Medical tests are rarely a pleasant experience, especially if you're worried that something could be seriously wrong. That's true even though we know that regular screenings and tests often help doctors catch issues early.
But of course, humans don't always behave rationally. Sometimes people will go to great lengths to avoid hearing bad news. Social scientists call this sort of behavior information aversion, or the ostrich effect (based on the old myth that ostriches bury their heads in the sand when they're scared).