Final answer:
During the first 12 hours after delivery, the nurse should apply cold compresses to a postpartum client with a small vulvar hematoma.
Step-by-step explanation:
The nurse developing a plan of care for a postpartum client with a small vulvar hematoma should include the specific action of applying cold compresses during the first 12 hours after delivery. Cold compresses help to reduce swelling and provide pain relief by causing vasoconstriction, which can reduce the size of the hematoma and limit bleeding. It is essential to monitor the hematoma for signs of growth or increased pain, which would warrant further medical evaluation. Other measures can include pain management, often with non-steroidal anti-inflammatory drugs (NSAIDs), once cleared by a physician, and monitoring for any signs of infection or complications.