Final answer:
The nurse should inform the client to increase fluid intake to flush out the barium after an upper gastrointestinal series with barium contrast.
Step-by-step explanation:
Following an upper gastrointestinal series with barium contrast, the nurse should provide the information to increase fluid intake to flush out the barium. Barium is a contrast agent used to coat the intestinal tract for better visualization during an X-ray. By increasing fluid intake, the client can help eliminate the barium from their system more efficiently.