What is the appropriate management for a patient with a history of blunt trauma presenting with mild abdominal tenderness?

Management of Blunt Abdominal Trauma with Mild Abdominal Tenderness

Patients with blunt abdominal trauma and mild abdominal tenderness require immediate FAST examination if hemodynamically unstable, or contrast-enhanced CT abdomen/pelvis if hemodynamically stable, as physical examination alone is unreliable and misses significant injuries in up to 19% of cases. 1

Initial Assessment and Risk Stratification

Hemodynamic Status Determines Immediate Pathway

• Hemodynamically unstable patients (systolic BP <90 mmHg) should undergo immediate FAST examination at bedside to detect free intraperitoneal fluid. 1
• If FAST shows significant free fluid in an unstable patient, proceed directly to urgent exploratory laparotomy without delay for CT imaging. 1
• Hemodynamically stable patients should proceed to contrast-enhanced CT abdomen and pelvis as the definitive diagnostic study. 1, 2

Critical Clinical Predictors to Assess

Even with "mild" tenderness, evaluate for high-risk features that mandate imaging:

• Glasgow Coma Scale score <14 (altered mental status can mask abdominal findings) 1
• Costal margin tenderness (associated with intra-abdominal injury) 1
• Hematuria ≥25 RBCs/HPF (sensitivity marker for solid organ injury) 1
• Hematocrit <30% (suggests ongoing bleeding) 1
• Femur fracture (high-energy mechanism) 1
• Abnormal chest radiograph with rib fractures or pneumothorax 1

A critical pitfall: Physical examination is notoriously unreliable in blunt trauma—19% of patients with confirmed intra-abdominal injuries have no abdominal tenderness, and 14% of patients without pain or tenderness still have positive CT findings requiring intervention. 1, 3

Definitive Imaging Strategy

CT Abdomen/Pelvis with IV Contrast is the Gold Standard

• Single-phase IV contrast-enhanced CT is the preferred protocol with 97% sensitivity and 95% specificity for detecting injuries requiring intervention. 4, 2
• CT detects solid organ injuries, bowel perforations (92-94% sensitivity), mesenteric injuries, retroperitoneal trauma, and active bleeding that FAST examination misses. 4, 2, 5
• CT changes the diagnosis in 49-51% of cases and alters management in 42% of patients with abdominal trauma. 4

FAST Examination Limitations

• FAST has only 79% sensitivity for intra-abdominal injury and misses 17% of patients requiring therapeutic laparotomy. 2
• FAST has particularly poor sensitivity (56-71%) for detecting solid organ injuries compared to its high specificity (97-100%). 1
• FAST should never be used as the sole diagnostic test in patients with abdominal tenderness—a negative FAST does not exclude significant injury. 2
• FAST is most useful for rapid triage in unstable patients to detect free fluid, not for definitive diagnosis in stable patients. 1

Management Algorithm Based on Findings

If CT Shows Significant Free Fluid or Solid Organ Injury

• Hemodynamically stable patients with solid organ injuries (spleen, liver, kidney) can be managed non-operatively with serial examinations and monitoring. 1
• Hemodynamically unstable patients with free fluid require urgent surgical exploration. 1
• Free intraperitoneal fluid without solid organ injury warrants careful evaluation for bowel or mesenteric injury (present in 7-8% of cases). 6

If CT is Negative

• Patients with negative CT scans have a 99.63% negative predictive value for requiring surgical intervention and do not require hospital admission for observation. 6
• The false-negative rate is extremely low—only 9 of 1,809 patients (0.5%) with negative CT required subsequent laparotomy. 6
• Discharge from the emergency department is safe after negative CT in stable patients without distracting injuries or altered mental status. 6

Common Pitfalls to Avoid

• Do not rely on "mild" tenderness to guide decisions—the severity of tenderness does not correlate with injury severity, and 43% of patients with blunt abdominal trauma present with no specific complaints. 7
• Do not use diagnostic peritoneal lavage—it is outdated, invasive, and cannot identify specific organ injuries or retroperitoneal trauma. 2
• Do not repeat FAST examinations in patients with peritoneal signs instead of proceeding to CT—this delays definitive diagnosis. 2
• Do not discharge patients without imaging based on reassuring examination alone—occult injuries requiring splenectomy have been documented in patients without pain or tenderness. 3
• Do not order plain radiographs as the primary diagnostic modality—they have limited diagnostic value and rarely change management. 4

Special Considerations

Observation Period for Equivocal Cases

• If CT cannot be performed immediately and clinical suspicion is moderate, a 4-8 hour observation period with serial physical examinations may be appropriate. 6
• However, this should not replace definitive imaging in patients with any concerning features. 3, 7

Associated Injuries

• Maintain high suspicion for pelvic fractures (25% incidence in multiple trauma), which are associated with massive hemorrhage and concomitant abdominal injuries. 1
• Head injuries greatly increase mortality risk and may mask abdominal findings. 7