Why does a man need wife to sign for him to get vasectomy but she can get hysterectomy without him signing?

I've never heard of this before. I would have to say that it's your body, and you shouldn't have to have anybody's permission to get something done to it. I worked in a Surgery Center for 2 years and never came across this. In fact medically speaking you don't have to tell you partner anything, they don't even have rights to know what you are having done.