A 72-year-old woman falls at home after an episode of dizziness. She had been complaining of low-back pain for 3 days before the fall. In the emergency department, she is hypotensive and has cold, clammy extremities. A pulsating mass is palpable on abdominal examination. Following resuscitation, the next step in the management should involve which of the following?
Peritoneal lavage Immediate abdominal exploration CT scan of the abdomen Abdominal aortogram