Final answer:
The nurse should instruct the client to discontinue warfarin 48 hours prior to the surgery due to its anticoagulant effect.
Step-by-step explanation:
The nurse should instruct the client to discontinue warfarin 48 hours prior to the surgery. Warfarin is an anticoagulant medication that increases the risk of bleeding during surgery. Discontinuing warfarin before surgery helps reduce the risk of excessive bleeding and complications during and after the procedure.