity compared with CT, particularly in the absence of hemoperitoneum and for nonhypotensive patients; cannot reliably exclude clinically significant injuries [66,67]

●Does not appear to improve diagnostic yield following negative CT [68]

●Blood cannot be distinguished from ascites or urine

●Subcapsular kidney injuries cannot be detected

●Insensitive for detecting bowel injury

●May be less sensitive than plain radiograph for detecting pneumothorax in the context of blunt trauma (see "Emergency ultrasound in adults with abdominal and thoracic trauma", section on 'Blunt thoracic trauma')

Angiography — Unstable patients with BAT and a pelvic fracture may benefit from angiography, although the order and timing of angiographic embolization versus laparotomy with preperitoneal packing remains a matter of debate. Angiography can be used to manage hemorrhage from solid viscera (eg, spleen) and to embolize bleeding pelvic vessels, but it is time consuming and requires coordination with interventional radiology services, which may not be immediately available at a given institution. (See "Severe pelvic fracture in the adult trauma patient" and "Management of splenic injury in the adult trauma patient", section on 'Splenic embolization' and "Management of hepatic trauma in adults", section on 'Hepatic embolization'.)

Diagnostic peritoneal lavage — DPL, formerly a mainstay in the diagnosis and management of BAT, has been almost entirely replaced by ultrasound and multidetector CT scanning. As the role of nonoperative management and selective embolization for abdominal injuries has expanded, the importance of DPL in modern trauma care has dramatically declined, particularly with BAT. The procedure may be necessary in some cases, such as the hypotensive BAT patient with equivocal results on FAST examination and multiple potential sources of blood loss, and in resource-poor settings where advanced imaging is unavailable. The role and performance of DPL are discussed separately. (See "Initial evaluation and management of abdominal stab wounds in adults", section on 'Diagnostic peritoneal tap and diagnostic peritoneal lavage'.)

MANAGEMENT BY CLINICAL SCENARIO

Overview — Patients with blunt abdominal trauma (BAT) require expeditious evaluation to determine the need for operative care. After providing initial resuscitation and management based upon advanced trauma life support (ATLS) protocols, emergency clinicians determine the need for laparotomy or interventional radiology using some combination of physical examination, ultrasound, computed tomography (CT), and possibly diagnostic peritoneal tap (DPT) and/or diagnostic peritoneal lavage (DPL). In some instances, such as patients with a severe pelvic fracture, angiography may be necessary to control hemorrhage and stabilize the patient [69]. A basic algorithm for the management of BAT is provided (algorithm 1). (See "Initial management of trauma in adults", section on 'Primary evaluation and management'.)

Hemodynamically unstable patient — In the unstable patient with BAT, management hinges on determining the presence or absence of intraperitoneal hemorrhage. Immediate trauma surgery consultation is required if the surgeon is not already at the bedside. A focused assessment with sonography for trauma (FAST) exam should be performed on all hemodynamically unstable BAT patients as part of their initial evaluation, assuming ultrasound is available. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

Unstable patients with a positive FAST exam typically go directly to the operating room for emergency laparotomy. If the FAST exam is limited (eg, poor image quality) and the patient is unstable, the surgeon must decide whether suspicion for intra-abdominal injury is sufficiently high to warrant emergency laparotomy. DPL has been replaced almost entirely by the combination of ultrasound and CT, owing to their speed, sensitivity, and noninvasiveness. We suggest CT to evaluate for intra-abdominal (as well as extra-abdominal) injuries in patients who can be resuscitated adequately to undergo scanning [47-49]. If this cannot be accomplished, an adequate FAST exam cannot be done, and clinicians choose to perform a DPT or DPL, most experts agree that the aspiration of 10 mL of gross blood confirms the presence of a significant intra-abdominal wound that warrants emergency laparotomy. (See "Initial evaluation and management of abdominal stab wounds in adults", section on 'Diagnostic peritoneal tap and diagnostic peritoneal lavage'.)

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used as a therapeutic adjunct in the management of some unstable BAT patients. While promising in that it can be performed at the bedside as a bridging therapy to control noncompressible hemorrhage, REBOA is associated with higher mortality and higher rates of acute kidney injury and lower extremity amputation in some studies [70]. REBOA is discussed in detail separately. (See "Endovascular methods for aortic control in trauma", section on 'Potential indications'.)

In unstable patients with no evidence of intra-abdominal injury (negative FAST exam, negative abdominal CT), clinicians must search for alternative sites of hemorrhage or other nonhemorrhagic causes of shock. (See "Approach to shock in the adult trauma patient".)

When managing an unstable trauma patient with a major pelvic fracture, clinicians should note that ultrasound cannot distinguish between blood and urine in the peritoneal cavity. If the patient can be stabilized, further evaluation of the intra-abdominal cavity with CT may be warranted. (See 'Pelvic fracture' below.)

Hemodynamically stable patient

Approach — Management of the hemodynamically stable patient with BAT depends upon the clinician's assessment of their risk for significant intra-abdominal injury. The approach selected will vary depending upon many factors, including patient age and comorbidities, mechanism of injury, examination findings, and hospital resources. In general, we follow the approach outlined immediately below but recognize that any basic plan must be adapted to clinical circumstances.

If there are significant concerns about intra-abdominal injury, we typically obtain a plain chest radiograph and basic laboratory tests (ie, complete blood count, basic liver function tests, urinalysis) in addition to abdominal imaging. Furthermore, we have a low threshold for admission and monitoring if clinical concern for intra-abdominal injury persists even in the face of unremarkable test and imaging results. (See 'Laboratory tests' above.)

●Low-risk patients and observation period – For patients deemed low risk by clinical presentation (eg, healthy, low-energy mechanism), vital signs, and laboratory tests (no anemia, no elevated transaminase concentrations [if obtained], and no hematuria), a brief period of observation (eg, a few hours) that includes serial vital signs and abdominal examinations is generally sufficient to identify those with occult intra-abdominal injury. While observation periods as long as nine hours have been described in the literature, this is impractical in busy emergency departments (EDs), and the large majority of intra-abdominal injuries become clinically apparent within one hour [71]. Patients who develop concerning signs or symptoms during their period of observation or who have abnormal laboratory findings or plain radiographs should receive CT imaging.

Ultrasound may be incorporated into the serial assessments, although the extent to which it adds to the diagnosis of intra-abdominal injury in low-risk patients remains unclear. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

For patients at low risk for intra-abdominal injury, including those with a negative abdominal CT scan, a brief observation period is reasonable in many cases, but there is as yet no high-quality evidence to support this approach. Such decisions must be made by the clinician on a case-by-case basis using their clinical judgement. Before discharge, all patients should demonstrate their ability to ambulate as they do normally and to take oral liquids, be instructed to return to the ED immediately for any concerning symptom (such as new or worsening abdominal pain), and be informed about the limitations of the CT scan for diagnosing injury.

●One or more concerning laboratory findings – For patients without a high-risk clinical presentation but with an abnormal plain chest radiograph or laboratory findings associated with intra-abdominal injury (hematocrit <30 percent, aspartate aminotransferase [AST] or alanine aminotransferase [ALT] >130 units/L, microscopic hematuria >25 red blood cells per high-power field), we obtain CT of the abdomen and pelvis with intravenous (IV) contrast. CT is the preferred modality for identifying such injuries. If a CT is obtained and is negative, a brief period of observation (eg, a few hours) that includes serial vital signs and abdominal examinations is generally sufficient to identify patients with injuries that CT may have missed (eg, bowel injury). For patients with persistent pain or tenderness or those who fail a trial of ambulation or oral intake despite a negative CT, admission for observation and surgical consultation is warranted.

●One or more concerning findings in presentation or examination – For patients who are hemodynamically stable but whose presentation or examination includes one or more findings associated with an increased risk for intra-abdominal injury, we obtain CT of the abdomen and pelvis with IV contrast. Concerning findings sufficient to prompt imaging may include persistent abdominal or flank discomfort or vital sign abnormalities.

Patients with negative CT imaging are at low risk for clinically significant intra-abdominal injuries, and most can be discharged home. Patients with persistent pain or tenderness despite a negative CT should be admitted for observation. Surgical consultation is warranted in these cases, and repeat imaging may be necessary. High-risk examination findings are reviewed above and include the following: hypotension, peritoneal signs (eg, abdominal guarding, rebound tenderness), abdominal distension, and seatbelt sign. (See 'Initial assessment and physical examination' above.)

●Whole-body imaging – Whether routine whole-body imaging with CT leads to better outcomes among high-risk patients than selective imaging (ie, directed by clinical suspicion) is controversial. This issue is reviewed separately. (See "Initial management of trauma in adults", section on 'Computed tomography, including total body CT'.)

Diagnostic imaging or serial physical examination — Evaluation of the hemodynamically stable patient with BAT incorporates diagnostic imaging studies, serial physical examinations, or both. Each method of patient evaluation has limitations, and there are a number of reasonable approaches.

In the stable BAT patient, ultrasound may miss clinically relevant injuries, and we do not advocate its use as a single definitive screening test in this patient population [66,72]. The accuracy of ultrasound evaluation for detecting intra-abdominal injury improves with serial examinations [73]. If an ultrasound examination is performed and detects intraperitoneal blood, the patient should undergo abdominal and pelvic CT with IV contrast to delineate intraperitoneal injuries and quantify the hemoperitoneum. The surgeon may choose either admission with nonoperative management or immediate laparotomy depending upon the injuries detected and the patient's clinical status.

We perform abdominal and pelvic CT with IV contrast in any patient with one or more high-risk clinical findings and in any patient with persistent abdominal pain or tenderness on serial examinations (eg, persistent tenderness on exams performed 30 minutes apart). CT may also be needed for patients who are hemodynamically stable but whose sensorium or reliability is altered by closed head injury, drug or alcohol intoxication, or significant distracting injury.

The decision of whether to perform CT early or follow the patient with serial physical examinations is made largely on clinical grounds. Serial physical examination is reserved for the patient whose examination is deemed reliable (ie, patients with a normal sensorium and no severe distracting injury). While radiation from contemporary scanners has been reduced, concerns about exposure remain. Some trauma centers are making increased use of serial examinations and standardized clinical assessments [51]. (See "Radiation-related risks of imaging".)

Serial abdominal examinations and serial ultrasound evaluations may be useful in select hemodynamically stable BAT patients. As an example, a nonintoxicated patient who is not an older adult and manifests no gross neurologic abnormalities (normal Glasgow Coma Scale score) or high-risk clinical features would be a suitable candidate for observation with serial assessments.

Clinical assessment of an alert, nonintoxicated BAT patient that depends solely on abdominal examination findings is not infallible [27,74]. One prospective observational study of such patients, with no signs of external trauma and a normal abdominal examination, found clinically significant abnormalities in 7.1 percent of patients using CT findings as the gold standard [22]. The use and limitations of the abdominal examination in BAT are discussed further above. (See 'Initial assessment and physical examination' above.)

The accuracy of serial examinations continues to be debated, as has the period of observation necessary to identify significant intra-abdominal injuries. While a strategy of serial observation requires careful selection of patients in whom reliable examinations can be performed, the results of several observational studies suggest that this approach is safe and feasible in patients deemed to be at low risk by virtue of their initial vital signs, diagnostic studies, and signs and symptoms [71,75].

Clinical indications for laparotomy — Nonoperative management has become standard for all but the most severely injured BAT patients. Immediate laparotomy after injury from a blunt mechanism is rarely based solely on clinical parameters. Potential indications include the following:

●Unexplained signs of blood loss or hypotension in a patient who cannot be stabilized and in whom intra-abdominal injury is strongly suspected

●Clear and persistent signs of peritoneal irritation

●Radiologic evidence of pneumoperitoneum consistent with a viscus rupture

●Evidence of a diaphragmatic rupture

●Persistent, significant gastrointestinal bleeding seen in nasogastric drainage or vomitus

Establishing the need for urgent celiotomy on clinical grounds is particularly problematic in the patient with multiple blunt injuries. Numerous extra-abdominal sources of hemorrhage may exist. Head injury or intoxication often coexist with abdominal trauma, further impairing the reliability of examination findings. Laparotomy may imperil the patient when more crucial diagnostic and therapeutic steps are delayed. Where confusion exists, we strongly prefer that corroborative diagnostic tests be performed.

Special considerations

Pelvic fracture — In patients with a pelvic fracture and evidence of ongoing bleeding (ie, hemodynamic instability), the presence or absence of hemoperitoneum determines management. Detection of free fluid by ultrasound or gross intraperitoneal blood by DPT accurately predicts active intraperitoneal hemorrhage and the need for emergency laparotomy [72,76,77]. The absence of intraperitoneal blood as determined by ultrasound or DPT suggests major retroperitoneal hemorrhage, assuming there is no extra-abdominal source of bleeding. (See "Pelvic trauma: Initial evaluation and management".)

There is an important exception when intraperitoneal fluid detected by ultrasound does not represent hemorrhage. Major pelvic fracture can be associated with intraperitoneal bladder rupture. In such cases, the free intraperitoneal fluid found on ultrasound is uroperitoneum rather than hemoperitoneum. Intraperitoneal bladder rupture requires surgical repair.

Patients with a major pelvic fracture are at risk for life-threatening retroperitoneal hemorrhage. As such, some clinicians perform a DPT in the hemodynamically unstable patient with major pelvic fracture and a positive ultrasound in order to distinguish hemoperitoneum (which requires exigent laparotomy) from uroperitoneum and to help decide whether to perform diagnostic and potentially therapeutic pelvic angiography as the next step. Urgent laparotomy for bladder repair is performed thereafter.

After carefully examining the perineum and rectum, clinicians should place a pelvic stabilization device (prefabricated pelvic binder or a bed sheet tied tightly around the pelvis) on any potentially unstable pelvic fracture that may be contributing to hemodynamic instability (image 8). External fixation devices are generally placed in the operating room because placement can be difficult and time consuming and may interfere with other components of resuscitation. Following stabilization with pelvic angiography and embolization, abdominal CT may be used to look further for intraperitoneal injury.

Multiple-system injury — Clinicians cannot approach the management of the abdominal trauma patient with more than one life-threatening injury dogmatically. At major trauma centers, clinicians regularly confront the problem of intraperitoneal hemorrhage in a patient with apparent closed head injury and suspected blunt aortic disruption. Traditionally, laparotomy to control intraperitoneal hemorrhage takes precedence over operative management of head or chest trauma. However, these situations are complex, and decision-making is influenced by numerous dynamic variables. In general, a patient with known hemoperitoneum who cannot be stabilized must first undergo laparotomy for lifesaving hemostasis before other injuries are addressed.

Closed head injury — In patients presenting with BAT and concomitant closed head injury, the necessity and timing of neurosurgical intervention is directed by the patient's neurologic examination (Glasgow Coma Scale, presence of lateralizing neurologic signs) and CT imaging results. Immediate consultation with a neurosurgeon and trauma surgeon is needed [78]. It is uncommon for both laparotomy and craniotomy to be necessary; in unstable patients, laparotomy generally takes precedence. (See "Management of acute moderate and severe traumatic brain injury".)

Patient transfer — A trauma patient at a small rural hospital may need a laparotomy for hemorrhage control before being transferred to a trauma center for definitive care [79]. Consultation with the trauma center should begin as soon as it is apparent the patient has sustained injuries beyond the management capacity of the hospital. (See "Initial management of trauma in adults", section on 'Patient transfer'.)

Pregnant patient — Trauma remains the most common nonobstetric cause of maternal death during pregnancy and has been reported to complicate 6 to 7 percent of pregnancies. Initial evaluation and management of the pregnant trauma patient is directed at determining the extent of maternal injury and directing resuscitation towards the mother's survival. Management of the pregnant trauma patient is discussed separately. (See "Initial evaluation and management of major trauma in pregnancy".)

Geriatric patient — Patterns of trauma in older adults are similar to those of adults in general. However, the signs and symptoms of abdominal injury are often attenuated in adults over 60 years, and therefore, clinicians must maintain a high index of suspicion for injuries in this population. (See "Geriatric trauma: Initial evaluation and management".)

Obese patient — A retrospective trauma data bank study of over 100,000 BAT patients found that class III obesity (body mass index [BMI] >40) was associated with a lower rate of hollow viscus injury [80]. However, rates of abdominal solid organ injury are comparable, and the extended FAST (e-FAST) and physical examinations are less accurate in obese patients [81,82]. Given these findings, we maintain a low threshold for obtaining CT imaging in obese patients with BAT.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues of trauma management in adults" and "Society guideline links: Thoracic trauma" and "Society guideline links: Traumatic abdominal and non-genitourinary retroperitoneal injury" and "Society guideline links: Thoracic and lumbar spine injury in adults".)

SUMMARY AND RECOMMENDATIONS

●Approach and management algorithm – Emergency clinicians managing blunt trauma must maintain a high degree of clinical suspicion for intra-abdominal injury, particularly in patients with suggestive mechanisms, signs of external trauma, or an altered sensorium due to head injury or intoxication. Prompt resuscitation of the unstable patient is performed in parallel with physical examination and diagnostic testing to determine the presence or absence of hemoperitoneum and organ injury. A basic algorithm for the management of blunt abdominal trauma is provided (algorithm 1).

●Epidemiology – Motor vehicle collision is the most common cause of blunt abdominal trauma (BAT). The spleen and liver are the most commonly injured solid organs. Delayed splenic rupture can occur. Injuries to the pancreas, bowel, mesentery, and diaphragm are less common but potentially dangerous and more difficult to diagnose than solid organ injury. (See 'Epidemiology' above and 'Mechanism of injury' above.)

●History – Noteworthy aspects of the history include (see 'History' above):

•Fatality at the scene

•Vehicle type and velocity

•Whether the vehicle rolled over

•Patient's location within the vehicle

•Extent of intrusion into the passenger compartment

•Extent of damage to the vehicle; steering wheel deformity

•Whether seatbelts were used and what type (unrestrained victims are at higher risk of injury); whether air bags deployed

●Clinical presentation and physical examination – The clinical presentation of BAT varies widely, from minor complaints to severe shock. The accuracy of the physical examination is limited. The initial presentation may be benign despite the presence of major intra-abdominal injury. Clinicians must look for intra-abdominal injury in all BAT patients with an altered sensorium or extra-abdominal injuries. Examination findings associated with intra-abdominal injury include:

•Seatbelt sign (picture 1), particularly if above the level of the anterior-superior iliac spine (ASIS)

•Rebound tenderness

•Hypotension

•Abdominal distension

•Abdominal guarding

•Severe distracting injury (eg, femur fracture)

The absence of such findings does not exclude intra-abdominal injury. If the patient is awake, alert, hemodynamically stable, and free of abdominal pain or tenderness, intra-abdominal injury is unlikely. (See 'Initial assessment and physical examination' above.)

The signs and symptoms of abdominal injury are often attenuated in adults over 60 years; clinicians must maintain a high index of suspicion for injuries in this population. (See "Geriatric trauma: Initial evaluation and management".)

Pedestrians often sustain a triad of injuries to the leg, torso, and cranium; injury to any of these sites should prompt careful evaluation of the others.

●Blood transfusion and laboratory testing – Notify the blood bank immediately and directly (ie, by telephone or in person) of the need for transfusion should a BAT patient present with life-threatening bleeding. Order a blood type and screen for any victim of significant trauma.

Routine hematology and chemistry laboratory tests are of limited value in the management of acute trauma but may be helpful in identifying patients at low risk for significant injury when used in combination with other clinical findings. We suggest obtaining a microscopic urinalysis in victims of BAT when the presence of intra-abdominal injury is unclear, as microscopic hematuria (>25 red blood cells per high-power field) increases the likelihood of significant intra-abdominal injury. (See 'Laboratory tests' above and "Approach to shock in the adult trauma patient".)

●Diagnostic imaging – The trauma patient must be stabilized before most abdominal radiographic studies (eg, computed tomography [CT]) can be performed. Clinicians must guard against exacerbating spinal injury when positioning patients for imaging studies. Patients must be closely monitored while in the radiology area. The indications, advantages, and disadvantages of the major modalities for imaging BAT are discussed above. (See 'Imaging studies' above.)

●Hemodynamically unstable patient – In the hemodynamically unstable patient, management hinges on determining the presence or absence of intraperitoneal hemorrhage (algorithm 1). The emergency clinician performs a focused abdominal ultrasound exam (or, in unusual instances, a diagnostic peritoneal tap [DPT]) to make this determination. Hemoperitoneum in the clinically unstable patient without other apparent injury mandates laparotomy. For patients without hemoperitoneum, clinicians search for extra-abdominal sites of hemorrhage. (See 'Hemodynamically unstable patient' above and 'Clinical indications for laparotomy' above and 'Diagnostic peritoneal lavage' above.)

●Hemodynamically stable patient – Management of the hemodynamically stable patient depends upon the clinician's assessment of their risk for significant injury. Patients at increased risk based upon their presentation, examination findings, or laboratory study results are evaluated by CT. Several approaches may be used to assess low-risk patients, and these are described in the text (algorithm 1). (See 'Hemodynamically stable patient' above.)

●Consultation and transfer – Prompt consultation with a trauma center is paramount for those patients with severe BAT presenting to a small emergency department without the capacity to manage such injuries. (See "Initial management of trauma in adults", section on 'Patient transfer'.)