Congrats on the offer! Most doctors I know in MBB tend to do well. Exit options (not going back to being a doctor) has never been a problem for those who left MBB.
I d be very pro-active about shaping (to the extent possible) your career at McK and beyond. Couple of thoughts around this. Bottom-line: Do Not Reinvent The Wheel!
(1) Ask McK colleagues: start talking to future McK colleagues NOW. You received the offer and should not hesitate to reach out to HR, ppl you already know from that office, or even LinkedIn to find ppl that you would like to talk to. HR will be likely happy to connect you to ppl you d like to speak to, same goes for practically anyone from your local office. They will most likely be willing to speak to you. Ask those individuals (perhaps some are former doctors, perhaps some purused interesting exit options after McK that you find interesting).
(2) MENTORING: I am not talking about those non-sense formal programs that all MBB firms are offering. I am talking about you finding someone and convincing someone to take you under his wing to become better at anything you do and someone you can talk through all major decisions. I always made sure that I had as many mentors (for different aspects) as possible. Mentors should be ppl you admire, perhaps ppl that demonstrate certain skills you love, mentors should be both some advanced juniors and senior partners / MDs. Different mentors for different purposes. Do not reinvent the wheel, leverage their experience.
(3) Headhunter: Most people treat headhunters like real estate agents, they only talk to them whenever they need them, mostly ad-hoc and mostly very transactional. Make it a habit to talk to headhunters perhaps once every 6 months in the beginning, at some point once a quarter. Just for a coffee or a lunch. Headhunters know each other, you will likely be on their minds if sth comes up. Also they ll use you by asking you if you d know someone for a specific opportunity in you local office. Once the time comes, you ll get a better and more friendly treatment by the typically otherwise more transactional headhunters.
Best,
Denis