Final answer:
The nurse should first encourage the client to drink 240 mL (8 oz) of water to promote voiding.
Step-by-step explanation:
The nurse should first encourage the client to drink 240 mL (8 oz) of water. This is because hydration can help stimulate urine production and promote voiding. In addition, drinking fluids can help flush out any residual anesthesia or medications that may be inhibiting the client's ability to void.