Medical phobia

When it comes to medical subjects, I imagine everything and I tend to pass out when it is to detailed (in a discussion or by images, video).
Therefore, I avoid any conversation on the matter or, when I’m watching a movie, I cover my eyes and ears in order.
When I have to do medical check up, I am so stressed that I tend to repel them, imaging the worse that could happen.
How could I deal with :
– my medical phobia ?
– my fear of the results ?
Thank you very much