Final answer:
Uterine atony is the condition that requires immediate nursing action because it can lead to significant postpartum hemorrhage if the uterus fails to contract properly after delivery.
Step-by-step explanation:
Among the findings listed for a client who delivered a healthy full-term baby girl 2 hours ago by cesarean section, the one that requires immediate nursing action is uterine atony. Uterine atony is a condition where the uterus fails to contract after the birth of the baby, which can lead to significant postpartum hemorrhage as the contracted uterus helps to compress the blood vessels that were attached to the placenta, thereby preventing excessive bleeding. In this scenario, while elevated blood pressure, bradycardia, and increased respiratory rate may also require monitoring and assessment, uterine atony is a critical issue that needs immediate attention to prevent severe blood loss and other associated complications. Therefore, the nurse must act promptly to massage the uterus and administer medications as prescribed to encourage uterine contractions and reduce the risk of hemorrhage.