Final answer:
When a nurse finds that a postpartum client has saturated a perineal pad within 15 minutes, immediate notification of the healthcare provider is crucial as it may indicate postpartum hemorrhage, a serious condition.
Step-by-step explanation:
On examining a client who gave birth 3 hours ago and finds that the client has completely saturated a perineal pad within 15 minutes, the nurse should take the following action: notify the healthcare provider immediately. This could be a sign of postpartum hemorrhage, which is a potentially life-threatening condition requiring urgent medical attention. While assessing vital signs and massaging the uterus are also important in cases of heavy bleeding, these actions should be undertaken in conjunction with notifying the healthcare provider for immediate intervention.