What is the most diagnostic study for a adult male patient with no prior medical history, presenting with mild abdominal tenderness after a motorcycle accident, and stable vital signs?

Contrast-Enhanced CT Scan is the Most Diagnostic Study

For a hemodynamically stable adult male with mild abdominal tenderness after motorcycle accident, contrast-enhanced CT scan of the abdomen and pelvis is the definitive diagnostic study. 1, 2

Why CT is Superior to Other Options

CT is the Gold Standard

• Contrast-enhanced CT has sensitivity of 95-97% and specificity of 94-95% for detecting intra-abdominal injuries requiring intervention in blunt abdominal trauma. 3, 1
• CT with IV contrast is widely accepted as the primary modality and near-criterion standard for evaluating blunt abdominal trauma in hemodynamically stable patients. 3
• Modern 64-slice CT technology has further improved diagnostic accuracy, particularly for traditionally difficult-to-detect injuries such as pancreatic and bowel injuries. 3

Why FAST is Inadequate

• FAST has critical limitations: it requires 400-620 mL of free fluid to be detected reliably and is highly operator-dependent. 1
• FAST has a sensitivity of only 79% and misses injuries in 17% of patients requiring therapeutic laparotomy. 2
• A negative FAST exam does not exclude significant intra-abdominal injury and should not be relied upon as the sole diagnostic test in patients with abdominal tenderness. 2
• FAST cannot detect bowel injuries, mesenteric injuries, or diaphragmatic ruptures—all critical injuries that require operative intervention. 1, 4

Why Abdominal X-ray is Insufficient

• Plain radiography has extremely limited sensitivity for detecting intra-abdominal injuries in blunt trauma. 3
• X-ray cannot visualize solid organ injuries, mesenteric injuries, or most bowel perforations until late complications develop. 3

Why Retrograde Urography is Not Indicated

• Retrograde urography is a specialized study for evaluating urinary tract injuries, not a general screening tool for blunt abdominal trauma. 3
• It would only be considered if CT demonstrates specific urinary tract injury requiring further characterization.

Critical Clinical Context: Abdominal Tenderness Mandates CT

The presence of abdominal tenderness after blunt trauma mandates advanced imaging regardless of vital sign stability. 1

• Studies show that over one-third of "asymptomatic" patients had organ injuries, and 43% of blunt trauma patients with no specific complaints had significant injuries. 1
• Physical examination alone is unreliable in trauma patients, with 19% of patients with intra-abdominal injuries having no abdominal tenderness. 2
• The American College of Emergency Physicians Level C recommendation states that patients with isolated abdominal trauma and abdominal tenderness cannot be classified as low-risk and therefore require CT imaging. 3

Technical Specifications for CT

• IV contrast-only CT is sufficient; oral contrast is not necessary and does not improve detection of bowel injuries. 1, 5
• Single-phase IV contrast-enhanced examination is typically sufficient for comprehensive evaluation. 2
• CT provides comprehensive evaluation of all abdominal organs, including solid organs, bowel, mesentery, retroperitoneum, and diaphragm in a single examination. 2

Common Pitfalls to Avoid

• Do not rely on FAST as definitive imaging when abdominal tenderness is present—this is the most common error in trauma evaluation. 1, 2
• Do not delay CT imaging waiting for vital signs to deteriorate—hemodynamic stability does not exclude significant injury. 1
• Bowel injury remains one of the most commonly missed injuries, with 20% missed even on CT, making high-quality imaging essential. 1
• If CT findings are equivocal or non-specific, admission for observation with serial clinical examinations for 3-5 days is required, as delayed bowel perforation can occur hours later. 1