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Emergency and Acute Medicine – Imaging in Abdominal Trauma
Overview
Imaging plays a central role in the evaluation of abdominal trauma and must be guided by the patient’s history, physical examination, and—most importantly—hemodynamic status. Abdominal trauma occurs across a broad spectrum, ranging from isolated abdominal injury to severe multisystem trauma. Injuries are categorized as blunt or penetrating, with penetrating trauma further subdivided into stab wounds and gunshot wounds. Hemodynamic stability is the key determinant in selecting appropriate imaging and procedural strategies. Unstable patients generally require rapid surgical decision-making, whereas many stable patients can be managed nonoperatively with careful imaging and observation.
Clinical Assessment
History should focus on the mechanism of injury, use of restraints, airbags or helmets, prehospital vital signs, mental status at the scene, and any change in mental status. A complete AMPLE history is essential, including allergies (especially to medications or contrast), current medications, past medical and surgical history, last oral intake, and events leading up to the injury.
Physical examination begins with an ABCDE survey (Airway, Breathing, Circulation, Disability, Exposure), followed by full exposure of the patient and careful palpation of all abdominal quadrants. Abdominal injury is identified in only about half of trauma patients, and the physical exam may be unreliable in intoxicated, uncooperative, or multisystem trauma patients.
General Imaging Strategy
All trauma patients are initially managed using the ABCDE approach. Imaging decisions are then tailored according to stability.
Unstable Trauma Patients
Hemodynamically unstable patients should undergo immediate bedside ultrasonography as part of the primary survey. A positive FAST examination strongly suggests intra-abdominal bleeding as the cause of hypotension. A negative FAST raises concern for alternative bleeding sources, including retroperitoneal hemorrhage, pelvic fractures, thoracic bleeding, or significant blood loss prior to arrival. Surgical consultation should be obtained immediately to prepare for definitive operative management.
Stable Trauma Patients
In stable patients, three principal diagnostic modalities are used to define the extent of abdominal injury.
Ultrasound is often the initial screening test. A positive study in a stable patient raises concern for potential deterioration and should prompt rapid CT imaging and surgical consultation.
CT scanning is the definitive diagnostic tool in stable abdominal trauma. It provides superior detection of solid organ and retroperitoneal injuries compared with ultrasound and helps determine whether nonoperative management or interventional radiology techniques, such as embolization, are appropriate. CT is indicated in all stable patients with stab wounds and in patients with gross hematuria to evaluate for renal injury.
Diagnostic peritoneal lavage is now infrequently used, having largely been replaced by ultrasound and CT.
Laboratory Evaluation
Initial laboratory studies include blood type and screen, complete blood count, electrolytes, creatinine, lipase, urinalysis, and electrocardiography when indicated. These tests support imaging findings and assist in identifying associated injuries or complications.
Ultrasound (FAST Examination)
The FAST exam evaluates dependent intraperitoneal spaces where free fluid accumulates, including the hepatorenal recess (Morison pouch), splenorenal space, suprapubic region, and pericardium.
Advantages include rapid bedside performance, noninvasiveness, lack of radiation or contrast, and repeatability during resuscitation.
Limitations include operator dependence and poor sensitivity for solid organ parenchymal injuries, retroperitoneal bleeding, bowel injury, and hemorrhage associated with pelvic fractures.
A positive study is defined by visualization of free fluid or obvious organ injury. Adequate evaluation requires views of the right upper quadrant, left upper quadrant, pelvis, and heart.
Computed Tomography (CT)
CT scanning has a sensitivity of approximately 85–98% for abdominal trauma and provides detailed anatomic information about organ injury. It supports nonoperative management strategies and allows evaluation of the spine and adjacent structures.
Disadvantages include cost, radiation exposure, and the need for intravenous contrast, which carries a risk of allergic reaction and nephrotoxicity. Certain injuries—such as isolated diaphragmatic, pancreatic, or bowel injuries—may be missed early after trauma.
CT is indicated in hemodynamically stable patients and is contraindicated in unstable patients or those who already require emergent laparotomy. Many centers now use a “pan-scan” approach in multisystem trauma, though this increases cumulative radiation exposure.
Angiography
Angiography is useful for identifying and embolizing bleeding vessels, particularly in patients with pelvic fractures or solid organ hemorrhage. It may be used in selected unstable patients when surgical control is not immediately feasible.
Diagnostic Peritoneal Lavage (DPL)
DPL is invasive but highly sensitive for detecting intra-abdominal bleeding, mesenteric injury, and hollow viscus injury. It is now reserved for select situations, such as unstable patients with equivocal ultrasound findings or those requiring emergent surgery for another indication.
A positive test includes aspiration of blood, bile, bowel contents, or urine, or elevated red blood cell counts depending on the mechanism of injury. Contraindications include clear indications for laparotomy, and relative contraindications include prior abdominal surgery, pregnancy, and pediatric patients.
Disposition and Follow-Up
All unstable trauma patients require admission and frequently operative management. Most patients with multisystem trauma and abdominal involvement should be admitted. Pregnant patients beyond 24 weeks’ gestation require hospital admission for fetal–maternal monitoring.
Stable patients may be discharged only after a negative evaluation, sustained hemodynamic stability, and assurance of reliable follow-up and access to emergency care.
Discharge Advice and Safety Netting
Patients discharged after abdominal trauma must be instructed to return immediately for worsening abdominal pain, distention, vomiting, rectal bleeding, or any new concerning symptoms, as intestinal and pancreatic injuries may present late.
Clinical Pearls and Pitfalls
Bedside ultrasound can be performed immediately during resuscitation and repeated if clinical status changes. Increasing reliance on CT has reduced missed injuries but also increased radiation exposure and lifetime cancer risk. Diagnostic peritoneal lavage and local wound exploration are now less commonly used. Common pitfalls include failure to obtain early blood typing and pregnancy testing, and discharging pregnant patients beyond 24 weeks without appropriate monitoring.
Overview
Imaging plays a central role in the evaluation of abdominal trauma and must be guided by the patient’s history, physical examination, and—most importantly—hemodynamic status. Abdominal trauma occurs across a broad spectrum, ranging from isolated abdominal injury to severe multisystem trauma. Injuries are categorized as blunt or penetrating, with penetrating trauma further subdivided into stab wounds and gunshot wounds. Hemodynamic stability is the key determinant in selecting appropriate imaging and procedural strategies. Unstable patients generally require rapid surgical decision-making, whereas many stable patients can be managed nonoperatively with careful imaging and observation.
Clinical Assessment
History should focus on the mechanism of injury, use of restraints, airbags or helmets, prehospital vital signs, mental status at the scene, and any change in mental status. A complete AMPLE history is essential, including allergies (especially to medications or contrast), current medications, past medical and surgical history, last oral intake, and events leading up to the injury.
Physical examination begins with an ABCDE survey (Airway, Breathing, Circulation, Disability, Exposure), followed by full exposure of the patient and careful palpation of all abdominal quadrants. Abdominal injury is identified in only about half of trauma patients, and the physical exam may be unreliable in intoxicated, uncooperative, or multisystem trauma patients.
General Imaging Strategy
All trauma patients are initially managed using the ABCDE approach. Imaging decisions are then tailored according to stability.
Unstable Trauma Patients
Hemodynamically unstable patients should undergo immediate bedside ultrasonography as part of the primary survey. A positive FAST examination strongly suggests intra-abdominal bleeding as the cause of hypotension. A negative FAST raises concern for alternative bleeding sources, including retroperitoneal hemorrhage, pelvic fractures, thoracic bleeding, or significant blood loss prior to arrival. Surgical consultation should be obtained immediately to prepare for definitive operative management.
Stable Trauma Patients
In stable patients, three principal diagnostic modalities are used to define the extent of abdominal injury.
Ultrasound is often the initial screening test. A positive study in a stable patient raises concern for potential deterioration and should prompt rapid CT imaging and surgical consultation.
CT scanning is the definitive diagnostic tool in stable abdominal trauma. It provides superior detection of solid organ and retroperitoneal injuries compared with ultrasound and helps determine whether nonoperative management or interventional radiology techniques, such as embolization, are appropriate. CT is indicated in all stable patients with stab wounds and in patients with gross hematuria to evaluate for renal injury.
Diagnostic peritoneal lavage is now infrequently used, having largely been replaced by ultrasound and CT.
Laboratory Evaluation
Initial laboratory studies include blood type and screen, complete blood count, electrolytes, creatinine, lipase, urinalysis, and electrocardiography when indicated. These tests support imaging findings and assist in identifying associated injuries or complications.
Ultrasound (FAST Examination)
The FAST exam evaluates dependent intraperitoneal spaces where free fluid accumulates, including the hepatorenal recess (Morison pouch), splenorenal space, suprapubic region, and pericardium.
Advantages include rapid bedside performance, noninvasiveness, lack of radiation or contrast, and repeatability during resuscitation.
Limitations include operator dependence and poor sensitivity for solid organ parenchymal injuries, retroperitoneal bleeding, bowel injury, and hemorrhage associated with pelvic fractures.
A positive study is defined by visualization of free fluid or obvious organ injury. Adequate evaluation requires views of the right upper quadrant, left upper quadrant, pelvis, and heart.
Computed Tomography (CT)
CT scanning has a sensitivity of approximately 85–98% for abdominal trauma and provides detailed anatomic information about organ injury. It supports nonoperative management strategies and allows evaluation of the spine and adjacent structures.
Disadvantages include cost, radiation exposure, and the need for intravenous contrast, which carries a risk of allergic reaction and nephrotoxicity. Certain injuries—such as isolated diaphragmatic, pancreatic, or bowel injuries—may be missed early after trauma.
CT is indicated in hemodynamically stable patients and is contraindicated in unstable patients or those who already require emergent laparotomy. Many centers now use a “pan-scan” approach in multisystem trauma, though this increases cumulative radiation exposure.
Angiography
Angiography is useful for identifying and embolizing bleeding vessels, particularly in patients with pelvic fractures or solid organ hemorrhage. It may be used in selected unstable patients when surgical control is not immediately feasible.
Diagnostic Peritoneal Lavage (DPL)
DPL is invasive but highly sensitive for detecting intra-abdominal bleeding, mesenteric injury, and hollow viscus injury. It is now reserved for select situations, such as unstable patients with equivocal ultrasound findings or those requiring emergent surgery for another indication.
A positive test includes aspiration of blood, bile, bowel contents, or urine, or elevated red blood cell counts depending on the mechanism of injury. Contraindications include clear indications for laparotomy, and relative contraindications include prior abdominal surgery, pregnancy, and pediatric patients.
Disposition and Follow-Up
All unstable trauma patients require admission and frequently operative management. Most patients with multisystem trauma and abdominal involvement should be admitted. Pregnant patients beyond 24 weeks’ gestation require hospital admission for fetal–maternal monitoring.
Stable patients may be discharged only after a negative evaluation, sustained hemodynamic stability, and assurance of reliable follow-up and access to emergency care.
Discharge Advice and Safety Netting
Patients discharged after abdominal trauma must be instructed to return immediately for worsening abdominal pain, distention, vomiting, rectal bleeding, or any new concerning symptoms, as intestinal and pancreatic injuries may present late.
Clinical Pearls and Pitfalls
Bedside ultrasound can be performed immediately during resuscitation and repeated if clinical status changes. Increasing reliance on CT has reduced missed injuries but also increased radiation exposure and lifetime cancer risk. Diagnostic peritoneal lavage and local wound exploration are now less commonly used. Common pitfalls include failure to obtain early blood typing and pregnancy testing, and discharging pregnant patients beyond 24 weeks without appropriate monitoring.
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