Final answer:
A drop in blood pressure to 77/50 mmHg warrants immediate intervention by the nurse.
Step-by-step explanation:
In this case, the assessment finding that warrants immediate intervention by the nurse is a drop in blood pressure to 77/50 mmHg. This indicates that the client is experiencing hypotension, which could be a result of bleeding or inadequate fluid resuscitation. Immediate intervention is necessary to stabilize the client's blood pressure and prevent further complications.