Final answer:
The assessment finding that requires immediate intervention is the bloody drainage from both ears, which suggests a basilar skull fracture.
Step-by-step explanation:
The assessment finding that warrants immediate intervention by the nurse in this case is the presence of bloody drainage from both ears (otorrhea).
Periorbital bruising and bloody drainage from the ears are both signs of a basilar skull fracture. A basilar skull fracture occurs when there is a fracture at the base of the skull, which can result in damage to important structures like the arteries supplying the brain.
Immediate intervention is necessary to prevent further complications and assess for any additional injuries or complications that may have occurred as a result of the motorcycle accident.