Diagnostic Evaluation for Blunt Abdominal Trauma

Clinical Considerations

The American College of Emergency Physicians recommends that 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 concerning peritoneal signs, with a sensitivity of only 79% and missing injuries in 17% of patients requiring therapeutic laparotomy 3
Physical examination findings of rebound tenderness and guarding indicate peritoneal irritation, which mandates definitive imaging regardless of FAST results, as physical examination is unreliable in trauma patients, with 19% of patients with intra-abdominal injuries having no abdominal tenderness 5, 2

CT has superior sensitivity (97%) and specificity (95%) for detecting intra-abdominal injuries requiring intervention in blunt abdominal trauma, particularly critical for detecting bowel injuries, which FAST frequently misses, with a sensitivity for small bowel perforation by CT of 92-94% 1, 4
The use of IV contrast-enhanced CT of the abdomen and pelvis is recommended, as it increases detection of solid organ injuries, vascular injuries, and active bleeding, with single-phase IV contrast-enhanced examination typically sufficient 5, 2

Repeating the FAST exam is inappropriate in patients with peritoneal signs, as fluid takes time to accumulate, and serial FAST may be helpful in some scenarios, but not when peritoneal signs are already present 3
Diagnostic peritoneal lavage is outdated, as it is invasive and cannot identify specific organ injuries or retroperitoneal trauma, with CT providing comprehensive evaluation of all abdominal organs in a single examination 1, 4, 5