Is it obligatory for the surgeon to renew his intention with God for each patient he performs surgery on, or is the initial intention at the start of work sufficient?

The intention you made at the beginning of your work benefits you, and you will be rewarded for it. However, it is indispensable to renew it before each surgical operation, because deeds are only rewarded if their doer intends them as a means of drawing closer to Allah, based on the Prophet’s (peace be upon him) saying: “Deeds are but by intentions, and every person shall have but what he intended.” And also: “There is no reward except for the sake of Allah, and no deed except with an intention.” The valid intention must accompany the act. If it pertains to a future matter, it is merely a resolve. The intention must accompany the beginning of the act of worship. Forming and renewing the intention is not difficult, as intention follows knowledge and will. Intention is the act of linking one’s aim to a specific objective; it is the purpose behind the action.