What is the appropriate action if a patient's drain reservoir fills with bright red blood after previous emptying?

In the scenario where a patient's drain reservoir fills with bright red blood after it has been previously emptied, the most appropriate action is to call the surgeon back immediately. Bright red blood indicates fresh bleeding, which could suggest a serious complication such as active hemorrhage. This situation requires prompt evaluation and intervention by the surgical team to determine the source of the bleeding and address any potential issues that may endanger the patient's health.

Monitoring and managing bleeding is a critical aspect of post-operative care. The presence of bright red blood in the drain could indicate a need for emergency measures that a nurse or other healthcare provider may not be authorized to perform. Therefore, notifying the surgeon promptly allows for immediate assessment and appropriate surgical or medical interventions to ensure the patient's safety.

Taking actions such as increasing fluid intake, waiting for blood pressure stabilization, or changing the dressing on the drain may not adequately address the immediate risk of hemorrhage and could delay necessary surgical intervention, which is crucial in this circumstance.