Final answer:
The nurse should alert the surgeon about the patient's abnormal vital signs indicating a potential infection and hemodynamic instability, which can contraindicate surgery and might require immediate medical intervention.
Step-by-step explanation:
The nurse must immediately notify the surgeon of the patient's vital signs because they suggest the presence of an infection and potential hemodynamic instability. The elevated temperature of 39° C (102° F) indicates the possibility of an infection, which is a risk factor for sepsis and a contraindication for surgery. The decreased blood pressure (BP of 84/50), elevated heart rate of 120 bpm, and elevated white blood cell (WBC) count further support the potential diagnosis of an infection or sepsis. These signs are alarming, especially in the preoperative setting, as they may indicate a systemic response that could lead to shock or other serious complications if not treated promptly.