In the initial assessment of blunt abdominal trauma in a hemodynamically unstable patient, which diagnostic test is most appropriate to perform first?

• A. Diagnostic ultrasound
• B. Computed tomography of the abdomen and pelvis
• C. Diagnostic peritoneal lavage
• D. Flat and upright abdominal radiographs

Answer: (A)

In a hemodynamically unstable patient with blunt abdominal trauma, the priority is quickly identifying life-threatening intra-abdominal bleeding to decide urgent intervention. A bedside ultrasound test performed as a FAST exam provides rapid, noninvasive detection of free intraperitoneal fluid and can be done without moving the patient. If free fluid is found, it strongly indicates the need for emergent surgical exploration or rapid planning for definitive control of bleeding. In contrast, computed tomography offers excellent detail but requires stability and transport to the scanner, which isn’t feasible in an unstable patient. Diagnostic peritoneal lavage is more invasive and less favored as the first step, and plain abdominal radiographs lack sensitivity for intra-abdominal bleeding. So starting with a bedside FAST is the best initial diagnostic move in this scenario.