Final answer:
The most appropriate next step in management for a patient with a stab wound, instability, rebound tenderness, rigidity, or evisceration is to prepare for immediate surgical exploration.
Step-by-step explanation:
The most appropriate next step in management for a patient with a stab wound, instability, rebound tenderness, rigidity, or evisceration is to prepare for immediate surgical exploration. These symptoms indicate a potentially serious intra-abdominal injury that requires urgent surgical intervention to assess and repair the damage. Other steps such as performing a FAST exam, administering fluids and blood products, or obtaining a CT scan may be part of the management plan, but immediate surgical exploration is the most crucial step.