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Emergency and Acute Medicine – Blunt Abdominal Trauma
Overview and Mechanism of Injury
Blunt abdominal trauma results from a sudden transfer of force or pressure to the abdomen. Injury to solid organs most commonly presents with hemorrhage, whereas damage to hollow viscus organs leads to bleeding and peritonitis due to leakage of bowel contents. The clinical impact depends on the magnitude of force, organs involved, and associated injuries.
Etiology and Patterns of Injury
Motor vehicle collisions account for approximately 60% of blunt abdominal trauma cases. Solid organs are injured more often than hollow organs. The spleen is the most frequently affected organ, followed by the liver, intestines, retroperitoneal structures, and kidneys. Less commonly involved structures include the mesentery, pancreas, diaphragm, urinary bladder, urethra, and major vascular structures.
Pediatric Considerations
Children often appear to tolerate blunt trauma better due to the increased elasticity of their tissues. However, because the liver and spleen extend beyond the protective rib cage in children, these organs are more exposed and vulnerable to injury. As a result, significant intra-abdominal injury may occur despite minimal external signs.
Clinical Presentation
Symptoms range widely from mild abdominal discomfort to overt peritoneal irritation and hypovolemic shock. Patients may report nausea or vomiting. Labored breathing can occur due to diaphragmatic irritation or upper abdominal injury. Left shoulder pain during inspiration (Kehr sign) suggests diaphragmatic irritation from intra-abdominal bleeding. Hollow viscus injuries, particularly small-bowel trauma, may present in a delayed fashion.
Initial Evaluation and Essential Workup
Management begins with rapid assessment and stabilization of airway, breathing, and circulation (ABCs). The primary goal is to identify patients who require urgent operative intervention.
A careful abdominal examination should assess for tenderness, distension, guarding, and signs of peritoneal irritation, while recognizing that injuries to the retroperitoneum or intrathoracic abdomen may not be detected by palpation alone. The anatomical boundaries of the abdomen extend from the diaphragm superiorly to the intragluteal folds inferiorly and include the entire circumferential torso.
The skin should be inspected for abrasions or ecchymoses, including the back, which requires rolling the patient. Seatbelt or lap-belt marks are particularly concerning for significant intra-abdominal injury. Bowel sounds may be diminished or absent, although this is a late finding.
A Foley catheter may be placed to monitor urine output if there is no blood at the urethral meatus, no perineal hematoma, and a normal prostate examination. Pelvic radiographs are useful when pelvic fracture or gross hematuria suggests genitourinary injury, prompting further evaluation with specialized imaging when indicated.
Imaging and Diagnostic Modalities
CT scanning is the most valuable tool for evaluating solid organ injury, retroperitoneal structures, and determining the need for surgery, provided the patient is hemodynamically stable enough for transport.
Focused Assessment with Sonography for Trauma (FAST) is a rapid, noninvasive bedside test used to detect free intraperitoneal fluid. While efficient, it is operator dependent.
Diagnostic peritoneal lavage (DPL) is primarily reserved for unstable patients and is especially helpful in identifying injuries within the intrathoracic abdomen, pelvis, or true abdominal cavity. A positive study includes gross blood, elevated red or white blood cell counts, or the presence of bile, feces, or food particles.
Laboratory Evaluation
Initial hemoglobin and hematocrit levels may be normal due to acute isovolemic blood loss. Blood typing and screening are essential, with cross-matching of packed red blood cells for unstable patients. Urinalysis should be performed to detect hematuria, and microscopic hematuria in the setting of shock warrants genitourinary evaluation. Arterial blood gas analysis may reveal a base deficit, indicating hypovolemia and guiding resuscitation efforts.
Differential Diagnosis
Pain from lower thoracic injuries may mimic abdominal pathology and should always be considered in the evaluation of blunt trauma patients.
Prehospital Management
Fluid resuscitation should be titrated to clinical response, with a target systolic blood pressure of 90–100 mm Hg. Normal vital signs do not exclude significant intra-abdominal injury.
Emergency Department Stabilization and Treatment
Initial stabilization focuses on securing the airway, providing high-flow oxygen, and establishing two large-bore intravenous lines for crystalloid infusion. If there is no response after 2 liters of crystalloid, packed red blood cells should be administered. In cases of profound shock, immediate transfusion with O-negative blood may be lifesaving.
A nasogastric tube may be placed to decompress the stomach, reduce distention, and lower aspiration risk, and may improve respiratory distress caused by diaphragmatic herniation of the stomach.
Medications
Tetanus prophylaxis should be administered in patients with open wounds, using tetanus toxoid and tetanus immunoglobulin when indicated. Broad-spectrum intravenous antibiotics with aerobic and anaerobic coverage, such as a second-generation cephalosporin, are recommended when contamination or hollow viscus injury is suspected.
Pediatric Resuscitation Considerations
In children with shock, crystalloid boluses are given at 20 mL/kg, and packed red blood cells are administered at 1 mL/kg when needed.
Disposition and Follow-Up
Admission is indicated for postoperative patients, those with equivocal findings on FAST, CT, or DPL, and for most blunt abdominal trauma cases requiring observation and serial abdominal examinations.
Patients in whom intra-abdominal injury is suspected should not be discharged without an adequate period of observation, even if initial imaging and examination are negative.
Clinical Pearls and Pitfalls
Do not delay blood transfusion in patients with clinical shock despite a normal hematocrit. Avoid excessive crystalloid resuscitation. Always obtain a pregnancy test in females of childbearing age. Unstable patients should never be transported to CT for diagnostic imaging.
Overview and Mechanism of Injury
Blunt abdominal trauma results from a sudden transfer of force or pressure to the abdomen. Injury to solid organs most commonly presents with hemorrhage, whereas damage to hollow viscus organs leads to bleeding and peritonitis due to leakage of bowel contents. The clinical impact depends on the magnitude of force, organs involved, and associated injuries.
Etiology and Patterns of Injury
Motor vehicle collisions account for approximately 60% of blunt abdominal trauma cases. Solid organs are injured more often than hollow organs. The spleen is the most frequently affected organ, followed by the liver, intestines, retroperitoneal structures, and kidneys. Less commonly involved structures include the mesentery, pancreas, diaphragm, urinary bladder, urethra, and major vascular structures.
Pediatric Considerations
Children often appear to tolerate blunt trauma better due to the increased elasticity of their tissues. However, because the liver and spleen extend beyond the protective rib cage in children, these organs are more exposed and vulnerable to injury. As a result, significant intra-abdominal injury may occur despite minimal external signs.
Clinical Presentation
Symptoms range widely from mild abdominal discomfort to overt peritoneal irritation and hypovolemic shock. Patients may report nausea or vomiting. Labored breathing can occur due to diaphragmatic irritation or upper abdominal injury. Left shoulder pain during inspiration (Kehr sign) suggests diaphragmatic irritation from intra-abdominal bleeding. Hollow viscus injuries, particularly small-bowel trauma, may present in a delayed fashion.
Initial Evaluation and Essential Workup
Management begins with rapid assessment and stabilization of airway, breathing, and circulation (ABCs). The primary goal is to identify patients who require urgent operative intervention.
A careful abdominal examination should assess for tenderness, distension, guarding, and signs of peritoneal irritation, while recognizing that injuries to the retroperitoneum or intrathoracic abdomen may not be detected by palpation alone. The anatomical boundaries of the abdomen extend from the diaphragm superiorly to the intragluteal folds inferiorly and include the entire circumferential torso.
The skin should be inspected for abrasions or ecchymoses, including the back, which requires rolling the patient. Seatbelt or lap-belt marks are particularly concerning for significant intra-abdominal injury. Bowel sounds may be diminished or absent, although this is a late finding.
A Foley catheter may be placed to monitor urine output if there is no blood at the urethral meatus, no perineal hematoma, and a normal prostate examination. Pelvic radiographs are useful when pelvic fracture or gross hematuria suggests genitourinary injury, prompting further evaluation with specialized imaging when indicated.
Imaging and Diagnostic Modalities
CT scanning is the most valuable tool for evaluating solid organ injury, retroperitoneal structures, and determining the need for surgery, provided the patient is hemodynamically stable enough for transport.
Focused Assessment with Sonography for Trauma (FAST) is a rapid, noninvasive bedside test used to detect free intraperitoneal fluid. While efficient, it is operator dependent.
Diagnostic peritoneal lavage (DPL) is primarily reserved for unstable patients and is especially helpful in identifying injuries within the intrathoracic abdomen, pelvis, or true abdominal cavity. A positive study includes gross blood, elevated red or white blood cell counts, or the presence of bile, feces, or food particles.
Laboratory Evaluation
Initial hemoglobin and hematocrit levels may be normal due to acute isovolemic blood loss. Blood typing and screening are essential, with cross-matching of packed red blood cells for unstable patients. Urinalysis should be performed to detect hematuria, and microscopic hematuria in the setting of shock warrants genitourinary evaluation. Arterial blood gas analysis may reveal a base deficit, indicating hypovolemia and guiding resuscitation efforts.
Differential Diagnosis
Pain from lower thoracic injuries may mimic abdominal pathology and should always be considered in the evaluation of blunt trauma patients.
Prehospital Management
Fluid resuscitation should be titrated to clinical response, with a target systolic blood pressure of 90–100 mm Hg. Normal vital signs do not exclude significant intra-abdominal injury.
Emergency Department Stabilization and Treatment
Initial stabilization focuses on securing the airway, providing high-flow oxygen, and establishing two large-bore intravenous lines for crystalloid infusion. If there is no response after 2 liters of crystalloid, packed red blood cells should be administered. In cases of profound shock, immediate transfusion with O-negative blood may be lifesaving.
A nasogastric tube may be placed to decompress the stomach, reduce distention, and lower aspiration risk, and may improve respiratory distress caused by diaphragmatic herniation of the stomach.
Medications
Tetanus prophylaxis should be administered in patients with open wounds, using tetanus toxoid and tetanus immunoglobulin when indicated. Broad-spectrum intravenous antibiotics with aerobic and anaerobic coverage, such as a second-generation cephalosporin, are recommended when contamination or hollow viscus injury is suspected.
Pediatric Resuscitation Considerations
In children with shock, crystalloid boluses are given at 20 mL/kg, and packed red blood cells are administered at 1 mL/kg when needed.
Disposition and Follow-Up
Admission is indicated for postoperative patients, those with equivocal findings on FAST, CT, or DPL, and for most blunt abdominal trauma cases requiring observation and serial abdominal examinations.
Patients in whom intra-abdominal injury is suspected should not be discharged without an adequate period of observation, even if initial imaging and examination are negative.
Clinical Pearls and Pitfalls
Do not delay blood transfusion in patients with clinical shock despite a normal hematocrit. Avoid excessive crystalloid resuscitation. Always obtain a pregnancy test in females of childbearing age. Unstable patients should never be transported to CT for diagnostic imaging.
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