My fantasies about medical situations always toe a fine line; If they are too unrealistic then they do nothing for me, but at the same time I know that anything actively sexual in a medical context is unrealistic. Talking about my (excessive) masturbation habit with a young, pretty, female doctor is as close to my fantasies as I ever could hope to get in real life. I use those experiences as a base for a lot of different fantasies though, I thought I'd share one:
My big fantasy about this doctor wasn't so much about her, as it was about her nurses. In reality, when I'd go for an appointment I'd check in, then take a seat in the waiting room and the nurse would come and get me. Before I saw the doctor I'd go with the nurse to an "exam room". I put it in quotes because it didn't have an exam table or much medical gear, and the door was almost always left open, but it did have a scale and a height ruler on the wall, and a blood pressure machine. There was a cabinet with some other stuff in it (some bottles, a thermometer), and a sofa and chair, and a laptop on a stand. The nurse would take my weight and blood pressure and ask how I was feeling and if anything had changed since my last visit. Then the doctor would come in and we'd proceed to her office.
In my fantasy version, everything is the same except that after I told the doctor about my masturbation habit and my difficulty orgasming during intercourse, she became concerned that I may have a more serious issue, or that I may be damaging myself by wanking so much. To monitor my condition more closely, she had the nurse change my pre-session exam. Now, instead of going to the abbreviated exam room, I'd be taken to a standard exam room and be given a full physical. Rather than keeping some of my clothes on, or wearing a gown, I'd be fully nude for the entire exam. Even before I was asked to, I'd begin to get an erection. After the basic physical was over the nurse would do a more detailed genital exam. For this part they'd need to bring another person in to make sure that nothing untoward was occurring. In my fantasies sometimes this would be one of the receptionists, sometimes it would be another nurse, sometimes it would be a male nurse. For the last part of the exam I'd be asked to masturbate myself to orgasm. In my mind I'm usually standing for this act, with both of them watching, sometimes with the nurse listening to my heartbeat with a stethoscope on my back. They would be making a video recording of me beating myself off too. The video would be attached to my electronic medical records for the doctor to review, but it would be there for the rest of my life as well. Every doctor I go to in the future would be able to view it. I'd ejaculate and they'd collect my semen, then I'd get dressed and the doctor would come for me, like in real life, we'd go to her office like in real life, but in the fantasy the first thing we do in the session is watch the video and discuss it.