Transient Improvement in Surgery — 40yo Woman | Trauma Surgery | SMLE Q#919

A 40-year-old woman is brought to the emergency department after a high-speed motor vehicle collision. She is pale and diaphoretic. She received 1 L IV crystalloid and type O negative packed red blood cells with transient improvement, then recurrent hypotension. She has right upper quadrant tenderness and abdominal distension without external bleeding. Portable chest radiograph shows a widened mediastinum. Focused Assessment with Sonography for Trauma (FAST) shows free intraperitoneal fluid. She remains hypotensive despite ongoing resuscitation and is a transient responder. What is the most appropriate next step in management?