When one sky-dives, races cars, or has consensual sex, death is a possible consequence and acceptance of that is implicit in choosing to engage in that activity. I cannot, in good conscience, compel someone to run that risk who did not, or legally could not, make that choice of their free will.
So you're going to guarantee the death of one innocent human, to avoid the slight risk of death to the other innocent human? Even though, if nature is allowed to take its course, both patients will probably end up in good health? I've already been through this with CAnnoneer, and he's since come around closer to my point of view. You will be assimilated.*
And abortions are not without risk of death, either.
For example, suppose someone has total kidney failure, and suppose I'm a potential donor - the ONLY potential donor. SHould I be compelled to donate?
Hey, you got your apple on my orange! This false comparison could be aborted in at least a couple of different ways. For one thing, the rape victim has already been compelled. It's not so much a question of compulsion, as a question of when killing is justified.
A closer analogy would be the old classic,
The Case of the Famous Violinist, in which a person awakens to find themselves in a hospital bed, with another person attached to them with tubes, and dependent on them for kidney function. In this case, the violation has already occurred, and the only item in question is the obligation to continue to nourish another person.
But that old chestnut is very flawed. A pregnant woman is not usually confined to a hospital bed, with tubes sticking out everywhere. And even if the mother was raped; the resulting pregnancy, though unwanted, is still a natural condition, for which the body was designed, not a hospital procedure. And an embryo or fetus is not a sick person. No matter how healthy she is, dependence on her mother's body is her normal and natural state for that nine months. And the kidnapped dialysis provider will not go through the psychological complications that many women feel when they abort their children.
And so on and so forth. The Violinist argument has been around longer than I have, so I'm sure you could find plenty of discussions about it on the web.
*I'm not taking credit for CAnnoneer's "major personal turn." Especially since I don't know whether he still feels that way.